Gary Tsai, MD

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.

Overview

Chamomile, a member of the Asteraceae/Compositae family, is one of the oldest herbal medicines. It has been used for hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations have been developed, the most popular being herbal tea.²⁴

A controlled clinical trial of chamomile extract suggested that it may have modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Individuals with a hypersensitivity to plants of the Asteraceae (Compositae) family such as ragweed (Ambrosia spp.), marigold flower (Calendula officinalis), and chrysanthemum (Chrysanthemum spp.) may show a similar reaction to chamomile.²⁵

Anxiety. A controlled clinical trial of chamomile extract for generalized anxiety disorder (GAD) suggested that it may have modest anxiolytic activity in patients with mild to moderate GAD.²⁶ Another randomized, double-blind, placebo-controlled trial found oral chamomile extract was efficacious and well-tolerated in patients experiencing mild to moderate GAD and may provide an alternative therapeutic anxiolytic for patients with mild GAD.²⁵ In addition to its anxiolytic activity, chamomile may also provide clinically meaningful antidepressant activity.²⁶

Insomnia. Chamomile may have some impact on sleep diary measures (total sleep time, sleep efficiency, sleep latency, wake after sleep onset, sleep quality, and number of awakenings) relative to placebo in adults with chronic primary insomnia, according to a small randomized, double-blind, placebo-controlled pilot trial involving 34 patients.²⁷ However, a systematic review found no statistically significant difference between any herbal medicine (including chamomile) and placebo, for clinical efficacy in patients with insomnia. A similar, or smaller, number of adverse events per person were reported with chamomile compared with placebo, suggesting safe use.²⁸

Infantile colic. A small prospective double-blind study on the use of chamomile-containing tea on infantile colic showed statistically significant symptom improvement in tea-treated infants. The study did note, however, that prolonged ingestion of herbal teas may lead to decreased milk intake.^29,30

Adverse effects

As noted earlier, a systematic review found that the number of adverse events per person reported with chamomile was comparable to the number associated with placebo, suggesting that it is safe.²⁸

The bottom line

Chamomile appears to be safe with minimal adverse effects and may be effective for the treatment of anxiety, insomnia, and infantile colic.

Rosemary

Overview

Rosemary, officially known as Rosmarinus officinalis, is a medicinal evergreen plant native to the Mediterranean area that appears to increase microcapillary perfusion.³¹

Topical rosemary oil may be useful in the treatment of alopecia, with minimal adverse effects.

Alopecia. A randomized double-blind controlled trial found that essential oils including rosemary oil (as well as thyme, lavender, and cedarwood) massaged into the scalp improved hair growth in almost half of patients with alopecia areata after 7 months.³² Another randomized trial comparing rosemary oil to minoxidil 2% for androgenetic alopecia showed a significant increase in hair count at the 6-month endpoint compared with the baseline, but no significant difference was found between the study groups regarding hair count either at Month 3 or Month 6 (P >.05). ³¹

Adverse effects

In the randomized trial described above comparing rosemary oil to minoxidil 2%, adverse effects appeared to be rare for topical rosemary oil. Scalp itching was more frequent in the minoxidil group.³¹

The bottom line

Topical rosemary oil may be useful in the treatment of alopecia with minimal adverse effects.

Overview

Coffee is one of the most widely used botanicals with approximately 3.5 billion cups of coffee consumed per day worldwide. It is a popular beverage because of its unique aromatic taste and its use as a central nervous system stimulant. The coffee tree (genus coffea) is found throughout Latin America, Africa, and eastern Asia. Two of the most common commercially grown species are Coffea arabica (Arabicas) and Coffea canephora (Robusta). Processing and roasting methods may differ and produce variations in flavor and aroma. The degree of roasting also affects the caffeine content.

Coffee consumption leads to increased alertness and can boost mental performance. Based on the literature and US Food and Drug Administration recommendations, four 8-oz cups of coffee (about 400 mg of caffeine) daily is an acceptable average amount of caffeine. More than 500 mg/d is considered excessive use of coffee.^33,34

Overall mortality. A 2008 study showed that regular coffee was not associated with increased or decreased mortality in both men and women.³⁵ However, more recent studies show an inverse relationship between mortality and coffee consumption.

Specifically, a 2014 meta-analysis found an inverse relationship between coffee and mortality.³⁶ A large prospective cohort study from 2015 that included 79,234 women and 76,704 men found that drinking coffee was inversely associated with overall mortality.³⁷ In this cohort study, an inverse association were observed for deaths from heart disease, respiratory disease, diabetes, and self-harm.³⁷ While mechanisms were not analyzed, coffee may reduce mortality risk by affecting inflammation, lung function, insulin sensitivity, and depression.

Cardiovascular disease. Coffee consumption may modestly reduce the risk of stroke, according to a prospective cohort study of 83,076 women from the Nurses’ Health Study who were followed for 24 years.³⁸ Reduced cardiovascular mortality was also found in a large prospective cohort study, as noted in the mortality discussion above.³⁷ A 2014 meta-analysis concluded that coffee consumption is inversely associated with cardiovascular mortality. Drinking 3 or 4 cups a day appears to be the amount that may decrease one’s risk of death when compared to those who do not drink coffee at all.³⁶

Liver disease. Friedrich et al performed a study involving 379 patients with end stage liver disease, and found that coffee consumption delayed the progression of disease in patients with both alcoholic liver disease and primary sclerosing cholangitis.³⁹ Coffee consumption also increased long-term survival after liver transplantation.³⁹ However, the study found that coffee did not have any effect on patients with chronic viral hepatitis.

In a 2016 meta-analysis, caffeinated coffee consumption reduced hepatic fibrosis of nonalcoholic fatty liver disease, although caffeine consumption did not reduce the prevalence of nonalcoholic fatty liver disease.⁴⁰ Another meta-analysis, including 16 studies, also found caffeine reduced the risk for hepatic fibrosis and cirrhosis.⁴¹

Depression. Based on 2 different systematic reviews and meta-analyses from 2016, coffee consumption appears to have a significant protective effect, decreasing the risk of developing depression.^40,42

Alzheimer’s disease/dementia. Coffee, tea, and caffeine consumption show promise in reducing the risk of cognitive decline and dementia. Individuals who consume one to 2 cups of coffee per day had a decreased incidence of mild cognitive impairment compared to non-drinkers.⁴³ A 2015 Japanese study also found an inverse association between coffee consumption and dementia among women, nonsmokers, and those who do not drink alcohol.⁴⁴ Most recently, a 2016 study, the Women’s Health Initiative Memory Study, looked at incident dementia rates in women >65 years of age with high vs low caffeine intake. Women with higher caffeine intake were less likely to develop dementia or any cognitive impairment compared with those consuming <64 mg/day.⁴⁵

Type 2 diabetes. A 2009 prospective cohort study, which included 40,011 participants followed for more than 10 years, found that drinking at least 3 cups of coffee or tea was associated with a lowered risk of type 2 diabetes.⁴⁶ A 2009 systematic review of 20 cohort studies showed that high intakes of coffee, decaffeinated coffee, and tea are associated with a reduced risk of diabetes.⁴⁷

A meta-analysis of 12 studies involving 832,956 participants found an inverse relationship between cutaneous melanoma and coffee consumption.

Melanoma. A meta-analysis of 12 studies involving 832,956 participants demon­strated an inverse relationship between cutaneous melanoma and coffee consumption.⁴⁷ The risk of melanoma decreased by 3% and 4% for one cup/day of total coffee and caffeinated coffee consumption, respectively. Furthermore, a 2016 meta-analysis found that caffeinated coffee may have greater chemopreventive effects against melanoma than decaffeinated coffee.⁴⁸

Adverse effects

Despite the many potential benefits of coffee, caffeine is a potent drug that should be used with caution.⁴⁹ People with underlying heart problems should avoid caffeine due to concern that it may cause palpitations from tachycardia. It may worsen anxiety problems or depression. Coffee may increase the production of stomach acids, which can worsen acid reflux or stomach ulcers.

Regular coffee intake is associated with a lower risk of mortality, reduced CV events, and a reduction in liver disease progression.

Caffeine is a potent diuretic and may decrease absorption of calcium and cause OA. Caffeine may cause dependence and withdrawal symptoms. Some of the symptoms of withdrawal include drowsiness, headaches, irritability, nausea, and vomiting. It may disrupt sleeping patterns by causing jitters and sleeplessness.⁴⁹ Additionally, large amounts of caffeine may cause overdose and death.

The bottom line

Regular coffee intake is associated with a lower risk of mortality, reduced cardiovascular events, and a reduction in liver disease progression. Coffee may also have some utility for improving cognitive function and reducing the risk of type 2 diabetes. Caffeinated coffee should be limited to no more than 32 oz per day, due to the risk of insomnia, palpitations, anxiety, and gastritis.

Overview

Few natural products have been claimed to successfully treat as many disorders as chocolate. The modern concept of chocolate as food has overshadowed its traditional medicinal use, although recent trials have looked at evidence for some of its traditional uses. Chocolate is processed from the pod of the cacao plant. The earliest evidence for its medical use is in Mayan civilizations, and for most of its approximately 4000-year history, chocolate was consumed as a bitter drink referred to as the “drink of the Gods.” The traditional drink was mixed with water, vanilla, honey, chili peppers, and other spices. Important components in chocolate include flavonoids (antioxidants), cocoa butter, caffeine, theobromine, and phenylethylamine.  

Chocolate has stimulating, anti-inflammatory, neuroprotective, and cardioprotective effects, and improves the bioavailability of nitric oxide, which can improve blood pressure and platelet function.⁵⁰ Epicatechin (an antioxidant) in cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated by the anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-kappaB.⁵¹

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.

Dark chocolate appears to have the greatest benefit, as milk binds to antioxidants in chocolate, making them unavailable. Therefore, milk chocolate is not a good antioxidant source. There is no specific amount of chocolate that is known to be ideal, but an average of one to 2 ounces per day is often used in studies.

Cardiovascular effects. Chocolate does contain saturated fat, but a comparative, double-blind study found that short-term use of cocoa powder lowered plasma low-density lipoprotein (LDL) cholesterol, oxidized LDL, and apo B concentrations, and the plasma high-density lipoprotein (HDL) cholesterol concentration increased, relative to baseline in the low-, middle-, and high-cocoa groups.⁵² A small randomized crossover trial without clinical outcomes indicated that chocolate may increase HDL cholesterol without increasing weight.⁵³

A meta-analysis of short-term (2-12 weeks) treatment with dark chocolate/cocoa products showed reductions in LDL and total cholesterol, but no changes in HDL or triglycerides.⁵⁴ Another meta-analysis of RCTs, however, showed no short-term effect of cocoa/chocolate on lipid concentrations.⁵⁵ A randomized, placebo-controlled double-blind study of 62 patients with diabetes and hypertension showed that high polyphenol chocolate improved triglyceride levels.⁵⁶

Chocolate intake was associated with a lower risk of cognitive decline, with the greatest benefit noted in those who averaged more than one chocolate bar per week.

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.^57-59 A best case scenario analysis using a Markov model to predict the long-term effectiveness and cost effectiveness of daily dark chocolate consumption in a population with metabolic syndrome at high risk of cardiovascular disease concluded that daily consumption of dark chocolate can reduce cardiovascular events by 85 per 10,000 population treated over 10 years. The study concluded that $42 could be cost effectively spent per person per year on prevention strategies using dark chocolate.⁵⁹

In addition, a meta-analysis of 7 observational studies showed that high levels of chocolate consumption (any type) were associated with a 29% reduction in stroke compared with the lowest levels of chocolate intake.⁵⁷ Results of a similar meta-analysis from Neurology in 2012 also suggested that moderate chocolate consumption (any type) may lower the risk of stroke.⁶⁰

That said, 2 systematic reviews specifically relating to the risk of coronary heart disease and chocolate intake were inconclusive.^61-62

Blood pressure (BP). An RCT published in JAMA indicates that inclusion of small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced BP and improved the formation of vasodilative nitric oxide.⁶³ A meta-analysis of 10 RCTs also showed mean BP change in the active cocoa treatment arms across all trials was -4.5 mm Hg (95% confidence interval (CI), -5.9 to -3.2; P<.001) for systolic BP and -2.5 mm Hg (95% CI, -3.9 to -1.2; P<.001) for diastolic BP.⁶⁴

A Cochrane Review meta-analysis of 20 studies revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products compared with control in short-term trials of 2 to 18 weeks' duration.⁶⁵ Because studies have shown improvement in BP with chocolate intake, investigations into a role of chocolate in the prevention of preeclampsia have been undertaken. In some studies, chocolate intake was associated with reduced odds of preeclampsia and gestational hypertension.^66,67

Diabetes. Chocolate may exert significant vascular protection because of its antioxidant properties and possible increase of nitric oxide bioavailability, which can influence glucose uptake. A small trial comparing the effects of either dark or white chocolate bars (which do not contain the polyphenols) showed improved BP and glucose and insulin responses to an oral glucose tolerance test in healthy subjects on dark chocolate, but not white chocolate.⁶⁸ A comparison of chocolate consumption and risk of diabetes in the Physicians’ Health Study showed an inverse relationship between chocolate intake with incident disease, but this association appeared only to apply in younger and normal-body weight men after controlling for comprehensive lifestyles, including total energy consumption.⁶⁹

Fatigue. The effect of chocolate on a person’s energy level has been noted for centuries.⁷⁰ A small randomized trial showed improved energy levels in those treated with higher chocolate intakes. In a double-blind, randomized, clinical pilot crossover study, high cocoa liquor/polyphenol rich chocolate, reduced fatigue in subjects with chronic fatigue syndrome.⁷¹

Anxiety. A small randomized trial showed chocolate decreased anxiety in high-anxiety trait subjects and improved the anxiety level and the energy levels of low-anxiety trait participants.⁷²

Eye effects. The literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension. However, a meta-analysis showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension, and appear to play a part in both improving and slowing the progression of visual field loss.⁷³

Cognitive decline. Chocolate intake (any type) was associated with a lower risk of cognitive decline (RR = 0.59; 95% CI, 0.38-0.92) with the greatest benefit noted in those who averaged more than one chocolate bar or one tablespoon of cocoa powder per week. This protective effect was observed only among subjects with an average daily consumption of caffeine <75  mg (69% of the participants; RR = 0.50; 95% CI, 0.31-0.82).⁷⁴

The bottom line

Chocolate with high cocoa content (dark chocolate) appears to be safe and beneficial as part of a healthy diet and lifestyle that includes exercise and stress reduction to decrease cardiovascular risk and may improve energy levels.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.

Overview

Chamomile, a member of the Asteraceae/Compositae family, is one of the oldest herbal medicines. It has been used for hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations have been developed, the most popular being herbal tea.²⁴

A controlled clinical trial of chamomile extract suggested that it may have modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Individuals with a hypersensitivity to plants of the Asteraceae (Compositae) family such as ragweed (Ambrosia spp.), marigold flower (Calendula officinalis), and chrysanthemum (Chrysanthemum spp.) may show a similar reaction to chamomile.²⁵

Anxiety. A controlled clinical trial of chamomile extract for generalized anxiety disorder (GAD) suggested that it may have modest anxiolytic activity in patients with mild to moderate GAD.²⁶ Another randomized, double-blind, placebo-controlled trial found oral chamomile extract was efficacious and well-tolerated in patients experiencing mild to moderate GAD and may provide an alternative therapeutic anxiolytic for patients with mild GAD.²⁵ In addition to its anxiolytic activity, chamomile may also provide clinically meaningful antidepressant activity.²⁶

Insomnia. Chamomile may have some impact on sleep diary measures (total sleep time, sleep efficiency, sleep latency, wake after sleep onset, sleep quality, and number of awakenings) relative to placebo in adults with chronic primary insomnia, according to a small randomized, double-blind, placebo-controlled pilot trial involving 34 patients.²⁷ However, a systematic review found no statistically significant difference between any herbal medicine (including chamomile) and placebo, for clinical efficacy in patients with insomnia. A similar, or smaller, number of adverse events per person were reported with chamomile compared with placebo, suggesting safe use.²⁸

Infantile colic. A small prospective double-blind study on the use of chamomile-containing tea on infantile colic showed statistically significant symptom improvement in tea-treated infants. The study did note, however, that prolonged ingestion of herbal teas may lead to decreased milk intake.^29,30

Adverse effects

As noted earlier, a systematic review found that the number of adverse events per person reported with chamomile was comparable to the number associated with placebo, suggesting that it is safe.²⁸

The bottom line

Chamomile appears to be safe with minimal adverse effects and may be effective for the treatment of anxiety, insomnia, and infantile colic.

Rosemary

Overview

Rosemary, officially known as Rosmarinus officinalis, is a medicinal evergreen plant native to the Mediterranean area that appears to increase microcapillary perfusion.³¹

Topical rosemary oil may be useful in the treatment of alopecia, with minimal adverse effects.

Alopecia. A randomized double-blind controlled trial found that essential oils including rosemary oil (as well as thyme, lavender, and cedarwood) massaged into the scalp improved hair growth in almost half of patients with alopecia areata after 7 months.³² Another randomized trial comparing rosemary oil to minoxidil 2% for androgenetic alopecia showed a significant increase in hair count at the 6-month endpoint compared with the baseline, but no significant difference was found between the study groups regarding hair count either at Month 3 or Month 6 (P >.05). ³¹

Adverse effects

In the randomized trial described above comparing rosemary oil to minoxidil 2%, adverse effects appeared to be rare for topical rosemary oil. Scalp itching was more frequent in the minoxidil group.³¹

The bottom line

Topical rosemary oil may be useful in the treatment of alopecia with minimal adverse effects.

Overview

Coffee is one of the most widely used botanicals with approximately 3.5 billion cups of coffee consumed per day worldwide. It is a popular beverage because of its unique aromatic taste and its use as a central nervous system stimulant. The coffee tree (genus coffea) is found throughout Latin America, Africa, and eastern Asia. Two of the most common commercially grown species are Coffea arabica (Arabicas) and Coffea canephora (Robusta). Processing and roasting methods may differ and produce variations in flavor and aroma. The degree of roasting also affects the caffeine content.

Coffee consumption leads to increased alertness and can boost mental performance. Based on the literature and US Food and Drug Administration recommendations, four 8-oz cups of coffee (about 400 mg of caffeine) daily is an acceptable average amount of caffeine. More than 500 mg/d is considered excessive use of coffee.^33,34

Overall mortality. A 2008 study showed that regular coffee was not associated with increased or decreased mortality in both men and women.³⁵ However, more recent studies show an inverse relationship between mortality and coffee consumption.

Specifically, a 2014 meta-analysis found an inverse relationship between coffee and mortality.³⁶ A large prospective cohort study from 2015 that included 79,234 women and 76,704 men found that drinking coffee was inversely associated with overall mortality.³⁷ In this cohort study, an inverse association were observed for deaths from heart disease, respiratory disease, diabetes, and self-harm.³⁷ While mechanisms were not analyzed, coffee may reduce mortality risk by affecting inflammation, lung function, insulin sensitivity, and depression.

Cardiovascular disease. Coffee consumption may modestly reduce the risk of stroke, according to a prospective cohort study of 83,076 women from the Nurses’ Health Study who were followed for 24 years.³⁸ Reduced cardiovascular mortality was also found in a large prospective cohort study, as noted in the mortality discussion above.³⁷ A 2014 meta-analysis concluded that coffee consumption is inversely associated with cardiovascular mortality. Drinking 3 or 4 cups a day appears to be the amount that may decrease one’s risk of death when compared to those who do not drink coffee at all.³⁶

Liver disease. Friedrich et al performed a study involving 379 patients with end stage liver disease, and found that coffee consumption delayed the progression of disease in patients with both alcoholic liver disease and primary sclerosing cholangitis.³⁹ Coffee consumption also increased long-term survival after liver transplantation.³⁹ However, the study found that coffee did not have any effect on patients with chronic viral hepatitis.

In a 2016 meta-analysis, caffeinated coffee consumption reduced hepatic fibrosis of nonalcoholic fatty liver disease, although caffeine consumption did not reduce the prevalence of nonalcoholic fatty liver disease.⁴⁰ Another meta-analysis, including 16 studies, also found caffeine reduced the risk for hepatic fibrosis and cirrhosis.⁴¹

Depression. Based on 2 different systematic reviews and meta-analyses from 2016, coffee consumption appears to have a significant protective effect, decreasing the risk of developing depression.^40,42

Alzheimer’s disease/dementia. Coffee, tea, and caffeine consumption show promise in reducing the risk of cognitive decline and dementia. Individuals who consume one to 2 cups of coffee per day had a decreased incidence of mild cognitive impairment compared to non-drinkers.⁴³ A 2015 Japanese study also found an inverse association between coffee consumption and dementia among women, nonsmokers, and those who do not drink alcohol.⁴⁴ Most recently, a 2016 study, the Women’s Health Initiative Memory Study, looked at incident dementia rates in women >65 years of age with high vs low caffeine intake. Women with higher caffeine intake were less likely to develop dementia or any cognitive impairment compared with those consuming <64 mg/day.⁴⁵

Type 2 diabetes. A 2009 prospective cohort study, which included 40,011 participants followed for more than 10 years, found that drinking at least 3 cups of coffee or tea was associated with a lowered risk of type 2 diabetes.⁴⁶ A 2009 systematic review of 20 cohort studies showed that high intakes of coffee, decaffeinated coffee, and tea are associated with a reduced risk of diabetes.⁴⁷

A meta-analysis of 12 studies involving 832,956 participants found an inverse relationship between cutaneous melanoma and coffee consumption.

Melanoma. A meta-analysis of 12 studies involving 832,956 participants demon­strated an inverse relationship between cutaneous melanoma and coffee consumption.⁴⁷ The risk of melanoma decreased by 3% and 4% for one cup/day of total coffee and caffeinated coffee consumption, respectively. Furthermore, a 2016 meta-analysis found that caffeinated coffee may have greater chemopreventive effects against melanoma than decaffeinated coffee.⁴⁸

Adverse effects

Despite the many potential benefits of coffee, caffeine is a potent drug that should be used with caution.⁴⁹ People with underlying heart problems should avoid caffeine due to concern that it may cause palpitations from tachycardia. It may worsen anxiety problems or depression. Coffee may increase the production of stomach acids, which can worsen acid reflux or stomach ulcers.

Regular coffee intake is associated with a lower risk of mortality, reduced CV events, and a reduction in liver disease progression.

Caffeine is a potent diuretic and may decrease absorption of calcium and cause OA. Caffeine may cause dependence and withdrawal symptoms. Some of the symptoms of withdrawal include drowsiness, headaches, irritability, nausea, and vomiting. It may disrupt sleeping patterns by causing jitters and sleeplessness.⁴⁹ Additionally, large amounts of caffeine may cause overdose and death.

The bottom line

Regular coffee intake is associated with a lower risk of mortality, reduced cardiovascular events, and a reduction in liver disease progression. Coffee may also have some utility for improving cognitive function and reducing the risk of type 2 diabetes. Caffeinated coffee should be limited to no more than 32 oz per day, due to the risk of insomnia, palpitations, anxiety, and gastritis.

Overview

Few natural products have been claimed to successfully treat as many disorders as chocolate. The modern concept of chocolate as food has overshadowed its traditional medicinal use, although recent trials have looked at evidence for some of its traditional uses. Chocolate is processed from the pod of the cacao plant. The earliest evidence for its medical use is in Mayan civilizations, and for most of its approximately 4000-year history, chocolate was consumed as a bitter drink referred to as the “drink of the Gods.” The traditional drink was mixed with water, vanilla, honey, chili peppers, and other spices. Important components in chocolate include flavonoids (antioxidants), cocoa butter, caffeine, theobromine, and phenylethylamine.  

Chocolate has stimulating, anti-inflammatory, neuroprotective, and cardioprotective effects, and improves the bioavailability of nitric oxide, which can improve blood pressure and platelet function.⁵⁰ Epicatechin (an antioxidant) in cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated by the anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-kappaB.⁵¹

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.

Dark chocolate appears to have the greatest benefit, as milk binds to antioxidants in chocolate, making them unavailable. Therefore, milk chocolate is not a good antioxidant source. There is no specific amount of chocolate that is known to be ideal, but an average of one to 2 ounces per day is often used in studies.

Cardiovascular effects. Chocolate does contain saturated fat, but a comparative, double-blind study found that short-term use of cocoa powder lowered plasma low-density lipoprotein (LDL) cholesterol, oxidized LDL, and apo B concentrations, and the plasma high-density lipoprotein (HDL) cholesterol concentration increased, relative to baseline in the low-, middle-, and high-cocoa groups.⁵² A small randomized crossover trial without clinical outcomes indicated that chocolate may increase HDL cholesterol without increasing weight.⁵³

A meta-analysis of short-term (2-12 weeks) treatment with dark chocolate/cocoa products showed reductions in LDL and total cholesterol, but no changes in HDL or triglycerides.⁵⁴ Another meta-analysis of RCTs, however, showed no short-term effect of cocoa/chocolate on lipid concentrations.⁵⁵ A randomized, placebo-controlled double-blind study of 62 patients with diabetes and hypertension showed that high polyphenol chocolate improved triglyceride levels.⁵⁶

Chocolate intake was associated with a lower risk of cognitive decline, with the greatest benefit noted in those who averaged more than one chocolate bar per week.

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.^57-59 A best case scenario analysis using a Markov model to predict the long-term effectiveness and cost effectiveness of daily dark chocolate consumption in a population with metabolic syndrome at high risk of cardiovascular disease concluded that daily consumption of dark chocolate can reduce cardiovascular events by 85 per 10,000 population treated over 10 years. The study concluded that $42 could be cost effectively spent per person per year on prevention strategies using dark chocolate.⁵⁹

In addition, a meta-analysis of 7 observational studies showed that high levels of chocolate consumption (any type) were associated with a 29% reduction in stroke compared with the lowest levels of chocolate intake.⁵⁷ Results of a similar meta-analysis from Neurology in 2012 also suggested that moderate chocolate consumption (any type) may lower the risk of stroke.⁶⁰

That said, 2 systematic reviews specifically relating to the risk of coronary heart disease and chocolate intake were inconclusive.^61-62

Blood pressure (BP). An RCT published in JAMA indicates that inclusion of small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced BP and improved the formation of vasodilative nitric oxide.⁶³ A meta-analysis of 10 RCTs also showed mean BP change in the active cocoa treatment arms across all trials was -4.5 mm Hg (95% confidence interval (CI), -5.9 to -3.2; P<.001) for systolic BP and -2.5 mm Hg (95% CI, -3.9 to -1.2; P<.001) for diastolic BP.⁶⁴

A Cochrane Review meta-analysis of 20 studies revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products compared with control in short-term trials of 2 to 18 weeks' duration.⁶⁵ Because studies have shown improvement in BP with chocolate intake, investigations into a role of chocolate in the prevention of preeclampsia have been undertaken. In some studies, chocolate intake was associated with reduced odds of preeclampsia and gestational hypertension.^66,67

Diabetes. Chocolate may exert significant vascular protection because of its antioxidant properties and possible increase of nitric oxide bioavailability, which can influence glucose uptake. A small trial comparing the effects of either dark or white chocolate bars (which do not contain the polyphenols) showed improved BP and glucose and insulin responses to an oral glucose tolerance test in healthy subjects on dark chocolate, but not white chocolate.⁶⁸ A comparison of chocolate consumption and risk of diabetes in the Physicians’ Health Study showed an inverse relationship between chocolate intake with incident disease, but this association appeared only to apply in younger and normal-body weight men after controlling for comprehensive lifestyles, including total energy consumption.⁶⁹

Fatigue. The effect of chocolate on a person’s energy level has been noted for centuries.⁷⁰ A small randomized trial showed improved energy levels in those treated with higher chocolate intakes. In a double-blind, randomized, clinical pilot crossover study, high cocoa liquor/polyphenol rich chocolate, reduced fatigue in subjects with chronic fatigue syndrome.⁷¹

Anxiety. A small randomized trial showed chocolate decreased anxiety in high-anxiety trait subjects and improved the anxiety level and the energy levels of low-anxiety trait participants.⁷²

Eye effects. The literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension. However, a meta-analysis showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension, and appear to play a part in both improving and slowing the progression of visual field loss.⁷³

Cognitive decline. Chocolate intake (any type) was associated with a lower risk of cognitive decline (RR = 0.59; 95% CI, 0.38-0.92) with the greatest benefit noted in those who averaged more than one chocolate bar or one tablespoon of cocoa powder per week. This protective effect was observed only among subjects with an average daily consumption of caffeine <75  mg (69% of the participants; RR = 0.50; 95% CI, 0.31-0.82).⁷⁴

The bottom line

Chocolate with high cocoa content (dark chocolate) appears to be safe and beneficial as part of a healthy diet and lifestyle that includes exercise and stress reduction to decrease cardiovascular risk and may improve energy levels.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.

Overview

Chamomile, a member of the Asteraceae/Compositae family, is one of the oldest herbal medicines. It has been used for hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations have been developed, the most popular being herbal tea.²⁴

A controlled clinical trial of chamomile extract suggested that it may have modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Individuals with a hypersensitivity to plants of the Asteraceae (Compositae) family such as ragweed (Ambrosia spp.), marigold flower (Calendula officinalis), and chrysanthemum (Chrysanthemum spp.) may show a similar reaction to chamomile.²⁵

Anxiety. A controlled clinical trial of chamomile extract for generalized anxiety disorder (GAD) suggested that it may have modest anxiolytic activity in patients with mild to moderate GAD.²⁶ Another randomized, double-blind, placebo-controlled trial found oral chamomile extract was efficacious and well-tolerated in patients experiencing mild to moderate GAD and may provide an alternative therapeutic anxiolytic for patients with mild GAD.²⁵ In addition to its anxiolytic activity, chamomile may also provide clinically meaningful antidepressant activity.²⁶

Insomnia. Chamomile may have some impact on sleep diary measures (total sleep time, sleep efficiency, sleep latency, wake after sleep onset, sleep quality, and number of awakenings) relative to placebo in adults with chronic primary insomnia, according to a small randomized, double-blind, placebo-controlled pilot trial involving 34 patients.²⁷ However, a systematic review found no statistically significant difference between any herbal medicine (including chamomile) and placebo, for clinical efficacy in patients with insomnia. A similar, or smaller, number of adverse events per person were reported with chamomile compared with placebo, suggesting safe use.²⁸

Infantile colic. A small prospective double-blind study on the use of chamomile-containing tea on infantile colic showed statistically significant symptom improvement in tea-treated infants. The study did note, however, that prolonged ingestion of herbal teas may lead to decreased milk intake.^29,30

Adverse effects

As noted earlier, a systematic review found that the number of adverse events per person reported with chamomile was comparable to the number associated with placebo, suggesting that it is safe.²⁸

The bottom line

Chamomile appears to be safe with minimal adverse effects and may be effective for the treatment of anxiety, insomnia, and infantile colic.

Rosemary

Overview

Rosemary, officially known as Rosmarinus officinalis, is a medicinal evergreen plant native to the Mediterranean area that appears to increase microcapillary perfusion.³¹

Topical rosemary oil may be useful in the treatment of alopecia, with minimal adverse effects.

Alopecia. A randomized double-blind controlled trial found that essential oils including rosemary oil (as well as thyme, lavender, and cedarwood) massaged into the scalp improved hair growth in almost half of patients with alopecia areata after 7 months.³² Another randomized trial comparing rosemary oil to minoxidil 2% for androgenetic alopecia showed a significant increase in hair count at the 6-month endpoint compared with the baseline, but no significant difference was found between the study groups regarding hair count either at Month 3 or Month 6 (P >.05). ³¹

Adverse effects

In the randomized trial described above comparing rosemary oil to minoxidil 2%, adverse effects appeared to be rare for topical rosemary oil. Scalp itching was more frequent in the minoxidil group.³¹

The bottom line

Topical rosemary oil may be useful in the treatment of alopecia with minimal adverse effects.

Overview

Coffee is one of the most widely used botanicals with approximately 3.5 billion cups of coffee consumed per day worldwide. It is a popular beverage because of its unique aromatic taste and its use as a central nervous system stimulant. The coffee tree (genus coffea) is found throughout Latin America, Africa, and eastern Asia. Two of the most common commercially grown species are Coffea arabica (Arabicas) and Coffea canephora (Robusta). Processing and roasting methods may differ and produce variations in flavor and aroma. The degree of roasting also affects the caffeine content.

Coffee consumption leads to increased alertness and can boost mental performance. Based on the literature and US Food and Drug Administration recommendations, four 8-oz cups of coffee (about 400 mg of caffeine) daily is an acceptable average amount of caffeine. More than 500 mg/d is considered excessive use of coffee.^33,34

Overall mortality. A 2008 study showed that regular coffee was not associated with increased or decreased mortality in both men and women.³⁵ However, more recent studies show an inverse relationship between mortality and coffee consumption.

Specifically, a 2014 meta-analysis found an inverse relationship between coffee and mortality.³⁶ A large prospective cohort study from 2015 that included 79,234 women and 76,704 men found that drinking coffee was inversely associated with overall mortality.³⁷ In this cohort study, an inverse association were observed for deaths from heart disease, respiratory disease, diabetes, and self-harm.³⁷ While mechanisms were not analyzed, coffee may reduce mortality risk by affecting inflammation, lung function, insulin sensitivity, and depression.

Cardiovascular disease. Coffee consumption may modestly reduce the risk of stroke, according to a prospective cohort study of 83,076 women from the Nurses’ Health Study who were followed for 24 years.³⁸ Reduced cardiovascular mortality was also found in a large prospective cohort study, as noted in the mortality discussion above.³⁷ A 2014 meta-analysis concluded that coffee consumption is inversely associated with cardiovascular mortality. Drinking 3 or 4 cups a day appears to be the amount that may decrease one’s risk of death when compared to those who do not drink coffee at all.³⁶

Liver disease. Friedrich et al performed a study involving 379 patients with end stage liver disease, and found that coffee consumption delayed the progression of disease in patients with both alcoholic liver disease and primary sclerosing cholangitis.³⁹ Coffee consumption also increased long-term survival after liver transplantation.³⁹ However, the study found that coffee did not have any effect on patients with chronic viral hepatitis.

In a 2016 meta-analysis, caffeinated coffee consumption reduced hepatic fibrosis of nonalcoholic fatty liver disease, although caffeine consumption did not reduce the prevalence of nonalcoholic fatty liver disease.⁴⁰ Another meta-analysis, including 16 studies, also found caffeine reduced the risk for hepatic fibrosis and cirrhosis.⁴¹

Depression. Based on 2 different systematic reviews and meta-analyses from 2016, coffee consumption appears to have a significant protective effect, decreasing the risk of developing depression.^40,42

Alzheimer’s disease/dementia. Coffee, tea, and caffeine consumption show promise in reducing the risk of cognitive decline and dementia. Individuals who consume one to 2 cups of coffee per day had a decreased incidence of mild cognitive impairment compared to non-drinkers.⁴³ A 2015 Japanese study also found an inverse association between coffee consumption and dementia among women, nonsmokers, and those who do not drink alcohol.⁴⁴ Most recently, a 2016 study, the Women’s Health Initiative Memory Study, looked at incident dementia rates in women >65 years of age with high vs low caffeine intake. Women with higher caffeine intake were less likely to develop dementia or any cognitive impairment compared with those consuming <64 mg/day.⁴⁵

Type 2 diabetes. A 2009 prospective cohort study, which included 40,011 participants followed for more than 10 years, found that drinking at least 3 cups of coffee or tea was associated with a lowered risk of type 2 diabetes.⁴⁶ A 2009 systematic review of 20 cohort studies showed that high intakes of coffee, decaffeinated coffee, and tea are associated with a reduced risk of diabetes.⁴⁷

A meta-analysis of 12 studies involving 832,956 participants found an inverse relationship between cutaneous melanoma and coffee consumption.

Melanoma. A meta-analysis of 12 studies involving 832,956 participants demon­strated an inverse relationship between cutaneous melanoma and coffee consumption.⁴⁷ The risk of melanoma decreased by 3% and 4% for one cup/day of total coffee and caffeinated coffee consumption, respectively. Furthermore, a 2016 meta-analysis found that caffeinated coffee may have greater chemopreventive effects against melanoma than decaffeinated coffee.⁴⁸

Adverse effects

Despite the many potential benefits of coffee, caffeine is a potent drug that should be used with caution.⁴⁹ People with underlying heart problems should avoid caffeine due to concern that it may cause palpitations from tachycardia. It may worsen anxiety problems or depression. Coffee may increase the production of stomach acids, which can worsen acid reflux or stomach ulcers.

Regular coffee intake is associated with a lower risk of mortality, reduced CV events, and a reduction in liver disease progression.

Caffeine is a potent diuretic and may decrease absorption of calcium and cause OA. Caffeine may cause dependence and withdrawal symptoms. Some of the symptoms of withdrawal include drowsiness, headaches, irritability, nausea, and vomiting. It may disrupt sleeping patterns by causing jitters and sleeplessness.⁴⁹ Additionally, large amounts of caffeine may cause overdose and death.

The bottom line

Regular coffee intake is associated with a lower risk of mortality, reduced cardiovascular events, and a reduction in liver disease progression. Coffee may also have some utility for improving cognitive function and reducing the risk of type 2 diabetes. Caffeinated coffee should be limited to no more than 32 oz per day, due to the risk of insomnia, palpitations, anxiety, and gastritis.

Overview

Few natural products have been claimed to successfully treat as many disorders as chocolate. The modern concept of chocolate as food has overshadowed its traditional medicinal use, although recent trials have looked at evidence for some of its traditional uses. Chocolate is processed from the pod of the cacao plant. The earliest evidence for its medical use is in Mayan civilizations, and for most of its approximately 4000-year history, chocolate was consumed as a bitter drink referred to as the “drink of the Gods.” The traditional drink was mixed with water, vanilla, honey, chili peppers, and other spices. Important components in chocolate include flavonoids (antioxidants), cocoa butter, caffeine, theobromine, and phenylethylamine.  

Chocolate has stimulating, anti-inflammatory, neuroprotective, and cardioprotective effects, and improves the bioavailability of nitric oxide, which can improve blood pressure and platelet function.⁵⁰ Epicatechin (an antioxidant) in cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated by the anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-kappaB.⁵¹

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.

Dark chocolate appears to have the greatest benefit, as milk binds to antioxidants in chocolate, making them unavailable. Therefore, milk chocolate is not a good antioxidant source. There is no specific amount of chocolate that is known to be ideal, but an average of one to 2 ounces per day is often used in studies.

Cardiovascular effects. Chocolate does contain saturated fat, but a comparative, double-blind study found that short-term use of cocoa powder lowered plasma low-density lipoprotein (LDL) cholesterol, oxidized LDL, and apo B concentrations, and the plasma high-density lipoprotein (HDL) cholesterol concentration increased, relative to baseline in the low-, middle-, and high-cocoa groups.⁵² A small randomized crossover trial without clinical outcomes indicated that chocolate may increase HDL cholesterol without increasing weight.⁵³

A meta-analysis of short-term (2-12 weeks) treatment with dark chocolate/cocoa products showed reductions in LDL and total cholesterol, but no changes in HDL or triglycerides.⁵⁴ Another meta-analysis of RCTs, however, showed no short-term effect of cocoa/chocolate on lipid concentrations.⁵⁵ A randomized, placebo-controlled double-blind study of 62 patients with diabetes and hypertension showed that high polyphenol chocolate improved triglyceride levels.⁵⁶

Chocolate intake was associated with a lower risk of cognitive decline, with the greatest benefit noted in those who averaged more than one chocolate bar per week.

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.^57-59 A best case scenario analysis using a Markov model to predict the long-term effectiveness and cost effectiveness of daily dark chocolate consumption in a population with metabolic syndrome at high risk of cardiovascular disease concluded that daily consumption of dark chocolate can reduce cardiovascular events by 85 per 10,000 population treated over 10 years. The study concluded that $42 could be cost effectively spent per person per year on prevention strategies using dark chocolate.⁵⁹

In addition, a meta-analysis of 7 observational studies showed that high levels of chocolate consumption (any type) were associated with a 29% reduction in stroke compared with the lowest levels of chocolate intake.⁵⁷ Results of a similar meta-analysis from Neurology in 2012 also suggested that moderate chocolate consumption (any type) may lower the risk of stroke.⁶⁰

That said, 2 systematic reviews specifically relating to the risk of coronary heart disease and chocolate intake were inconclusive.^61-62

Blood pressure (BP). An RCT published in JAMA indicates that inclusion of small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced BP and improved the formation of vasodilative nitric oxide.⁶³ A meta-analysis of 10 RCTs also showed mean BP change in the active cocoa treatment arms across all trials was -4.5 mm Hg (95% confidence interval (CI), -5.9 to -3.2; P<.001) for systolic BP and -2.5 mm Hg (95% CI, -3.9 to -1.2; P<.001) for diastolic BP.⁶⁴

A Cochrane Review meta-analysis of 20 studies revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products compared with control in short-term trials of 2 to 18 weeks' duration.⁶⁵ Because studies have shown improvement in BP with chocolate intake, investigations into a role of chocolate in the prevention of preeclampsia have been undertaken. In some studies, chocolate intake was associated with reduced odds of preeclampsia and gestational hypertension.^66,67

Diabetes. Chocolate may exert significant vascular protection because of its antioxidant properties and possible increase of nitric oxide bioavailability, which can influence glucose uptake. A small trial comparing the effects of either dark or white chocolate bars (which do not contain the polyphenols) showed improved BP and glucose and insulin responses to an oral glucose tolerance test in healthy subjects on dark chocolate, but not white chocolate.⁶⁸ A comparison of chocolate consumption and risk of diabetes in the Physicians’ Health Study showed an inverse relationship between chocolate intake with incident disease, but this association appeared only to apply in younger and normal-body weight men after controlling for comprehensive lifestyles, including total energy consumption.⁶⁹

Fatigue. The effect of chocolate on a person’s energy level has been noted for centuries.⁷⁰ A small randomized trial showed improved energy levels in those treated with higher chocolate intakes. In a double-blind, randomized, clinical pilot crossover study, high cocoa liquor/polyphenol rich chocolate, reduced fatigue in subjects with chronic fatigue syndrome.⁷¹

Anxiety. A small randomized trial showed chocolate decreased anxiety in high-anxiety trait subjects and improved the anxiety level and the energy levels of low-anxiety trait participants.⁷²

Eye effects. The literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension. However, a meta-analysis showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension, and appear to play a part in both improving and slowing the progression of visual field loss.⁷³

Cognitive decline. Chocolate intake (any type) was associated with a lower risk of cognitive decline (RR = 0.59; 95% CI, 0.38-0.92) with the greatest benefit noted in those who averaged more than one chocolate bar or one tablespoon of cocoa powder per week. This protective effect was observed only among subjects with an average daily consumption of caffeine <75  mg (69% of the participants; RR = 0.50; 95% CI, 0.31-0.82).⁷⁴

The bottom line

Chocolate with high cocoa content (dark chocolate) appears to be safe and beneficial as part of a healthy diet and lifestyle that includes exercise and stress reduction to decrease cardiovascular risk and may improve energy levels.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

The National Center for Complementary and Integrative Health, a division of the National Institutes of Medicine, estimates that 38% of American adults use complementary and alternative medicine (including 17.7% who say they use “natural products”).¹ Despite the popularity of these products, many providers remain skeptical—and for good reason. Enthusiasts may offer dramatic anecdotes to “prove” their supplements’ worth, but little scientific support is available for most herbal remedies. There are, however, exceptions—capsaicin, butterbur, green tea, and peppermint—as this review of the medical literature reveals.

Worth noting as you consider this—or any—review of herbals is that while there is limited scientific evidence to establish the safety and efficacy of most herbal products, they are nonetheless freely sold without FDA approval because, under current regulations, they are considered dietary supplements. That legal designation means companies can manufacture, sell, and market herbs without first demonstrating safety and efficacy, as is required for pharmaceutical drugs. Because herbal medications do not require the same testing through the large randomized controlled trials (RCTs) required for pharmaceuticals, evidence is often based on smaller RCTs and other studies of lower overall quality. Despite these limitations, we believe it’s worth keeping an open mind about the value of evidence-based herbal and botanical treatments.

CAPSAICIN

Capsaicin, an active compound in chili peppers, provokes a burning sensation but also has a long history of use in pain treatment.² Qutenza, an FDA-approved, chemically synthesized 8% capsaicin patch, is identical to the naturally occurring molecule.² Topical capsaicin exerts its therapeutic effect by rapidly depleting substance P, thus reducing the transmission of pain from C fibers to higher neurologic centers in the area of administration.³

Meta-analyses and systematic reviews have shown capsaicin is effective for various painful conditions, including peripheral diabetic neuropathy, osteoarthritis (OA), low back pain (LBP), and postherpetic neuralgia (PHN).

Peripheral neuropathy. A Cochrane review of six randomized, double-blind, placebo-controlled studies of at least six weeks’ duration using topical 8% capsaicin to treat PHN and HIV-associated neuropathy concluded that high-concentration topical capsaicin provided more relief in patients with high pain levels than control patients who received a subtherapeutic (0.04%) capsaicin cream. Number-needed-to-treat values were between 8 and 12. Local adverse events were common, but not consistently reported enough to calculate a number needed to harm.⁴

OA. In randomized trials, capsaicin provided mild-to-moderate efficacy for patients with hand and knee OA, when compared with placebo.^5-7 A systematic review of capsaicin for all osteoarthritic conditions noted that there was consistent evidence that capsaicin gel was effective for OA.⁸ However, a 2013 Cochrane review of only knee OA noted that capsicum extract did not provide significant clinical improvement for pain or function and resulted in a significant number of adverse events.⁹

LBP. Based on a 2014 Cochrane review of three trials (755 subjects) of moderate quality, capsicum frutescens cream or plaster appeared more efficacious than placebo in people with chronic LBP.¹⁰ Based on current (low-quality) evidence in one trial, however, it’s not clear whether topical capsicum cream is more beneficial for acute LBP than placebo.¹⁰

PHN. Topical capsaicin is an FDA-approved treatment for PHN. A review and cost-effectiveness analysis demonstrated that 8% capsaicin had significantly higher effectiveness rates than the oral agents (tricyclic antidepressants, duloxetine, gabapentin, pregabalin) used to treat PHN.¹¹ The cost of the capsaicin patch was similar to a topical lidocaine patch and oral products for PHN.¹¹ A meta-analysis of seven RCTs indicated that 8% topical capsaicin was superior to the low-dose capsaicin patch for relieving pain associated with PHN.¹²

Continue to: Adverse effects

Very few toxic effects have been reported during a half-century of capsaicin use. Those that have been reported are mainly limited to mild local reactions.² The most common adverse effect of topical capsaicin is local irritation (burning, stinging, and erythema), which was reported in approximately 40% of patients.⁶ Nevertheless, more than 90% of the subjects in clinical studies were able to complete the studies, and pain rapidly resolved after patch removal.² Washing with soap and water may help prevent the compound from spreading to other parts of the body unintentionally.

The safety of the patch has been demonstrated with repeated dosing every three months for up to one year. However, the long-term risks of chronic capsaicin use and its effect on epidermal innervation are uncertain.⁵

The bottom line

Capsaicin appears to be an effective treatment for neuropathy and chronic LBP. It is FDA approved for the treatment of PHN. It may also benefit patients with OA and acute LBP. Serious adverse effects are uncommon with topical use. Common adverse effects include burning pain and irritation in the area of application, which can be intense and cause discontinuation.²

Continue to: BUTTERBUR

Petasites hybridus, also known as butterbur, is a member of the daisy family, Asteraceae, and is a perennial plant found throughout Europe and Asia.¹³ It was used as a remedy for ulcers, wounds, and inflammation in ancient Greece. Its calcium channel–blocking effects may counteract vasoconstriction and play a role in preventing hyperexcitation of neurons.¹⁴ Sesquiterpenes, the pharmacologically active compounds in butterbur, have strong anti-inflammatory and vasodilatory effects through lipoxygenase and leukotriene inhibition.¹⁴

Migraine headache. Butterbur appears to be effective in migraine prophylaxis. Several studies have shown butterbur to significantly reduce the number of migraine attacks per month when compared with placebo. In a small, randomized, placebo-controlled, parallel-group study on the efficacy and tolerability of a special butterbur root extract (Petadolex) for the prevention of migraine, response rate was 45% in the butterbur group vs 15% in the placebo group. Butterbur was well tolerated.¹⁵ Similar results were found in another RCT in which butterbur 75 mg bid significantly reduced migraine frequency by 48%, compared with 26% for the placebo group.¹⁶ Butterbur was well tolerated in this study, too, and no serious adverse events occurred. Findings suggest that 75 mg bid may be a good option for migraine prevention, given the agent’s safety profile.

Petadolex may also be a good option in pediatric migraine. A 2005 study in children and adolescents found that 77% of patients experienced a reduction in attacks by at least 50% with butterbur. Patients were treated with 50 mg to 150 mg over four months.¹⁷

In their 2012 guidelines for migraine prevention, the American Academy of Neurology (AAN) and American Headache Society gave butterbur a Level A recommendation, concluding that butterbur should be offered to patients with migraine to reduce the frequency and severity of migraine attacks.¹⁸ However, the AAN changed its position in 2015, redacting the recommendation due to serious safety concerns.¹⁹

Allergic rhinitis. Although the data are not convincing, some studies have shown that butterbur may be beneficial for the treatment of allergic rhinitis.^20,21

Continue to: Adverse effects

While the butterbur plant itself contains pyrrolizidine alkaloids (PA), which are hepatotoxic and carcinogenic, extracts of butterbur root that are almost completely free from these alkaloids are available. Patients who choose to use butterbur should be advised to use only products that are certified and labeled PA free.

Petadolex, the medication used in migraine studies, was initially approved by the German health regulatory authority, but approval was later withdrawn due to concerns about liver toxicity.²² In 2012, the United Kingdom’s Medicines and Health Care Products Regulatory Agency withdrew all butterbur products from the market due to associated cases of liver toxicity.²² Butterbur products are still available in the US market, and the risks and benefits should be discussed with all patients considering this treatment. Liver function monitoring is recommended for all patients using butterbur.²²

The herb can also cause dyspepsia, headache, itchy eyes, gastrointestinal symptoms, asthma, fatigue, and drowsiness. Additionally, people who are allergic to ragweed and daisies may have allergic reactions to butterbur. Eructation (belching) occurred in 7% of patients in a pediatric study.¹⁷

The bottom line

Butterbur appears to be efficacious for migraine prophylaxis, but long-term safety is unknown and serious concerns exist for liver toxicity.

Continue to: GREEN TEA

Most tea leaves come from the Camellia sinensis bush, but green and black tea are processed differently to produce different end products.²³ It is estimated that green tea accounts for approximately a quarter of all tea consumption and is most commonly consumed in Asian countries.²³ The health-promoting effects of green tea are mainly attributed to its polyphenol content.²⁴ Of the many types of tea, green tea has the highest concentration of polyphenols, including catechins, which are powerful antioxidants.^23,24 Green tea has been used in traditional Chinese and Indian medicine to control bleeding, improve digestion, and promote overall health.²³

Dementia. Green tea polyphenols may enhance cognition and may protect against the development of dementia. In-vitro studies have shown that green tea reduces hydrogen peroxide and ß-amyloid peptides, which are significant in the development of Alzheimer’s disease.²⁵ A 12-subject double-blind study found green tea increased working memory and had an impact on frontoparietal brain connections.²⁶ Furthermore, a cohort study with 13,645 Japanese participants over a five-year period found that frequent green tea consumption (> 5 cups per day) was associated with a lower risk for dementia.²⁷ Additional studies are needed, but green tea may be useful in the treatment or prevention of dementia in the future.

Coronary artery disease. In one study, green tea plasma and urinary concen­trations were associated with plasma biomarkers of cardiovascular disease and ­diabetes.²⁸ In one review, the consumption of green tea was associated with a statis­tically significant reduction in LDL cholesterol.²⁹ Furthermore, a 2015 systematic review and meta-analysis of prospective observational studies concluded that increased tea consumption (of any type) is associated with a reduced risk for coronary heart disease, cardiac death, stroke, and total mortality.³⁰

Cancer. Many studies have shown that green tea may reduce the risk for cancer, although epidemiologic evidence is inconsistent. Studies have shown that cancer rates tend to be lower in those who consume higher levels of green tea.^31,32 Whether this can be attributed solely to green tea remains debatable. Several other studies have shown that polyphenols in green tea can inhibit the growth of cancer cells, but the exact mechanism by which tea interacts with cancerous cells is unknown.²³

Several population-based studies have been performed, mostly in Japan, which showed green tea consumption reduced the risk for cancer. Fewer prostate cancer cases have been reported in men who consume green tea.³³ While studies have been performed to determine whether green tea has effects on pancreatic, esophageal, ovarian, breast, bladder, and colorectal cancer, the evidence remains inadequate.³²

Diabetes. Green tea has been shown in several studies to have a beneficial effect on diabetes. A retrospective Japanese cohort study showed that those who consumed green tea were one-third less likely to develop type 2 diabetes.³⁴ A 10-year study from Taiwan found lower body fat and smaller waist circumference in those who consumed green tea regularly.³⁵ A 2014 meta-analysis and systematic review of tea (any type) consumption and the risk for diabetes concluded that three or more cups of tea per day was associated with a lower risk for diabetes.³⁶ Another meta-analysis of 17 RCTs focused on green tea concluded that green tea improves glucose control and A1C values.³⁷

Continue to: Adverse effects

There have been concerns about potential hepatotoxicity induced by green tea intake.³⁸ However, a systematic review of 34 RCTs on liver-related adverse events from green tea showed only a slight elevation in liver function tests; no serious liver-related adverse events were reported.³⁸ This review suggested that liver-related adverse events after intake of green tea extracts are rare.³⁸

Consuming green tea in the diet may lower the risk for adverse effects since the concentration consumed is generally much lower than that found in extracts.

Contraindications to drinking green tea are few. Individuals with caffeine sensitivities could experience insomnia, anxiety, irritability, or upset stomach. Additionally, patients who are taking anticoagulation drugs, such as warfarin, should avoid green tea due to its vitamin K content, which can counter the effects of warfarin. Pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should use caution with green tea consumption.

The bottom line

Green tea consumption in the diet appears to be safe and may have beneficial effects on weight, dementia, and risk for diabetes, cancer, and cardiovascular disease. Patients may want to consider drinking green tea as part of a healthy diet, in combination with exercise.

Continue to: PEPPERMINT

Mentha piperita, also known as peppermint, is a hybrid between water mint and spearmint. It is found throughout Europe and North America and is commonly used in tea and toothpaste and as a flavoring for gum. Menthol and methyl salicylate are the main active ingredients in peppermint, and peppermint has calcium channel–blocker effects.³⁹ Menthol has been shown to help regulate cold and pain sensation through the TRPM8 receptor.⁴⁰ The peppermint herb is used both orally and topically, and has been studied in the treatment of multiple conditions.

Irritable bowel syndrome (IBS). It appears that peppermint inhibits spontaneous peristaltic activity, which reduces gastric emptying, decreases basal tone in the gastrointestinal tract, and slows down peristalsis in the gut.³⁹

The American College of Gastroenterology guidelines currently note that there is moderate-quality evidence for peppermint oil in the treatment of IBS.⁴¹ A Cochrane review concluded that peppermint appears to be beneficial for IBS-related symptoms and pain.⁴² In a systematic review of nine studies from 2014, peppermint oil was found to be more effective than placebo for IBS symptoms such as pain, bloating, gas, and diarrhea.⁴³ The review also indicated that peppermint oil is safe, with heartburn being the most common complaint.⁴³ A 2016 study also found that triple-coated microspheres containing peppermint oil reduced the frequency and intensity of IBS symptoms.⁴⁴

Non-ulcer dyspepsia. In combination with caraway oil, peppermint oil can be used to reduce symptoms of non-ulcer dyspepsia.^45,46 A multicenter, randomized, placebo-controlled, double-blind study found that 43.3% of subjects improved with a peppermint-caraway oil combination after eight weeks, compared with 3.5% receiving placebo.⁴⁶

Barium enema–related colonic spasm. Peppermint can relax the lower esophageal sphincter, and it has been shown to be useful as an antispasmodic agent for barium enema–related colonic spasm.^47,48

Itching/skin irritation. Peppermint, when applied topically, has been used to calm pruritus and relieve irritation and inflammation. It has a soothing and cooling effect on the skin. At least one study found it to be effective in the treatment of pruritus gravidarum, although the study population consisted of only 96 subjects.⁴⁹

Migraine headache. Initial small trials suggest that menthol is likely beneficial for migraine headaches. A pilot trial of 25 patients treated with topical menthol 6% gel for an acute migraine attack showed a significant improvement in headache intensity two hours after gel application.⁵⁰ In a randomized, triple-blind, placebo-controlled, crossover study of 35 patients, a menthol 10% solution was shown to be more efficacious as abortive treatment of migraine headaches than placebo.⁵¹

Tension headache. In a randomized, placebo-controlled, double-blind crossover study, topical peppermint oil showed a significant clinical reduction in tension headache pain.⁵² Another small, randomized, double-blind trial showed that tiger balm (containing menthol as the main ingredient) also produced statistically significant improvement in tension headache discomfort compared with placebo.⁵³

Continue to: Musculoskeletal pain

Musculoskeletal pain. A small study comparing topical menthol to ice for muscle soreness noted decreased perceived discomfort with menthol.⁵⁴ Menthol has also been shown to reduce pain in patients with knee OA.⁵⁵

Carpal tunnel syndrome (CTS). A triple-blind RCT concluded that topical menthol acutely reduced pain intensity in slaughterhouse workers with CTS, and it should be considered as an effective nonsystemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.⁵⁶

Adverse effects

Peppermint appears to be safe for most adults when used in small doses, and serious adverse effects are rare.^43,57 While peppermint tea appears to be safe in moderate-to-large amounts, people allergic to plants in the peppermint family (eg, mint, thyme, sage, rosemary, marjoram, basil, lavender) may experience allergic reactions with swelling, wheals, or erythema. Peppermint may also cause heartburn due to relaxation of the cardiac sphincter.

Other symptoms may include nausea, vomiting, flushing, and headache.⁵⁸ The herb may also be both hepatotoxic and nephrotoxic at extremely high doses.⁵⁹ Other considerations for women are that it can trigger menstruation and should be avoided during pregnancy. Due to uncertain efficacy in this population, peppermint oil should not be used on the face of infants, young children, or pregnant women.^58,59

The bottom line

Peppermint appears to be safe and well tolerated. It is useful in alleviating IBS symptoms and may be effective in the treatment of non-ulcerative dyspepsia, musculoskeletal pain, headache, and CTS.^54,55

The National Center for Complementary and Integrative Health, a division of the National Institutes of Medicine, estimates that 38% of American adults use complementary and alternative medicine (including 17.7% who say they use “natural products”).¹ Despite the popularity of these products, many providers remain skeptical—and for good reason. Enthusiasts may offer dramatic anecdotes to “prove” their supplements’ worth, but little scientific support is available for most herbal remedies. There are, however, exceptions—capsaicin, butterbur, green tea, and peppermint—as this review of the medical literature reveals.

Worth noting as you consider this—or any—review of herbals is that while there is limited scientific evidence to establish the safety and efficacy of most herbal products, they are nonetheless freely sold without FDA approval because, under current regulations, they are considered dietary supplements. That legal designation means companies can manufacture, sell, and market herbs without first demonstrating safety and efficacy, as is required for pharmaceutical drugs. Because herbal medications do not require the same testing through the large randomized controlled trials (RCTs) required for pharmaceuticals, evidence is often based on smaller RCTs and other studies of lower overall quality. Despite these limitations, we believe it’s worth keeping an open mind about the value of evidence-based herbal and botanical treatments.

CAPSAICIN

Capsaicin, an active compound in chili peppers, provokes a burning sensation but also has a long history of use in pain treatment.² Qutenza, an FDA-approved, chemically synthesized 8% capsaicin patch, is identical to the naturally occurring molecule.² Topical capsaicin exerts its therapeutic effect by rapidly depleting substance P, thus reducing the transmission of pain from C fibers to higher neurologic centers in the area of administration.³

Meta-analyses and systematic reviews have shown capsaicin is effective for various painful conditions, including peripheral diabetic neuropathy, osteoarthritis (OA), low back pain (LBP), and postherpetic neuralgia (PHN).

Peripheral neuropathy. A Cochrane review of six randomized, double-blind, placebo-controlled studies of at least six weeks’ duration using topical 8% capsaicin to treat PHN and HIV-associated neuropathy concluded that high-concentration topical capsaicin provided more relief in patients with high pain levels than control patients who received a subtherapeutic (0.04%) capsaicin cream. Number-needed-to-treat values were between 8 and 12. Local adverse events were common, but not consistently reported enough to calculate a number needed to harm.⁴

OA. In randomized trials, capsaicin provided mild-to-moderate efficacy for patients with hand and knee OA, when compared with placebo.^5-7 A systematic review of capsaicin for all osteoarthritic conditions noted that there was consistent evidence that capsaicin gel was effective for OA.⁸ However, a 2013 Cochrane review of only knee OA noted that capsicum extract did not provide significant clinical improvement for pain or function and resulted in a significant number of adverse events.⁹

LBP. Based on a 2014 Cochrane review of three trials (755 subjects) of moderate quality, capsicum frutescens cream or plaster appeared more efficacious than placebo in people with chronic LBP.¹⁰ Based on current (low-quality) evidence in one trial, however, it’s not clear whether topical capsicum cream is more beneficial for acute LBP than placebo.¹⁰

PHN. Topical capsaicin is an FDA-approved treatment for PHN. A review and cost-effectiveness analysis demonstrated that 8% capsaicin had significantly higher effectiveness rates than the oral agents (tricyclic antidepressants, duloxetine, gabapentin, pregabalin) used to treat PHN.¹¹ The cost of the capsaicin patch was similar to a topical lidocaine patch and oral products for PHN.¹¹ A meta-analysis of seven RCTs indicated that 8% topical capsaicin was superior to the low-dose capsaicin patch for relieving pain associated with PHN.¹²

Continue to: Adverse effects

Very few toxic effects have been reported during a half-century of capsaicin use. Those that have been reported are mainly limited to mild local reactions.² The most common adverse effect of topical capsaicin is local irritation (burning, stinging, and erythema), which was reported in approximately 40% of patients.⁶ Nevertheless, more than 90% of the subjects in clinical studies were able to complete the studies, and pain rapidly resolved after patch removal.² Washing with soap and water may help prevent the compound from spreading to other parts of the body unintentionally.

The safety of the patch has been demonstrated with repeated dosing every three months for up to one year. However, the long-term risks of chronic capsaicin use and its effect on epidermal innervation are uncertain.⁵

The bottom line

Capsaicin appears to be an effective treatment for neuropathy and chronic LBP. It is FDA approved for the treatment of PHN. It may also benefit patients with OA and acute LBP. Serious adverse effects are uncommon with topical use. Common adverse effects include burning pain and irritation in the area of application, which can be intense and cause discontinuation.²

Continue to: BUTTERBUR

Petasites hybridus, also known as butterbur, is a member of the daisy family, Asteraceae, and is a perennial plant found throughout Europe and Asia.¹³ It was used as a remedy for ulcers, wounds, and inflammation in ancient Greece. Its calcium channel–blocking effects may counteract vasoconstriction and play a role in preventing hyperexcitation of neurons.¹⁴ Sesquiterpenes, the pharmacologically active compounds in butterbur, have strong anti-inflammatory and vasodilatory effects through lipoxygenase and leukotriene inhibition.¹⁴

Migraine headache. Butterbur appears to be effective in migraine prophylaxis. Several studies have shown butterbur to significantly reduce the number of migraine attacks per month when compared with placebo. In a small, randomized, placebo-controlled, parallel-group study on the efficacy and tolerability of a special butterbur root extract (Petadolex) for the prevention of migraine, response rate was 45% in the butterbur group vs 15% in the placebo group. Butterbur was well tolerated.¹⁵ Similar results were found in another RCT in which butterbur 75 mg bid significantly reduced migraine frequency by 48%, compared with 26% for the placebo group.¹⁶ Butterbur was well tolerated in this study, too, and no serious adverse events occurred. Findings suggest that 75 mg bid may be a good option for migraine prevention, given the agent’s safety profile.

Petadolex may also be a good option in pediatric migraine. A 2005 study in children and adolescents found that 77% of patients experienced a reduction in attacks by at least 50% with butterbur. Patients were treated with 50 mg to 150 mg over four months.¹⁷

In their 2012 guidelines for migraine prevention, the American Academy of Neurology (AAN) and American Headache Society gave butterbur a Level A recommendation, concluding that butterbur should be offered to patients with migraine to reduce the frequency and severity of migraine attacks.¹⁸ However, the AAN changed its position in 2015, redacting the recommendation due to serious safety concerns.¹⁹

Allergic rhinitis. Although the data are not convincing, some studies have shown that butterbur may be beneficial for the treatment of allergic rhinitis.^20,21

Continue to: Adverse effects

While the butterbur plant itself contains pyrrolizidine alkaloids (PA), which are hepatotoxic and carcinogenic, extracts of butterbur root that are almost completely free from these alkaloids are available. Patients who choose to use butterbur should be advised to use only products that are certified and labeled PA free.

Petadolex, the medication used in migraine studies, was initially approved by the German health regulatory authority, but approval was later withdrawn due to concerns about liver toxicity.²² In 2012, the United Kingdom’s Medicines and Health Care Products Regulatory Agency withdrew all butterbur products from the market due to associated cases of liver toxicity.²² Butterbur products are still available in the US market, and the risks and benefits should be discussed with all patients considering this treatment. Liver function monitoring is recommended for all patients using butterbur.²²

The herb can also cause dyspepsia, headache, itchy eyes, gastrointestinal symptoms, asthma, fatigue, and drowsiness. Additionally, people who are allergic to ragweed and daisies may have allergic reactions to butterbur. Eructation (belching) occurred in 7% of patients in a pediatric study.¹⁷

The bottom line

Butterbur appears to be efficacious for migraine prophylaxis, but long-term safety is unknown and serious concerns exist for liver toxicity.

Continue to: GREEN TEA

Most tea leaves come from the Camellia sinensis bush, but green and black tea are processed differently to produce different end products.²³ It is estimated that green tea accounts for approximately a quarter of all tea consumption and is most commonly consumed in Asian countries.²³ The health-promoting effects of green tea are mainly attributed to its polyphenol content.²⁴ Of the many types of tea, green tea has the highest concentration of polyphenols, including catechins, which are powerful antioxidants.^23,24 Green tea has been used in traditional Chinese and Indian medicine to control bleeding, improve digestion, and promote overall health.²³

Dementia. Green tea polyphenols may enhance cognition and may protect against the development of dementia. In-vitro studies have shown that green tea reduces hydrogen peroxide and ß-amyloid peptides, which are significant in the development of Alzheimer’s disease.²⁵ A 12-subject double-blind study found green tea increased working memory and had an impact on frontoparietal brain connections.²⁶ Furthermore, a cohort study with 13,645 Japanese participants over a five-year period found that frequent green tea consumption (> 5 cups per day) was associated with a lower risk for dementia.²⁷ Additional studies are needed, but green tea may be useful in the treatment or prevention of dementia in the future.

Coronary artery disease. In one study, green tea plasma and urinary concen­trations were associated with plasma biomarkers of cardiovascular disease and ­diabetes.²⁸ In one review, the consumption of green tea was associated with a statis­tically significant reduction in LDL cholesterol.²⁹ Furthermore, a 2015 systematic review and meta-analysis of prospective observational studies concluded that increased tea consumption (of any type) is associated with a reduced risk for coronary heart disease, cardiac death, stroke, and total mortality.³⁰

Cancer. Many studies have shown that green tea may reduce the risk for cancer, although epidemiologic evidence is inconsistent. Studies have shown that cancer rates tend to be lower in those who consume higher levels of green tea.^31,32 Whether this can be attributed solely to green tea remains debatable. Several other studies have shown that polyphenols in green tea can inhibit the growth of cancer cells, but the exact mechanism by which tea interacts with cancerous cells is unknown.²³

Several population-based studies have been performed, mostly in Japan, which showed green tea consumption reduced the risk for cancer. Fewer prostate cancer cases have been reported in men who consume green tea.³³ While studies have been performed to determine whether green tea has effects on pancreatic, esophageal, ovarian, breast, bladder, and colorectal cancer, the evidence remains inadequate.³²

Diabetes. Green tea has been shown in several studies to have a beneficial effect on diabetes. A retrospective Japanese cohort study showed that those who consumed green tea were one-third less likely to develop type 2 diabetes.³⁴ A 10-year study from Taiwan found lower body fat and smaller waist circumference in those who consumed green tea regularly.³⁵ A 2014 meta-analysis and systematic review of tea (any type) consumption and the risk for diabetes concluded that three or more cups of tea per day was associated with a lower risk for diabetes.³⁶ Another meta-analysis of 17 RCTs focused on green tea concluded that green tea improves glucose control and A1C values.³⁷

Continue to: Adverse effects

There have been concerns about potential hepatotoxicity induced by green tea intake.³⁸ However, a systematic review of 34 RCTs on liver-related adverse events from green tea showed only a slight elevation in liver function tests; no serious liver-related adverse events were reported.³⁸ This review suggested that liver-related adverse events after intake of green tea extracts are rare.³⁸

Consuming green tea in the diet may lower the risk for adverse effects since the concentration consumed is generally much lower than that found in extracts.

Contraindications to drinking green tea are few. Individuals with caffeine sensitivities could experience insomnia, anxiety, irritability, or upset stomach. Additionally, patients who are taking anticoagulation drugs, such as warfarin, should avoid green tea due to its vitamin K content, which can counter the effects of warfarin. Pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should use caution with green tea consumption.

The bottom line

Green tea consumption in the diet appears to be safe and may have beneficial effects on weight, dementia, and risk for diabetes, cancer, and cardiovascular disease. Patients may want to consider drinking green tea as part of a healthy diet, in combination with exercise.

Continue to: PEPPERMINT

Mentha piperita, also known as peppermint, is a hybrid between water mint and spearmint. It is found throughout Europe and North America and is commonly used in tea and toothpaste and as a flavoring for gum. Menthol and methyl salicylate are the main active ingredients in peppermint, and peppermint has calcium channel–blocker effects.³⁹ Menthol has been shown to help regulate cold and pain sensation through the TRPM8 receptor.⁴⁰ The peppermint herb is used both orally and topically, and has been studied in the treatment of multiple conditions.

Irritable bowel syndrome (IBS). It appears that peppermint inhibits spontaneous peristaltic activity, which reduces gastric emptying, decreases basal tone in the gastrointestinal tract, and slows down peristalsis in the gut.³⁹

The American College of Gastroenterology guidelines currently note that there is moderate-quality evidence for peppermint oil in the treatment of IBS.⁴¹ A Cochrane review concluded that peppermint appears to be beneficial for IBS-related symptoms and pain.⁴² In a systematic review of nine studies from 2014, peppermint oil was found to be more effective than placebo for IBS symptoms such as pain, bloating, gas, and diarrhea.⁴³ The review also indicated that peppermint oil is safe, with heartburn being the most common complaint.⁴³ A 2016 study also found that triple-coated microspheres containing peppermint oil reduced the frequency and intensity of IBS symptoms.⁴⁴

Non-ulcer dyspepsia. In combination with caraway oil, peppermint oil can be used to reduce symptoms of non-ulcer dyspepsia.^45,46 A multicenter, randomized, placebo-controlled, double-blind study found that 43.3% of subjects improved with a peppermint-caraway oil combination after eight weeks, compared with 3.5% receiving placebo.⁴⁶

Barium enema–related colonic spasm. Peppermint can relax the lower esophageal sphincter, and it has been shown to be useful as an antispasmodic agent for barium enema–related colonic spasm.^47,48

Itching/skin irritation. Peppermint, when applied topically, has been used to calm pruritus and relieve irritation and inflammation. It has a soothing and cooling effect on the skin. At least one study found it to be effective in the treatment of pruritus gravidarum, although the study population consisted of only 96 subjects.⁴⁹

Migraine headache. Initial small trials suggest that menthol is likely beneficial for migraine headaches. A pilot trial of 25 patients treated with topical menthol 6% gel for an acute migraine attack showed a significant improvement in headache intensity two hours after gel application.⁵⁰ In a randomized, triple-blind, placebo-controlled, crossover study of 35 patients, a menthol 10% solution was shown to be more efficacious as abortive treatment of migraine headaches than placebo.⁵¹

Tension headache. In a randomized, placebo-controlled, double-blind crossover study, topical peppermint oil showed a significant clinical reduction in tension headache pain.⁵² Another small, randomized, double-blind trial showed that tiger balm (containing menthol as the main ingredient) also produced statistically significant improvement in tension headache discomfort compared with placebo.⁵³

Continue to: Musculoskeletal pain

Musculoskeletal pain. A small study comparing topical menthol to ice for muscle soreness noted decreased perceived discomfort with menthol.⁵⁴ Menthol has also been shown to reduce pain in patients with knee OA.⁵⁵

Carpal tunnel syndrome (CTS). A triple-blind RCT concluded that topical menthol acutely reduced pain intensity in slaughterhouse workers with CTS, and it should be considered as an effective nonsystemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.⁵⁶

Adverse effects

Peppermint appears to be safe for most adults when used in small doses, and serious adverse effects are rare.^43,57 While peppermint tea appears to be safe in moderate-to-large amounts, people allergic to plants in the peppermint family (eg, mint, thyme, sage, rosemary, marjoram, basil, lavender) may experience allergic reactions with swelling, wheals, or erythema. Peppermint may also cause heartburn due to relaxation of the cardiac sphincter.

Other symptoms may include nausea, vomiting, flushing, and headache.⁵⁸ The herb may also be both hepatotoxic and nephrotoxic at extremely high doses.⁵⁹ Other considerations for women are that it can trigger menstruation and should be avoided during pregnancy. Due to uncertain efficacy in this population, peppermint oil should not be used on the face of infants, young children, or pregnant women.^58,59

The bottom line

Peppermint appears to be safe and well tolerated. It is useful in alleviating IBS symptoms and may be effective in the treatment of non-ulcerative dyspepsia, musculoskeletal pain, headache, and CTS.^54,55

The National Center for Complementary and Integrative Health, a division of the National Institutes of Medicine, estimates that 38% of American adults use complementary and alternative medicine (including 17.7% who say they use “natural products”).¹ Despite the popularity of these products, many providers remain skeptical—and for good reason. Enthusiasts may offer dramatic anecdotes to “prove” their supplements’ worth, but little scientific support is available for most herbal remedies. There are, however, exceptions—capsaicin, butterbur, green tea, and peppermint—as this review of the medical literature reveals.

Worth noting as you consider this—or any—review of herbals is that while there is limited scientific evidence to establish the safety and efficacy of most herbal products, they are nonetheless freely sold without FDA approval because, under current regulations, they are considered dietary supplements. That legal designation means companies can manufacture, sell, and market herbs without first demonstrating safety and efficacy, as is required for pharmaceutical drugs. Because herbal medications do not require the same testing through the large randomized controlled trials (RCTs) required for pharmaceuticals, evidence is often based on smaller RCTs and other studies of lower overall quality. Despite these limitations, we believe it’s worth keeping an open mind about the value of evidence-based herbal and botanical treatments.

CAPSAICIN

Capsaicin, an active compound in chili peppers, provokes a burning sensation but also has a long history of use in pain treatment.² Qutenza, an FDA-approved, chemically synthesized 8% capsaicin patch, is identical to the naturally occurring molecule.² Topical capsaicin exerts its therapeutic effect by rapidly depleting substance P, thus reducing the transmission of pain from C fibers to higher neurologic centers in the area of administration.³

Meta-analyses and systematic reviews have shown capsaicin is effective for various painful conditions, including peripheral diabetic neuropathy, osteoarthritis (OA), low back pain (LBP), and postherpetic neuralgia (PHN).

Peripheral neuropathy. A Cochrane review of six randomized, double-blind, placebo-controlled studies of at least six weeks’ duration using topical 8% capsaicin to treat PHN and HIV-associated neuropathy concluded that high-concentration topical capsaicin provided more relief in patients with high pain levels than control patients who received a subtherapeutic (0.04%) capsaicin cream. Number-needed-to-treat values were between 8 and 12. Local adverse events were common, but not consistently reported enough to calculate a number needed to harm.⁴

OA. In randomized trials, capsaicin provided mild-to-moderate efficacy for patients with hand and knee OA, when compared with placebo.^5-7 A systematic review of capsaicin for all osteoarthritic conditions noted that there was consistent evidence that capsaicin gel was effective for OA.⁸ However, a 2013 Cochrane review of only knee OA noted that capsicum extract did not provide significant clinical improvement for pain or function and resulted in a significant number of adverse events.⁹

LBP. Based on a 2014 Cochrane review of three trials (755 subjects) of moderate quality, capsicum frutescens cream or plaster appeared more efficacious than placebo in people with chronic LBP.¹⁰ Based on current (low-quality) evidence in one trial, however, it’s not clear whether topical capsicum cream is more beneficial for acute LBP than placebo.¹⁰

PHN. Topical capsaicin is an FDA-approved treatment for PHN. A review and cost-effectiveness analysis demonstrated that 8% capsaicin had significantly higher effectiveness rates than the oral agents (tricyclic antidepressants, duloxetine, gabapentin, pregabalin) used to treat PHN.¹¹ The cost of the capsaicin patch was similar to a topical lidocaine patch and oral products for PHN.¹¹ A meta-analysis of seven RCTs indicated that 8% topical capsaicin was superior to the low-dose capsaicin patch for relieving pain associated with PHN.¹²

Continue to: Adverse effects

Very few toxic effects have been reported during a half-century of capsaicin use. Those that have been reported are mainly limited to mild local reactions.² The most common adverse effect of topical capsaicin is local irritation (burning, stinging, and erythema), which was reported in approximately 40% of patients.⁶ Nevertheless, more than 90% of the subjects in clinical studies were able to complete the studies, and pain rapidly resolved after patch removal.² Washing with soap and water may help prevent the compound from spreading to other parts of the body unintentionally.

The safety of the patch has been demonstrated with repeated dosing every three months for up to one year. However, the long-term risks of chronic capsaicin use and its effect on epidermal innervation are uncertain.⁵

The bottom line

Capsaicin appears to be an effective treatment for neuropathy and chronic LBP. It is FDA approved for the treatment of PHN. It may also benefit patients with OA and acute LBP. Serious adverse effects are uncommon with topical use. Common adverse effects include burning pain and irritation in the area of application, which can be intense and cause discontinuation.²

Continue to: BUTTERBUR

Petasites hybridus, also known as butterbur, is a member of the daisy family, Asteraceae, and is a perennial plant found throughout Europe and Asia.¹³ It was used as a remedy for ulcers, wounds, and inflammation in ancient Greece. Its calcium channel–blocking effects may counteract vasoconstriction and play a role in preventing hyperexcitation of neurons.¹⁴ Sesquiterpenes, the pharmacologically active compounds in butterbur, have strong anti-inflammatory and vasodilatory effects through lipoxygenase and leukotriene inhibition.¹⁴

Migraine headache. Butterbur appears to be effective in migraine prophylaxis. Several studies have shown butterbur to significantly reduce the number of migraine attacks per month when compared with placebo. In a small, randomized, placebo-controlled, parallel-group study on the efficacy and tolerability of a special butterbur root extract (Petadolex) for the prevention of migraine, response rate was 45% in the butterbur group vs 15% in the placebo group. Butterbur was well tolerated.¹⁵ Similar results were found in another RCT in which butterbur 75 mg bid significantly reduced migraine frequency by 48%, compared with 26% for the placebo group.¹⁶ Butterbur was well tolerated in this study, too, and no serious adverse events occurred. Findings suggest that 75 mg bid may be a good option for migraine prevention, given the agent’s safety profile.

Petadolex may also be a good option in pediatric migraine. A 2005 study in children and adolescents found that 77% of patients experienced a reduction in attacks by at least 50% with butterbur. Patients were treated with 50 mg to 150 mg over four months.¹⁷

In their 2012 guidelines for migraine prevention, the American Academy of Neurology (AAN) and American Headache Society gave butterbur a Level A recommendation, concluding that butterbur should be offered to patients with migraine to reduce the frequency and severity of migraine attacks.¹⁸ However, the AAN changed its position in 2015, redacting the recommendation due to serious safety concerns.¹⁹

Allergic rhinitis. Although the data are not convincing, some studies have shown that butterbur may be beneficial for the treatment of allergic rhinitis.^20,21

Continue to: Adverse effects

While the butterbur plant itself contains pyrrolizidine alkaloids (PA), which are hepatotoxic and carcinogenic, extracts of butterbur root that are almost completely free from these alkaloids are available. Patients who choose to use butterbur should be advised to use only products that are certified and labeled PA free.

Petadolex, the medication used in migraine studies, was initially approved by the German health regulatory authority, but approval was later withdrawn due to concerns about liver toxicity.²² In 2012, the United Kingdom’s Medicines and Health Care Products Regulatory Agency withdrew all butterbur products from the market due to associated cases of liver toxicity.²² Butterbur products are still available in the US market, and the risks and benefits should be discussed with all patients considering this treatment. Liver function monitoring is recommended for all patients using butterbur.²²

The herb can also cause dyspepsia, headache, itchy eyes, gastrointestinal symptoms, asthma, fatigue, and drowsiness. Additionally, people who are allergic to ragweed and daisies may have allergic reactions to butterbur. Eructation (belching) occurred in 7% of patients in a pediatric study.¹⁷

The bottom line

Butterbur appears to be efficacious for migraine prophylaxis, but long-term safety is unknown and serious concerns exist for liver toxicity.

Continue to: GREEN TEA

Most tea leaves come from the Camellia sinensis bush, but green and black tea are processed differently to produce different end products.²³ It is estimated that green tea accounts for approximately a quarter of all tea consumption and is most commonly consumed in Asian countries.²³ The health-promoting effects of green tea are mainly attributed to its polyphenol content.²⁴ Of the many types of tea, green tea has the highest concentration of polyphenols, including catechins, which are powerful antioxidants.^23,24 Green tea has been used in traditional Chinese and Indian medicine to control bleeding, improve digestion, and promote overall health.²³

Dementia. Green tea polyphenols may enhance cognition and may protect against the development of dementia. In-vitro studies have shown that green tea reduces hydrogen peroxide and ß-amyloid peptides, which are significant in the development of Alzheimer’s disease.²⁵ A 12-subject double-blind study found green tea increased working memory and had an impact on frontoparietal brain connections.²⁶ Furthermore, a cohort study with 13,645 Japanese participants over a five-year period found that frequent green tea consumption (> 5 cups per day) was associated with a lower risk for dementia.²⁷ Additional studies are needed, but green tea may be useful in the treatment or prevention of dementia in the future.

Coronary artery disease. In one study, green tea plasma and urinary concen­trations were associated with plasma biomarkers of cardiovascular disease and ­diabetes.²⁸ In one review, the consumption of green tea was associated with a statis­tically significant reduction in LDL cholesterol.²⁹ Furthermore, a 2015 systematic review and meta-analysis of prospective observational studies concluded that increased tea consumption (of any type) is associated with a reduced risk for coronary heart disease, cardiac death, stroke, and total mortality.³⁰

Cancer. Many studies have shown that green tea may reduce the risk for cancer, although epidemiologic evidence is inconsistent. Studies have shown that cancer rates tend to be lower in those who consume higher levels of green tea.^31,32 Whether this can be attributed solely to green tea remains debatable. Several other studies have shown that polyphenols in green tea can inhibit the growth of cancer cells, but the exact mechanism by which tea interacts with cancerous cells is unknown.²³

Several population-based studies have been performed, mostly in Japan, which showed green tea consumption reduced the risk for cancer. Fewer prostate cancer cases have been reported in men who consume green tea.³³ While studies have been performed to determine whether green tea has effects on pancreatic, esophageal, ovarian, breast, bladder, and colorectal cancer, the evidence remains inadequate.³²

Diabetes. Green tea has been shown in several studies to have a beneficial effect on diabetes. A retrospective Japanese cohort study showed that those who consumed green tea were one-third less likely to develop type 2 diabetes.³⁴ A 10-year study from Taiwan found lower body fat and smaller waist circumference in those who consumed green tea regularly.³⁵ A 2014 meta-analysis and systematic review of tea (any type) consumption and the risk for diabetes concluded that three or more cups of tea per day was associated with a lower risk for diabetes.³⁶ Another meta-analysis of 17 RCTs focused on green tea concluded that green tea improves glucose control and A1C values.³⁷

Continue to: Adverse effects

There have been concerns about potential hepatotoxicity induced by green tea intake.³⁸ However, a systematic review of 34 RCTs on liver-related adverse events from green tea showed only a slight elevation in liver function tests; no serious liver-related adverse events were reported.³⁸ This review suggested that liver-related adverse events after intake of green tea extracts are rare.³⁸

Consuming green tea in the diet may lower the risk for adverse effects since the concentration consumed is generally much lower than that found in extracts.

Contraindications to drinking green tea are few. Individuals with caffeine sensitivities could experience insomnia, anxiety, irritability, or upset stomach. Additionally, patients who are taking anticoagulation drugs, such as warfarin, should avoid green tea due to its vitamin K content, which can counter the effects of warfarin. Pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should use caution with green tea consumption.

The bottom line

Green tea consumption in the diet appears to be safe and may have beneficial effects on weight, dementia, and risk for diabetes, cancer, and cardiovascular disease. Patients may want to consider drinking green tea as part of a healthy diet, in combination with exercise.

Continue to: PEPPERMINT

Mentha piperita, also known as peppermint, is a hybrid between water mint and spearmint. It is found throughout Europe and North America and is commonly used in tea and toothpaste and as a flavoring for gum. Menthol and methyl salicylate are the main active ingredients in peppermint, and peppermint has calcium channel–blocker effects.³⁹ Menthol has been shown to help regulate cold and pain sensation through the TRPM8 receptor.⁴⁰ The peppermint herb is used both orally and topically, and has been studied in the treatment of multiple conditions.

Irritable bowel syndrome (IBS). It appears that peppermint inhibits spontaneous peristaltic activity, which reduces gastric emptying, decreases basal tone in the gastrointestinal tract, and slows down peristalsis in the gut.³⁹

The American College of Gastroenterology guidelines currently note that there is moderate-quality evidence for peppermint oil in the treatment of IBS.⁴¹ A Cochrane review concluded that peppermint appears to be beneficial for IBS-related symptoms and pain.⁴² In a systematic review of nine studies from 2014, peppermint oil was found to be more effective than placebo for IBS symptoms such as pain, bloating, gas, and diarrhea.⁴³ The review also indicated that peppermint oil is safe, with heartburn being the most common complaint.⁴³ A 2016 study also found that triple-coated microspheres containing peppermint oil reduced the frequency and intensity of IBS symptoms.⁴⁴

Non-ulcer dyspepsia. In combination with caraway oil, peppermint oil can be used to reduce symptoms of non-ulcer dyspepsia.^45,46 A multicenter, randomized, placebo-controlled, double-blind study found that 43.3% of subjects improved with a peppermint-caraway oil combination after eight weeks, compared with 3.5% receiving placebo.⁴⁶

Barium enema–related colonic spasm. Peppermint can relax the lower esophageal sphincter, and it has been shown to be useful as an antispasmodic agent for barium enema–related colonic spasm.^47,48

Itching/skin irritation. Peppermint, when applied topically, has been used to calm pruritus and relieve irritation and inflammation. It has a soothing and cooling effect on the skin. At least one study found it to be effective in the treatment of pruritus gravidarum, although the study population consisted of only 96 subjects.⁴⁹

Migraine headache. Initial small trials suggest that menthol is likely beneficial for migraine headaches. A pilot trial of 25 patients treated with topical menthol 6% gel for an acute migraine attack showed a significant improvement in headache intensity two hours after gel application.⁵⁰ In a randomized, triple-blind, placebo-controlled, crossover study of 35 patients, a menthol 10% solution was shown to be more efficacious as abortive treatment of migraine headaches than placebo.⁵¹

Tension headache. In a randomized, placebo-controlled, double-blind crossover study, topical peppermint oil showed a significant clinical reduction in tension headache pain.⁵² Another small, randomized, double-blind trial showed that tiger balm (containing menthol as the main ingredient) also produced statistically significant improvement in tension headache discomfort compared with placebo.⁵³

Continue to: Musculoskeletal pain

Musculoskeletal pain. A small study comparing topical menthol to ice for muscle soreness noted decreased perceived discomfort with menthol.⁵⁴ Menthol has also been shown to reduce pain in patients with knee OA.⁵⁵

Carpal tunnel syndrome (CTS). A triple-blind RCT concluded that topical menthol acutely reduced pain intensity in slaughterhouse workers with CTS, and it should be considered as an effective nonsystemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.⁵⁶

Adverse effects

Peppermint appears to be safe for most adults when used in small doses, and serious adverse effects are rare.^43,57 While peppermint tea appears to be safe in moderate-to-large amounts, people allergic to plants in the peppermint family (eg, mint, thyme, sage, rosemary, marjoram, basil, lavender) may experience allergic reactions with swelling, wheals, or erythema. Peppermint may also cause heartburn due to relaxation of the cardiac sphincter.

Other symptoms may include nausea, vomiting, flushing, and headache.⁵⁸ The herb may also be both hepatotoxic and nephrotoxic at extremely high doses.⁵⁹ Other considerations for women are that it can trigger menstruation and should be avoided during pregnancy. Due to uncertain efficacy in this population, peppermint oil should not be used on the face of infants, young children, or pregnant women.^58,59

The bottom line

Peppermint appears to be safe and well tolerated. It is useful in alleviating IBS symptoms and may be effective in the treatment of non-ulcerative dyspepsia, musculoskeletal pain, headache, and CTS.^54,55

The National Center for Complementary and Integrative Health, a division of the National Institutes of Medicine, estimates that about 38% of American adults use complementary and alternative medicine.¹ That statistic includes 17.7% who say they use natural products. Despite their popularity, many physicians remain skeptical—and for good reason. Enthusiasts frequently offer dramatic anecdotes to “prove” their supplements' worth, but little scientific support is available for most herbal remedies. There are, however, exceptions. As this review of the medical literature will reveal, there is evidence to support the use of capsaicin to relieve osteoarthritis (OA) and postherpetic neuralgia (PHN) and support for green tea to serve as a lipid-lowering agent and help treat diabetes. Similarly, researchers have found that peppermint may be of value in the management of irritable bowel syndrome (IBS). (We also review the literature on butterbur for migraine headaches, but serious safety issues exist; TABLE.)

In the second part of this series, which is available here, we explore what the evidence tells us about the use of turmeric, chamomile, rosemary, coffee, and cocoa.

Worth noting as you consider this—or any—review of herbals is that while there is limited scientific evidence to establish the safety and efficacy of most herbal products, they are nonetheless freely sold without US Food & Drug Administration (FDA) approval because under current regulations, they are considered dietary supplements. That legal designation means companies can manufacture, sell, and market herbs without first demonstrating safety and efficacy, as is required for pharmaceutical drugs. Because herbal medications do not require the same testing through the large randomized controlled trials (RCTs) required for pharmaceuticals, evidence is often based on smaller RCTs and other studies of lower overall quality. Despite these limitations, we believe it’s worth keeping an open mind about the value of evidence-based herbal and botanical treatments.

Overview

Capsaicin, an active compound in chili peppers, provokes a burning sensation, but also has a long history of use in pain treatment.² Qutenza, an FDA-approved chemically synthesized 8% capsaicin patch, is identical to the naturally occurring molecule.² Topically applied capsaicin exerts its therapeutic effect by rapidly depleting substance P, thus reducing the transmission of pain from C fibers to higher neurologic centers in the area of administration.³

Capsaicin provided mild to moderate efficacy in randomized trials for patients with hand and knee OA when compared with placebo.

Meta-analyses and systematic reviews have shown capsaicin is effective for various painful conditions, including peripheral diabetic neuropathy, OA, and PHN.

Peripheral neuropathy. A Cochrane review of 6 randomized, double-blind, placebo-controlled studies of at least 6 weeks' duration using topical 8% capsaicin to treat neuropathic pain concluded that high-concentration topical capsaicin used to treat PHN and human immunodeficiency virus (HIV)-associated neuropathy provided more relief in patients with high pain levels than control patients who received placebo, which was a subtherapeutic (0.04%) capsaicin cream. Number-needed-to-treat values were between 8 and 12. Local adverse events were common, but not consistently reported enough to calculate a number needed to harm.⁴

OA. Capsaicin provides mild to moderate efficacy in randomized trials for patients with hand and knee OA, when compared with placebo.^5-7 A systematic review of capsaicin for all osteoarthritic conditions noted that there was consistent evidence that capsaicin gel was effective for OA.⁸ However, a 2013 Cochrane review of only knee OA noted that capsicum extract did not provide significant clinical improvement for pain or function in knee OA and resulted in a significant number of adverse events.⁹

Low back pain (LBP). Based on a 2014 Cochrane review of 3 trials (755 subjects) of moderate quality, capsicum frutescens cream or plaster appeared more efficacious than placebo in people with chronic LBP.¹⁰ Based on current (low-quality) evidence in one trial, however, it’s not clear whether topical capsicum cream is more beneficial for acute LBP than a placebo.¹⁰

PHN. Topical 8% capsaicin is an FDA-approved treatment for PHN. A review and cost-effectiveness analysis demonstrated that 8% capsaicin had significantly higher effectiveness rates than the oral agents (tricyclic antidepressants, duloxetine, gabapentin, pregabalin) used to treat PHN.¹¹ In addition, the cost-effectiveness analysis found that the capsaicin patch was similar in cost to a topical lidocaine patch and oral products for PHN.¹¹

A meta-analysis of 7 RCTs indicated that 8% topical capsaicin was superior to the low-dose capsaicin patch for relieving pain associated with PHN.¹²

Adverse effects

Very few toxic effects have been reported during a half century of capsaicin use. Those that have been reported are mainly limited to mild local reactions.² The most common adverse effect of topical capsaicin is local irritation (burning, stinging, and erythema), which had been reported to occur in approximately 40% of patients.⁶ Nevertheless, more than 90% of the subjects in clinical studies were able to complete the studies, and pain rapidly resolved after patch removal.² Washing with soap and water may help prevent the compound from spreading to other parts of the body unintentionally.

The safety of the patch has been demonstrated with repeated dosing every 3 months for up to one year. However, the long-term risks of chronic capsaicin use and its effect on epidermal innervation are uncertain.⁵

The bottom line

Capsaicin appears to be an effective treatment for neuropathy and chronic LBP. It is FDA approved for the treatment of PHN. It may also benefit patients with OA and acute LBP. Serious adverse effects are uncommon with topical use. Common adverse effects include burning pain and irritation in the area of application, which can be intense and cause discontinuation.²

Overview

Petasites hybridus, also known as butterbur, is a member of the daisy family, Asteraceae, and is a perennial plant found throughout Europe and Asia.¹³ It was used as a remedy for ulcers, wounds, and inflammation in ancient Greece. Its calcium channel-blocking effects may counteract vasoconstriction and play a role in preventing hyper-excitation of neurons.¹⁴ Sesquiterpenes, the pharmacologically active compounds in butterbur, have strong anti-inflammatory and vasodilatory effects through lipoxygenase and leukotriene inhibition.¹⁴

Migraine headache. Butterbur appears to be effective in migraine prophylaxis. Several studies have shown butterbur to significantly reduce the number of migraine attacks per month when compared with placebo. In a small, randomized, placebo-controlled, parallel-group study on the efficacy and tolerability of a special butterbur root extract (Petadolex) for the prevention of migraine, response rate was 45% in the butterbur group vs 15% in the placebo group. Butterbur was well tolerated.¹⁵ Similar results were found in another RCT in which Petasites (butterbur) 75 mg bid significantly reduced migraine attack frequency by 48%, compared with 26% for the placebo group.¹⁶ Petadolex was well tolerated in this study, too, and no serious adverse events occurred. Findings suggest that 75 mg bid may be a good option for migraine prevention given the agent's safety profile.

Butterbur appears to be effective in migraine prophylaxis, but there are serious concerns about liver toxicity.

Petadolex may also be a good option in pediatric migraine. A 2005 study in children and adolescents found that 77% of patients experienced a reduction in attacks by at least 50% with butterbur. Patients were treated with 50 mg to 150 mg over 4 months.¹⁷

In their guidelines for migraine prevention, the American Academy of Neurology (AAN) and American Headache Society gave butterbur a Level A recommendation and concluded that butterbur should be offered to patients with migraine to reduce the frequency and severity of migraine attacks.¹⁸ However, the AAN has since changed its position, stating that “The 2012 AAN guideline, ‘Evidence-based guideline update: NSAIDS and other complementary treatments for episodic migraine prevention in adults’ has been retired by the AAN Board of Directors on September 16, 2015, due to serious safety concerns with a preventative treatment, butterbur, recommended by this guideline. The recommendations and conclusions in all retired guidelines are considered no longer valid and no longer supported by the AAN.”¹⁹

Allergic rhinitis. Although the data is not convincing, some studies have shown that butterbur may be beneficial for the treatment of allergic rhinitis.^20,21

Adverse effects

While the butterbur plant itself contains pyrrolizidine alkaloids (PA), which are hepatotoxic and carcinogenic, extracts of butterbur root that are almost completely free from these alkaloids are available. (Patients who choose to use butterbur should be advised to use only products that are certified and labeled pyrrolizidine alkaloids free.)

Petadolex, the medication used in migraine studies, was initially approved by the German health regulatory authority, but approval was later withdrawn due to concerns about liver toxicity.²² In 2012, the United Kingdom’s Medicines and Health Care Products Regulatory Agency withdrew all butterbur products from the market due to associated cases of liver toxicity.²² Petasites (butterbur) products are still available in the US market, and the risks and benefits should be discussed with all patients considering this treatment. Liver function monitoring is recommended for all patients using butterbur.²²

The herb can also cause dyspepsia, headache, itchy eyes, gastrointestinal symptoms, asthma, fatigue, and drowsiness. Additionally, people who are allergic to ragweed and daisies may have allergic reactions to butterbur. Eructation (belching) occurred in 7% of patients in a pediatric study.¹⁷

The bottom line

Butterbur appears to be efficacious for migraine prophylaxis, but long-term safety is unknown and serious concerns exist for liver toxicity.

Overview

Most tea leaves come from the Camellia sinensis bush, but green and black tea are processed differently to produce different end products.²³ It is estimated that green tea accounts for approximately a quarter of all tea consumption, and is most commonly consumed in Asian countries.²³ The health-promoting effects of green tea are mainly attributed to its polyphenol content.²⁴ While there are many types of tea due to how they are processed, green tea has the highest concentration of polyphenols, including catechins, which are powerful antioxidants.^23,24 Green tea has been used in traditional Chinese and Indian medicine to control bleeding, improve digestion, and promote overall health.²³

Dementia. Green tea polyphenols may enhance cognition and may protect against the development of dementia. In-vitro studies have shown that green tea reduces hydrogen peroxide and beta-amyloid peptides, which are significant in the development of Alzheimer’s disease.²⁵ A 12-subject double-blind study found green tea increased working memory and had an impact on frontoparietal brain connections.²⁶ Furthermore, a cohort study with 13,645 Japanese participants over a 5-year period found that frequent green tea consumption (>5 cups per day) was associated with a lower risk of dementa.²⁷ Additional studies are needed, but green tea may be useful in the treatment or prevention of dementia in the future.

Coronary artery disease. In one study, green tea plasma and urinary concentrations were associated with plasma biomarkers of cardiovascular disease and diabetes.²⁸ In one review, the consumption of green tea was associated with a statistically significant reduction in low-density lipoprotein cholesterol.²⁹ Furthermore, a 2015 systematic review and meta-analysis of prospective observational studies concluded that increased tea consumption (of any type) is associated with a reduced risk of coronary heart disease, cardiac death, stroke, and total mortality.³⁰

Cancer. Many studies have shown that green tea may reduce the risk of cancer development, although epidemiologic evidence is inconsistent. Studies have shown that cancer rates tend to be lower in those who consume higher levels of green tea.^31,32 Whether this can be attributed solely to green tea remains debatable. Several other studies have shown that polyphenols in green tea can inhibit the growth of cancer cells, but the exact mechanisms by which tea interacts with cancerous cells is unknown.²³

Many studies have shown that green tea may reduce the risk of cancer development, although epidemiologic evidence is inconsistent.

Several population-based studies have been performed, mostly in Japan, which showed green tea consumption reduced the risk of developing cancer. Fewer prostate cancer cases have been reported in men who consume green tea.³³ While studies have been performed to determine whether green tea has effects on pancreatic, esophageal, ovarian, breast, bladder, and colorectal cancer, the evidence remains inadequate.³²

Diabetes. Green tea has been shown in several studies to have a beneficial effect on diabetes. A retrospective Japanese cohort study showed that those who consumed green tea were one-third less likely to develop type 2 diabetes mellitus.³⁴ A 10-year study from Taiwan found lower body fat and smaller waist circumference in those who consumed green tea regularly.³⁵ A 2014 meta-analysis and systematic review of tea (any type) consumption and the risk of diabetes concluded that 3 cups or more of tea per day was associated with a lower risk of diabetes.³⁶ Another meta-analysis that included 17 RCTs and that focused on green tea concluded that green tea improves glucose control and A1C values.³⁷

Adverse effects

There have been concerns about potential hepatotoxicity induced by green tea intake.³⁸ However, a systematic review of 34 RCTs on liver-related adverse events from green tea showed only a slight elevation in liver function tests; no serious liver-related adverse events were reported.³⁸ This review suggested that liver-related adverse events after intake of green tea extracts are rare.³⁸

A meta-analysis that included 17 RCTs found that green tea improves glucose control and A1C values.

Consuming green tea in the diet may lower the risk of adverse effects since the concentration consumed is generally much lower than that found in extracts.

Contraindications to drinking green tea are few. Individuals with caffeine sensitivities could experience insomnia, anxiety, irritability, or upset stomach. Additionally, patients who are taking anticoagulation drugs, such as warfarin, should avoid green tea due to its vitamin K content, which can counter the effects of warfarin. Pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should use caution with green tea consumption.

The bottom line

Green tea consumption in the diet appears to be safe and may have beneficial effects on weight, diabetes mellitus risk, cancer risk, dementia, and cardiovascular risk. Patients may want to consider drinking green tea as part of a healthy diet, in combination with exercise.

Overview

Mentha piperita, also known as peppermint, is a hybrid between water mint and spearmint. It is found throughout Europe and North America and is commonly used in tea and toothpaste and as a flavoring for gum. It is used both orally and topically. Menthol and methyl salicylate are the main active ingredients in peppermint, and peppermint has calcium channel-blocker effects.³⁹ Menthol has been shown to help regulate cold and pain sensation through the TRPM8 receptor.⁴⁰ The peppermint herb has been studied in the treatment of multiple conditions.

IBS. It appears that peppermint inhibits spontaneous peristaltic activity, which reduces gastric emptying, decreases basal tone in the gastrointestinal tract, and slows down peristalsis in the gut.³⁹

The American College of Gastroenterology guidelines currently note that there is moderate-quality evidence for peppermint oil in the treatment of IBS.⁴¹ A Cochrane review concluded that peppermint appears to be beneficial for IBS-related symptoms and pain.⁴² In a systematic review of 9 studies from 2014, peppermint oil was found to be more effective than placebo for IBS symptoms such as pain, bloating, gas, and diarrhea.⁴³ The review also indicated that peppermint oil is safe, with heartburn being the most common complaint.⁴³ A 2016 study also found that triple-coated microspheres containing peppermint oil reduced the frequency and intensity of IBS symptoms.⁴⁴

Non-ulcer dyspepsia. In combination with caraway oil, peppermint oil can be used to reduce symptoms of non-ulcer dyspepsia.^45,46 A multicenter, randomized, placebo-controlled, double-blind study found that 43.3% of subjects improved with a peppermint-caraway oil combination after 8 weeks, compared with 3.5% receiving placebo.⁴⁶

Barium enema-related colonic spasm. Peppermint can relax the lower esophageal sphincter, and it has been shown to be useful as an antispasmodic agent for barium enema-related colonic spasm.^47,48

Itching/skin irritation. Peppermint, when applied topically, has been used to calm pruritus and relieve irritation and inflammation. It has a soothing and cooling effect on the skin. At least one study found it to be effective in the treatment of pruritus gravidarum, although the study population consisted of only 96 subjects.⁴⁹

Migraine headache. Initial small trials suggest that menthol is likely beneficial for migraine headaches. A pilot trial of 25 patients treated with topical menthol 6% gel for an acute migraine attack showed a significant improvement in headache intensity by 2 hours after gel application.⁵⁰ In a randomized, triple-blind, placebo-controlled, crossover study of 35 patients, a menthol 10% solution was shown to be more efficacious as abortive treatment of migraine headaches than placebo.⁵¹

Tension headache. A randomized, placebo-controlled double-blind crossover study of topical peppermint oil showed a significant clinical reduction in tension headache pain.⁵² Another small randomized, double-blind trial showed that tiger balm (containing menthol as the main ingredient) also produced statistically significant improvement in tension headache discomfort compared with placebo.⁵³

Musculoskeletal pain. A small study comparing topical menthol to ice for muscle soreness noted decreased perceived discomfort with menthol.⁵⁴ Menthol has also been shown to reduce pain in patients with knee OA.⁵⁵

Carpal tunnel syndrome (CTS). A triple-blind, randomized, placebo-controlled trial concluded that topical menthol acutely reduced pain intensity during the working day in slaughterhouse workers with CTS and should be considered as an effective non-systemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.⁵⁶

Adverse effects

Peppermint appears to be safe for most adults when used in small doses, and serious adverse effects are rare.^43,57 While peppermint tea appears to be safe in moderate to large amounts, people allergic to plants in the peppermint family (eg, mint, thyme, sage, rosemary, marjoram, basil, lavender) may experience allergic reactions with swelling, wheals, or erythema. Peppermint may also cause heartburn due to relaxation of the cardiac sphincter.

There is moderate-quality evidence for peppermint oil in the treatment of IBS.

Other symptoms may include nausea, vomiting, flushing, and headache.⁵⁸ The herb may also be both hepatotoxic and nephrotoxic at extremely high doses.⁵⁹ Other considerations for women are that it can trigger menstruation and should be avoided during pregnancy. Due to uncertain efficacy in this population, peppermint oil should not be used on the face of infants, young children, or pregnant women.^58,59

The bottom line

Peppermint appears to be safe and well-tolerated. It is useful in alleviating IBS symptoms and may be effective in the treatment of non-ulcerative dyspepsia, musculoskeletal pain, headache, and carpal tunnel syndrome.^54,55

Read part 2 here.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

The National Center for Complementary and Integrative Health, a division of the National Institutes of Medicine, estimates that about 38% of American adults use complementary and alternative medicine.¹ That statistic includes 17.7% who say they use natural products. Despite their popularity, many physicians remain skeptical—and for good reason. Enthusiasts frequently offer dramatic anecdotes to “prove” their supplements' worth, but little scientific support is available for most herbal remedies. There are, however, exceptions. As this review of the medical literature will reveal, there is evidence to support the use of capsaicin to relieve osteoarthritis (OA) and postherpetic neuralgia (PHN) and support for green tea to serve as a lipid-lowering agent and help treat diabetes. Similarly, researchers have found that peppermint may be of value in the management of irritable bowel syndrome (IBS). (We also review the literature on butterbur for migraine headaches, but serious safety issues exist; TABLE.)

In the second part of this series, which is available here, we explore what the evidence tells us about the use of turmeric, chamomile, rosemary, coffee, and cocoa.

Worth noting as you consider this—or any—review of herbals is that while there is limited scientific evidence to establish the safety and efficacy of most herbal products, they are nonetheless freely sold without US Food & Drug Administration (FDA) approval because under current regulations, they are considered dietary supplements. That legal designation means companies can manufacture, sell, and market herbs without first demonstrating safety and efficacy, as is required for pharmaceutical drugs. Because herbal medications do not require the same testing through the large randomized controlled trials (RCTs) required for pharmaceuticals, evidence is often based on smaller RCTs and other studies of lower overall quality. Despite these limitations, we believe it’s worth keeping an open mind about the value of evidence-based herbal and botanical treatments.

Overview

Capsaicin, an active compound in chili peppers, provokes a burning sensation, but also has a long history of use in pain treatment.² Qutenza, an FDA-approved chemically synthesized 8% capsaicin patch, is identical to the naturally occurring molecule.² Topically applied capsaicin exerts its therapeutic effect by rapidly depleting substance P, thus reducing the transmission of pain from C fibers to higher neurologic centers in the area of administration.³

Capsaicin provided mild to moderate efficacy in randomized trials for patients with hand and knee OA when compared with placebo.

Meta-analyses and systematic reviews have shown capsaicin is effective for various painful conditions, including peripheral diabetic neuropathy, OA, and PHN.

Peripheral neuropathy. A Cochrane review of 6 randomized, double-blind, placebo-controlled studies of at least 6 weeks' duration using topical 8% capsaicin to treat neuropathic pain concluded that high-concentration topical capsaicin used to treat PHN and human immunodeficiency virus (HIV)-associated neuropathy provided more relief in patients with high pain levels than control patients who received placebo, which was a subtherapeutic (0.04%) capsaicin cream. Number-needed-to-treat values were between 8 and 12. Local adverse events were common, but not consistently reported enough to calculate a number needed to harm.⁴

OA. Capsaicin provides mild to moderate efficacy in randomized trials for patients with hand and knee OA, when compared with placebo.^5-7 A systematic review of capsaicin for all osteoarthritic conditions noted that there was consistent evidence that capsaicin gel was effective for OA.⁸ However, a 2013 Cochrane review of only knee OA noted that capsicum extract did not provide significant clinical improvement for pain or function in knee OA and resulted in a significant number of adverse events.⁹

Low back pain (LBP). Based on a 2014 Cochrane review of 3 trials (755 subjects) of moderate quality, capsicum frutescens cream or plaster appeared more efficacious than placebo in people with chronic LBP.¹⁰ Based on current (low-quality) evidence in one trial, however, it’s not clear whether topical capsicum cream is more beneficial for acute LBP than a placebo.¹⁰

PHN. Topical 8% capsaicin is an FDA-approved treatment for PHN. A review and cost-effectiveness analysis demonstrated that 8% capsaicin had significantly higher effectiveness rates than the oral agents (tricyclic antidepressants, duloxetine, gabapentin, pregabalin) used to treat PHN.¹¹ In addition, the cost-effectiveness analysis found that the capsaicin patch was similar in cost to a topical lidocaine patch and oral products for PHN.¹¹

A meta-analysis of 7 RCTs indicated that 8% topical capsaicin was superior to the low-dose capsaicin patch for relieving pain associated with PHN.¹²

Adverse effects

Very few toxic effects have been reported during a half century of capsaicin use. Those that have been reported are mainly limited to mild local reactions.² The most common adverse effect of topical capsaicin is local irritation (burning, stinging, and erythema), which had been reported to occur in approximately 40% of patients.⁶ Nevertheless, more than 90% of the subjects in clinical studies were able to complete the studies, and pain rapidly resolved after patch removal.² Washing with soap and water may help prevent the compound from spreading to other parts of the body unintentionally.

The safety of the patch has been demonstrated with repeated dosing every 3 months for up to one year. However, the long-term risks of chronic capsaicin use and its effect on epidermal innervation are uncertain.⁵

The bottom line

Capsaicin appears to be an effective treatment for neuropathy and chronic LBP. It is FDA approved for the treatment of PHN. It may also benefit patients with OA and acute LBP. Serious adverse effects are uncommon with topical use. Common adverse effects include burning pain and irritation in the area of application, which can be intense and cause discontinuation.²

Overview

Petasites hybridus, also known as butterbur, is a member of the daisy family, Asteraceae, and is a perennial plant found throughout Europe and Asia.¹³ It was used as a remedy for ulcers, wounds, and inflammation in ancient Greece. Its calcium channel-blocking effects may counteract vasoconstriction and play a role in preventing hyper-excitation of neurons.¹⁴ Sesquiterpenes, the pharmacologically active compounds in butterbur, have strong anti-inflammatory and vasodilatory effects through lipoxygenase and leukotriene inhibition.¹⁴

Migraine headache. Butterbur appears to be effective in migraine prophylaxis. Several studies have shown butterbur to significantly reduce the number of migraine attacks per month when compared with placebo. In a small, randomized, placebo-controlled, parallel-group study on the efficacy and tolerability of a special butterbur root extract (Petadolex) for the prevention of migraine, response rate was 45% in the butterbur group vs 15% in the placebo group. Butterbur was well tolerated.¹⁵ Similar results were found in another RCT in which Petasites (butterbur) 75 mg bid significantly reduced migraine attack frequency by 48%, compared with 26% for the placebo group.¹⁶ Petadolex was well tolerated in this study, too, and no serious adverse events occurred. Findings suggest that 75 mg bid may be a good option for migraine prevention given the agent's safety profile.

Butterbur appears to be effective in migraine prophylaxis, but there are serious concerns about liver toxicity.

Petadolex may also be a good option in pediatric migraine. A 2005 study in children and adolescents found that 77% of patients experienced a reduction in attacks by at least 50% with butterbur. Patients were treated with 50 mg to 150 mg over 4 months.¹⁷

In their guidelines for migraine prevention, the American Academy of Neurology (AAN) and American Headache Society gave butterbur a Level A recommendation and concluded that butterbur should be offered to patients with migraine to reduce the frequency and severity of migraine attacks.¹⁸ However, the AAN has since changed its position, stating that “The 2012 AAN guideline, ‘Evidence-based guideline update: NSAIDS and other complementary treatments for episodic migraine prevention in adults’ has been retired by the AAN Board of Directors on September 16, 2015, due to serious safety concerns with a preventative treatment, butterbur, recommended by this guideline. The recommendations and conclusions in all retired guidelines are considered no longer valid and no longer supported by the AAN.”¹⁹

Allergic rhinitis. Although the data is not convincing, some studies have shown that butterbur may be beneficial for the treatment of allergic rhinitis.^20,21

Adverse effects

While the butterbur plant itself contains pyrrolizidine alkaloids (PA), which are hepatotoxic and carcinogenic, extracts of butterbur root that are almost completely free from these alkaloids are available. (Patients who choose to use butterbur should be advised to use only products that are certified and labeled pyrrolizidine alkaloids free.)

Petadolex, the medication used in migraine studies, was initially approved by the German health regulatory authority, but approval was later withdrawn due to concerns about liver toxicity.²² In 2012, the United Kingdom’s Medicines and Health Care Products Regulatory Agency withdrew all butterbur products from the market due to associated cases of liver toxicity.²² Petasites (butterbur) products are still available in the US market, and the risks and benefits should be discussed with all patients considering this treatment. Liver function monitoring is recommended for all patients using butterbur.²²

The herb can also cause dyspepsia, headache, itchy eyes, gastrointestinal symptoms, asthma, fatigue, and drowsiness. Additionally, people who are allergic to ragweed and daisies may have allergic reactions to butterbur. Eructation (belching) occurred in 7% of patients in a pediatric study.¹⁷

The bottom line

Butterbur appears to be efficacious for migraine prophylaxis, but long-term safety is unknown and serious concerns exist for liver toxicity.

Overview

Most tea leaves come from the Camellia sinensis bush, but green and black tea are processed differently to produce different end products.²³ It is estimated that green tea accounts for approximately a quarter of all tea consumption, and is most commonly consumed in Asian countries.²³ The health-promoting effects of green tea are mainly attributed to its polyphenol content.²⁴ While there are many types of tea due to how they are processed, green tea has the highest concentration of polyphenols, including catechins, which are powerful antioxidants.^23,24 Green tea has been used in traditional Chinese and Indian medicine to control bleeding, improve digestion, and promote overall health.²³

Dementia. Green tea polyphenols may enhance cognition and may protect against the development of dementia. In-vitro studies have shown that green tea reduces hydrogen peroxide and beta-amyloid peptides, which are significant in the development of Alzheimer’s disease.²⁵ A 12-subject double-blind study found green tea increased working memory and had an impact on frontoparietal brain connections.²⁶ Furthermore, a cohort study with 13,645 Japanese participants over a 5-year period found that frequent green tea consumption (>5 cups per day) was associated with a lower risk of dementa.²⁷ Additional studies are needed, but green tea may be useful in the treatment or prevention of dementia in the future.

Coronary artery disease. In one study, green tea plasma and urinary concentrations were associated with plasma biomarkers of cardiovascular disease and diabetes.²⁸ In one review, the consumption of green tea was associated with a statistically significant reduction in low-density lipoprotein cholesterol.²⁹ Furthermore, a 2015 systematic review and meta-analysis of prospective observational studies concluded that increased tea consumption (of any type) is associated with a reduced risk of coronary heart disease, cardiac death, stroke, and total mortality.³⁰

Cancer. Many studies have shown that green tea may reduce the risk of cancer development, although epidemiologic evidence is inconsistent. Studies have shown that cancer rates tend to be lower in those who consume higher levels of green tea.^31,32 Whether this can be attributed solely to green tea remains debatable. Several other studies have shown that polyphenols in green tea can inhibit the growth of cancer cells, but the exact mechanisms by which tea interacts with cancerous cells is unknown.²³

Many studies have shown that green tea may reduce the risk of cancer development, although epidemiologic evidence is inconsistent.

Several population-based studies have been performed, mostly in Japan, which showed green tea consumption reduced the risk of developing cancer. Fewer prostate cancer cases have been reported in men who consume green tea.³³ While studies have been performed to determine whether green tea has effects on pancreatic, esophageal, ovarian, breast, bladder, and colorectal cancer, the evidence remains inadequate.³²

Diabetes. Green tea has been shown in several studies to have a beneficial effect on diabetes. A retrospective Japanese cohort study showed that those who consumed green tea were one-third less likely to develop type 2 diabetes mellitus.³⁴ A 10-year study from Taiwan found lower body fat and smaller waist circumference in those who consumed green tea regularly.³⁵ A 2014 meta-analysis and systematic review of tea (any type) consumption and the risk of diabetes concluded that 3 cups or more of tea per day was associated with a lower risk of diabetes.³⁶ Another meta-analysis that included 17 RCTs and that focused on green tea concluded that green tea improves glucose control and A1C values.³⁷

Adverse effects

There have been concerns about potential hepatotoxicity induced by green tea intake.³⁸ However, a systematic review of 34 RCTs on liver-related adverse events from green tea showed only a slight elevation in liver function tests; no serious liver-related adverse events were reported.³⁸ This review suggested that liver-related adverse events after intake of green tea extracts are rare.³⁸

A meta-analysis that included 17 RCTs found that green tea improves glucose control and A1C values.

Consuming green tea in the diet may lower the risk of adverse effects since the concentration consumed is generally much lower than that found in extracts.

Contraindications to drinking green tea are few. Individuals with caffeine sensitivities could experience insomnia, anxiety, irritability, or upset stomach. Additionally, patients who are taking anticoagulation drugs, such as warfarin, should avoid green tea due to its vitamin K content, which can counter the effects of warfarin. Pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should use caution with green tea consumption.

The bottom line

Green tea consumption in the diet appears to be safe and may have beneficial effects on weight, diabetes mellitus risk, cancer risk, dementia, and cardiovascular risk. Patients may want to consider drinking green tea as part of a healthy diet, in combination with exercise.

Overview

Mentha piperita, also known as peppermint, is a hybrid between water mint and spearmint. It is found throughout Europe and North America and is commonly used in tea and toothpaste and as a flavoring for gum. It is used both orally and topically. Menthol and methyl salicylate are the main active ingredients in peppermint, and peppermint has calcium channel-blocker effects.³⁹ Menthol has been shown to help regulate cold and pain sensation through the TRPM8 receptor.⁴⁰ The peppermint herb has been studied in the treatment of multiple conditions.

IBS. It appears that peppermint inhibits spontaneous peristaltic activity, which reduces gastric emptying, decreases basal tone in the gastrointestinal tract, and slows down peristalsis in the gut.³⁹

The American College of Gastroenterology guidelines currently note that there is moderate-quality evidence for peppermint oil in the treatment of IBS.⁴¹ A Cochrane review concluded that peppermint appears to be beneficial for IBS-related symptoms and pain.⁴² In a systematic review of 9 studies from 2014, peppermint oil was found to be more effective than placebo for IBS symptoms such as pain, bloating, gas, and diarrhea.⁴³ The review also indicated that peppermint oil is safe, with heartburn being the most common complaint.⁴³ A 2016 study also found that triple-coated microspheres containing peppermint oil reduced the frequency and intensity of IBS symptoms.⁴⁴

Non-ulcer dyspepsia. In combination with caraway oil, peppermint oil can be used to reduce symptoms of non-ulcer dyspepsia.^45,46 A multicenter, randomized, placebo-controlled, double-blind study found that 43.3% of subjects improved with a peppermint-caraway oil combination after 8 weeks, compared with 3.5% receiving placebo.⁴⁶

Barium enema-related colonic spasm. Peppermint can relax the lower esophageal sphincter, and it has been shown to be useful as an antispasmodic agent for barium enema-related colonic spasm.^47,48

Itching/skin irritation. Peppermint, when applied topically, has been used to calm pruritus and relieve irritation and inflammation. It has a soothing and cooling effect on the skin. At least one study found it to be effective in the treatment of pruritus gravidarum, although the study population consisted of only 96 subjects.⁴⁹

Migraine headache. Initial small trials suggest that menthol is likely beneficial for migraine headaches. A pilot trial of 25 patients treated with topical menthol 6% gel for an acute migraine attack showed a significant improvement in headache intensity by 2 hours after gel application.⁵⁰ In a randomized, triple-blind, placebo-controlled, crossover study of 35 patients, a menthol 10% solution was shown to be more efficacious as abortive treatment of migraine headaches than placebo.⁵¹

Tension headache. A randomized, placebo-controlled double-blind crossover study of topical peppermint oil showed a significant clinical reduction in tension headache pain.⁵² Another small randomized, double-blind trial showed that tiger balm (containing menthol as the main ingredient) also produced statistically significant improvement in tension headache discomfort compared with placebo.⁵³

Musculoskeletal pain. A small study comparing topical menthol to ice for muscle soreness noted decreased perceived discomfort with menthol.⁵⁴ Menthol has also been shown to reduce pain in patients with knee OA.⁵⁵

Carpal tunnel syndrome (CTS). A triple-blind, randomized, placebo-controlled trial concluded that topical menthol acutely reduced pain intensity during the working day in slaughterhouse workers with CTS and should be considered as an effective non-systemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.⁵⁶

Adverse effects

Peppermint appears to be safe for most adults when used in small doses, and serious adverse effects are rare.^43,57 While peppermint tea appears to be safe in moderate to large amounts, people allergic to plants in the peppermint family (eg, mint, thyme, sage, rosemary, marjoram, basil, lavender) may experience allergic reactions with swelling, wheals, or erythema. Peppermint may also cause heartburn due to relaxation of the cardiac sphincter.

There is moderate-quality evidence for peppermint oil in the treatment of IBS.

Other symptoms may include nausea, vomiting, flushing, and headache.⁵⁸ The herb may also be both hepatotoxic and nephrotoxic at extremely high doses.⁵⁹ Other considerations for women are that it can trigger menstruation and should be avoided during pregnancy. Due to uncertain efficacy in this population, peppermint oil should not be used on the face of infants, young children, or pregnant women.^58,59

The bottom line

Peppermint appears to be safe and well-tolerated. It is useful in alleviating IBS symptoms and may be effective in the treatment of non-ulcerative dyspepsia, musculoskeletal pain, headache, and carpal tunnel syndrome.^54,55

Read part 2 here.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

The National Center for Complementary and Integrative Health, a division of the National Institutes of Medicine, estimates that about 38% of American adults use complementary and alternative medicine.¹ That statistic includes 17.7% who say they use natural products. Despite their popularity, many physicians remain skeptical—and for good reason. Enthusiasts frequently offer dramatic anecdotes to “prove” their supplements' worth, but little scientific support is available for most herbal remedies. There are, however, exceptions. As this review of the medical literature will reveal, there is evidence to support the use of capsaicin to relieve osteoarthritis (OA) and postherpetic neuralgia (PHN) and support for green tea to serve as a lipid-lowering agent and help treat diabetes. Similarly, researchers have found that peppermint may be of value in the management of irritable bowel syndrome (IBS). (We also review the literature on butterbur for migraine headaches, but serious safety issues exist; TABLE.)

In the second part of this series, which is available here, we explore what the evidence tells us about the use of turmeric, chamomile, rosemary, coffee, and cocoa.

Worth noting as you consider this—or any—review of herbals is that while there is limited scientific evidence to establish the safety and efficacy of most herbal products, they are nonetheless freely sold without US Food & Drug Administration (FDA) approval because under current regulations, they are considered dietary supplements. That legal designation means companies can manufacture, sell, and market herbs without first demonstrating safety and efficacy, as is required for pharmaceutical drugs. Because herbal medications do not require the same testing through the large randomized controlled trials (RCTs) required for pharmaceuticals, evidence is often based on smaller RCTs and other studies of lower overall quality. Despite these limitations, we believe it’s worth keeping an open mind about the value of evidence-based herbal and botanical treatments.

Overview

Capsaicin, an active compound in chili peppers, provokes a burning sensation, but also has a long history of use in pain treatment.² Qutenza, an FDA-approved chemically synthesized 8% capsaicin patch, is identical to the naturally occurring molecule.² Topically applied capsaicin exerts its therapeutic effect by rapidly depleting substance P, thus reducing the transmission of pain from C fibers to higher neurologic centers in the area of administration.³

Capsaicin provided mild to moderate efficacy in randomized trials for patients with hand and knee OA when compared with placebo.

Meta-analyses and systematic reviews have shown capsaicin is effective for various painful conditions, including peripheral diabetic neuropathy, OA, and PHN.

Peripheral neuropathy. A Cochrane review of 6 randomized, double-blind, placebo-controlled studies of at least 6 weeks' duration using topical 8% capsaicin to treat neuropathic pain concluded that high-concentration topical capsaicin used to treat PHN and human immunodeficiency virus (HIV)-associated neuropathy provided more relief in patients with high pain levels than control patients who received placebo, which was a subtherapeutic (0.04%) capsaicin cream. Number-needed-to-treat values were between 8 and 12. Local adverse events were common, but not consistently reported enough to calculate a number needed to harm.⁴

OA. Capsaicin provides mild to moderate efficacy in randomized trials for patients with hand and knee OA, when compared with placebo.^5-7 A systematic review of capsaicin for all osteoarthritic conditions noted that there was consistent evidence that capsaicin gel was effective for OA.⁸ However, a 2013 Cochrane review of only knee OA noted that capsicum extract did not provide significant clinical improvement for pain or function in knee OA and resulted in a significant number of adverse events.⁹

Low back pain (LBP). Based on a 2014 Cochrane review of 3 trials (755 subjects) of moderate quality, capsicum frutescens cream or plaster appeared more efficacious than placebo in people with chronic LBP.¹⁰ Based on current (low-quality) evidence in one trial, however, it’s not clear whether topical capsicum cream is more beneficial for acute LBP than a placebo.¹⁰

PHN. Topical 8% capsaicin is an FDA-approved treatment for PHN. A review and cost-effectiveness analysis demonstrated that 8% capsaicin had significantly higher effectiveness rates than the oral agents (tricyclic antidepressants, duloxetine, gabapentin, pregabalin) used to treat PHN.¹¹ In addition, the cost-effectiveness analysis found that the capsaicin patch was similar in cost to a topical lidocaine patch and oral products for PHN.¹¹

A meta-analysis of 7 RCTs indicated that 8% topical capsaicin was superior to the low-dose capsaicin patch for relieving pain associated with PHN.¹²

Adverse effects

Very few toxic effects have been reported during a half century of capsaicin use. Those that have been reported are mainly limited to mild local reactions.² The most common adverse effect of topical capsaicin is local irritation (burning, stinging, and erythema), which had been reported to occur in approximately 40% of patients.⁶ Nevertheless, more than 90% of the subjects in clinical studies were able to complete the studies, and pain rapidly resolved after patch removal.² Washing with soap and water may help prevent the compound from spreading to other parts of the body unintentionally.

The safety of the patch has been demonstrated with repeated dosing every 3 months for up to one year. However, the long-term risks of chronic capsaicin use and its effect on epidermal innervation are uncertain.⁵

The bottom line

Capsaicin appears to be an effective treatment for neuropathy and chronic LBP. It is FDA approved for the treatment of PHN. It may also benefit patients with OA and acute LBP. Serious adverse effects are uncommon with topical use. Common adverse effects include burning pain and irritation in the area of application, which can be intense and cause discontinuation.²

Overview

Petasites hybridus, also known as butterbur, is a member of the daisy family, Asteraceae, and is a perennial plant found throughout Europe and Asia.¹³ It was used as a remedy for ulcers, wounds, and inflammation in ancient Greece. Its calcium channel-blocking effects may counteract vasoconstriction and play a role in preventing hyper-excitation of neurons.¹⁴ Sesquiterpenes, the pharmacologically active compounds in butterbur, have strong anti-inflammatory and vasodilatory effects through lipoxygenase and leukotriene inhibition.¹⁴

Migraine headache. Butterbur appears to be effective in migraine prophylaxis. Several studies have shown butterbur to significantly reduce the number of migraine attacks per month when compared with placebo. In a small, randomized, placebo-controlled, parallel-group study on the efficacy and tolerability of a special butterbur root extract (Petadolex) for the prevention of migraine, response rate was 45% in the butterbur group vs 15% in the placebo group. Butterbur was well tolerated.¹⁵ Similar results were found in another RCT in which Petasites (butterbur) 75 mg bid significantly reduced migraine attack frequency by 48%, compared with 26% for the placebo group.¹⁶ Petadolex was well tolerated in this study, too, and no serious adverse events occurred. Findings suggest that 75 mg bid may be a good option for migraine prevention given the agent's safety profile.

Butterbur appears to be effective in migraine prophylaxis, but there are serious concerns about liver toxicity.

Petadolex may also be a good option in pediatric migraine. A 2005 study in children and adolescents found that 77% of patients experienced a reduction in attacks by at least 50% with butterbur. Patients were treated with 50 mg to 150 mg over 4 months.¹⁷

In their guidelines for migraine prevention, the American Academy of Neurology (AAN) and American Headache Society gave butterbur a Level A recommendation and concluded that butterbur should be offered to patients with migraine to reduce the frequency and severity of migraine attacks.¹⁸ However, the AAN has since changed its position, stating that “The 2012 AAN guideline, ‘Evidence-based guideline update: NSAIDS and other complementary treatments for episodic migraine prevention in adults’ has been retired by the AAN Board of Directors on September 16, 2015, due to serious safety concerns with a preventative treatment, butterbur, recommended by this guideline. The recommendations and conclusions in all retired guidelines are considered no longer valid and no longer supported by the AAN.”¹⁹

Allergic rhinitis. Although the data is not convincing, some studies have shown that butterbur may be beneficial for the treatment of allergic rhinitis.^20,21

Adverse effects

While the butterbur plant itself contains pyrrolizidine alkaloids (PA), which are hepatotoxic and carcinogenic, extracts of butterbur root that are almost completely free from these alkaloids are available. (Patients who choose to use butterbur should be advised to use only products that are certified and labeled pyrrolizidine alkaloids free.)

Petadolex, the medication used in migraine studies, was initially approved by the German health regulatory authority, but approval was later withdrawn due to concerns about liver toxicity.²² In 2012, the United Kingdom’s Medicines and Health Care Products Regulatory Agency withdrew all butterbur products from the market due to associated cases of liver toxicity.²² Petasites (butterbur) products are still available in the US market, and the risks and benefits should be discussed with all patients considering this treatment. Liver function monitoring is recommended for all patients using butterbur.²²

The herb can also cause dyspepsia, headache, itchy eyes, gastrointestinal symptoms, asthma, fatigue, and drowsiness. Additionally, people who are allergic to ragweed and daisies may have allergic reactions to butterbur. Eructation (belching) occurred in 7% of patients in a pediatric study.¹⁷

The bottom line

Butterbur appears to be efficacious for migraine prophylaxis, but long-term safety is unknown and serious concerns exist for liver toxicity.

Overview

Most tea leaves come from the Camellia sinensis bush, but green and black tea are processed differently to produce different end products.²³ It is estimated that green tea accounts for approximately a quarter of all tea consumption, and is most commonly consumed in Asian countries.²³ The health-promoting effects of green tea are mainly attributed to its polyphenol content.²⁴ While there are many types of tea due to how they are processed, green tea has the highest concentration of polyphenols, including catechins, which are powerful antioxidants.^23,24 Green tea has been used in traditional Chinese and Indian medicine to control bleeding, improve digestion, and promote overall health.²³

Dementia. Green tea polyphenols may enhance cognition and may protect against the development of dementia. In-vitro studies have shown that green tea reduces hydrogen peroxide and beta-amyloid peptides, which are significant in the development of Alzheimer’s disease.²⁵ A 12-subject double-blind study found green tea increased working memory and had an impact on frontoparietal brain connections.²⁶ Furthermore, a cohort study with 13,645 Japanese participants over a 5-year period found that frequent green tea consumption (>5 cups per day) was associated with a lower risk of dementa.²⁷ Additional studies are needed, but green tea may be useful in the treatment or prevention of dementia in the future.

Coronary artery disease. In one study, green tea plasma and urinary concentrations were associated with plasma biomarkers of cardiovascular disease and diabetes.²⁸ In one review, the consumption of green tea was associated with a statistically significant reduction in low-density lipoprotein cholesterol.²⁹ Furthermore, a 2015 systematic review and meta-analysis of prospective observational studies concluded that increased tea consumption (of any type) is associated with a reduced risk of coronary heart disease, cardiac death, stroke, and total mortality.³⁰

Cancer. Many studies have shown that green tea may reduce the risk of cancer development, although epidemiologic evidence is inconsistent. Studies have shown that cancer rates tend to be lower in those who consume higher levels of green tea.^31,32 Whether this can be attributed solely to green tea remains debatable. Several other studies have shown that polyphenols in green tea can inhibit the growth of cancer cells, but the exact mechanisms by which tea interacts with cancerous cells is unknown.²³

Many studies have shown that green tea may reduce the risk of cancer development, although epidemiologic evidence is inconsistent.

Several population-based studies have been performed, mostly in Japan, which showed green tea consumption reduced the risk of developing cancer. Fewer prostate cancer cases have been reported in men who consume green tea.³³ While studies have been performed to determine whether green tea has effects on pancreatic, esophageal, ovarian, breast, bladder, and colorectal cancer, the evidence remains inadequate.³²

Diabetes. Green tea has been shown in several studies to have a beneficial effect on diabetes. A retrospective Japanese cohort study showed that those who consumed green tea were one-third less likely to develop type 2 diabetes mellitus.³⁴ A 10-year study from Taiwan found lower body fat and smaller waist circumference in those who consumed green tea regularly.³⁵ A 2014 meta-analysis and systematic review of tea (any type) consumption and the risk of diabetes concluded that 3 cups or more of tea per day was associated with a lower risk of diabetes.³⁶ Another meta-analysis that included 17 RCTs and that focused on green tea concluded that green tea improves glucose control and A1C values.³⁷

Adverse effects

There have been concerns about potential hepatotoxicity induced by green tea intake.³⁸ However, a systematic review of 34 RCTs on liver-related adverse events from green tea showed only a slight elevation in liver function tests; no serious liver-related adverse events were reported.³⁸ This review suggested that liver-related adverse events after intake of green tea extracts are rare.³⁸

A meta-analysis that included 17 RCTs found that green tea improves glucose control and A1C values.

Consuming green tea in the diet may lower the risk of adverse effects since the concentration consumed is generally much lower than that found in extracts.

Contraindications to drinking green tea are few. Individuals with caffeine sensitivities could experience insomnia, anxiety, irritability, or upset stomach. Additionally, patients who are taking anticoagulation drugs, such as warfarin, should avoid green tea due to its vitamin K content, which can counter the effects of warfarin. Pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should use caution with green tea consumption.

The bottom line

Green tea consumption in the diet appears to be safe and may have beneficial effects on weight, diabetes mellitus risk, cancer risk, dementia, and cardiovascular risk. Patients may want to consider drinking green tea as part of a healthy diet, in combination with exercise.

Overview

Mentha piperita, also known as peppermint, is a hybrid between water mint and spearmint. It is found throughout Europe and North America and is commonly used in tea and toothpaste and as a flavoring for gum. It is used both orally and topically. Menthol and methyl salicylate are the main active ingredients in peppermint, and peppermint has calcium channel-blocker effects.³⁹ Menthol has been shown to help regulate cold and pain sensation through the TRPM8 receptor.⁴⁰ The peppermint herb has been studied in the treatment of multiple conditions.

IBS. It appears that peppermint inhibits spontaneous peristaltic activity, which reduces gastric emptying, decreases basal tone in the gastrointestinal tract, and slows down peristalsis in the gut.³⁹

The American College of Gastroenterology guidelines currently note that there is moderate-quality evidence for peppermint oil in the treatment of IBS.⁴¹ A Cochrane review concluded that peppermint appears to be beneficial for IBS-related symptoms and pain.⁴² In a systematic review of 9 studies from 2014, peppermint oil was found to be more effective than placebo for IBS symptoms such as pain, bloating, gas, and diarrhea.⁴³ The review also indicated that peppermint oil is safe, with heartburn being the most common complaint.⁴³ A 2016 study also found that triple-coated microspheres containing peppermint oil reduced the frequency and intensity of IBS symptoms.⁴⁴

Non-ulcer dyspepsia. In combination with caraway oil, peppermint oil can be used to reduce symptoms of non-ulcer dyspepsia.^45,46 A multicenter, randomized, placebo-controlled, double-blind study found that 43.3% of subjects improved with a peppermint-caraway oil combination after 8 weeks, compared with 3.5% receiving placebo.⁴⁶

Barium enema-related colonic spasm. Peppermint can relax the lower esophageal sphincter, and it has been shown to be useful as an antispasmodic agent for barium enema-related colonic spasm.^47,48

Itching/skin irritation. Peppermint, when applied topically, has been used to calm pruritus and relieve irritation and inflammation. It has a soothing and cooling effect on the skin. At least one study found it to be effective in the treatment of pruritus gravidarum, although the study population consisted of only 96 subjects.⁴⁹

Migraine headache. Initial small trials suggest that menthol is likely beneficial for migraine headaches. A pilot trial of 25 patients treated with topical menthol 6% gel for an acute migraine attack showed a significant improvement in headache intensity by 2 hours after gel application.⁵⁰ In a randomized, triple-blind, placebo-controlled, crossover study of 35 patients, a menthol 10% solution was shown to be more efficacious as abortive treatment of migraine headaches than placebo.⁵¹

Tension headache. A randomized, placebo-controlled double-blind crossover study of topical peppermint oil showed a significant clinical reduction in tension headache pain.⁵² Another small randomized, double-blind trial showed that tiger balm (containing menthol as the main ingredient) also produced statistically significant improvement in tension headache discomfort compared with placebo.⁵³

Musculoskeletal pain. A small study comparing topical menthol to ice for muscle soreness noted decreased perceived discomfort with menthol.⁵⁴ Menthol has also been shown to reduce pain in patients with knee OA.⁵⁵

Carpal tunnel syndrome (CTS). A triple-blind, randomized, placebo-controlled trial concluded that topical menthol acutely reduced pain intensity during the working day in slaughterhouse workers with CTS and should be considered as an effective non-systemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.⁵⁶

Adverse effects

Peppermint appears to be safe for most adults when used in small doses, and serious adverse effects are rare.^43,57 While peppermint tea appears to be safe in moderate to large amounts, people allergic to plants in the peppermint family (eg, mint, thyme, sage, rosemary, marjoram, basil, lavender) may experience allergic reactions with swelling, wheals, or erythema. Peppermint may also cause heartburn due to relaxation of the cardiac sphincter.

There is moderate-quality evidence for peppermint oil in the treatment of IBS.

Other symptoms may include nausea, vomiting, flushing, and headache.⁵⁸ The herb may also be both hepatotoxic and nephrotoxic at extremely high doses.⁵⁹ Other considerations for women are that it can trigger menstruation and should be avoided during pregnancy. Due to uncertain efficacy in this population, peppermint oil should not be used on the face of infants, young children, or pregnant women.^58,59

The bottom line

Peppermint appears to be safe and well-tolerated. It is useful in alleviating IBS symptoms and may be effective in the treatment of non-ulcerative dyspepsia, musculoskeletal pain, headache, and carpal tunnel syndrome.^54,55

Read part 2 here.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.

Overview

Chamomile, a member of the Asteraceae/Compositae family, is one of the oldest herbal medicines. It has been used for hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations have been developed, the most popular being herbal tea.²⁴

A controlled clinical trial of chamomile extract suggested that it may have modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Individuals with a hypersensitivity to plants of the Asteraceae (Compositae) family such as ragweed (Ambrosia spp.), marigold flower (Calendula officinalis), and chrysanthemum (Chrysanthemum spp.) may show a similar reaction to chamomile.²⁵

Anxiety. A controlled clinical trial of chamomile extract for generalized anxiety disorder (GAD) suggested that it may have modest anxiolytic activity in patients with mild to moderate GAD.²⁶ Another randomized, double-blind, placebo-controlled trial found oral chamomile extract was efficacious and well-tolerated in patients experiencing mild to moderate GAD and may provide an alternative therapeutic anxiolytic for patients with mild GAD.²⁵ In addition to its anxiolytic activity, chamomile may also provide clinically meaningful antidepressant activity.²⁶

Insomnia. Chamomile may have some impact on sleep diary measures (total sleep time, sleep efficiency, sleep latency, wake after sleep onset, sleep quality, and number of awakenings) relative to placebo in adults with chronic primary insomnia, according to a small randomized, double-blind, placebo-controlled pilot trial involving 34 patients.²⁷ However, a systematic review found no statistically significant difference between any herbal medicine (including chamomile) and placebo, for clinical efficacy in patients with insomnia. A similar, or smaller, number of adverse events per person were reported with chamomile compared with placebo, suggesting safe use.²⁸

Infantile colic. A small prospective double-blind study on the use of chamomile-containing tea on infantile colic showed statistically significant symptom improvement in tea-treated infants. The study did note, however, that prolonged ingestion of herbal teas may lead to decreased milk intake.^29,30

Adverse effects

As noted earlier, a systematic review found that the number of adverse events per person reported with chamomile was comparable to the number associated with placebo, suggesting that it is safe.²⁸

The bottom line

Chamomile appears to be safe with minimal adverse effects and may be effective for the treatment of anxiety, insomnia, and infantile colic.

Rosemary

Overview

Rosemary, officially known as Rosmarinus officinalis, is a medicinal evergreen plant native to the Mediterranean area that appears to increase microcapillary perfusion.³¹

Topical rosemary oil may be useful in the treatment of alopecia, with minimal adverse effects.

Alopecia. A randomized double-blind controlled trial found that essential oils including rosemary oil (as well as thyme, lavender, and cedarwood) massaged into the scalp improved hair growth in almost half of patients with alopecia areata after 7 months.³² Another randomized trial comparing rosemary oil to minoxidil 2% for androgenetic alopecia showed a significant increase in hair count at the 6-month endpoint compared with the baseline, but no significant difference was found between the study groups regarding hair count either at Month 3 or Month 6 (P >.05). ³¹

Adverse effects

In the randomized trial described above comparing rosemary oil to minoxidil 2%, adverse effects appeared to be rare for topical rosemary oil. Scalp itching was more frequent in the minoxidil group.³¹

The bottom line

Topical rosemary oil may be useful in the treatment of alopecia with minimal adverse effects.

Overview

Coffee is one of the most widely used botanicals with approximately 3.5 billion cups of coffee consumed per day worldwide. It is a popular beverage because of its unique aromatic taste and its use as a central nervous system stimulant. The coffee tree (genus coffea) is found throughout Latin America, Africa, and eastern Asia. Two of the most common commercially grown species are Coffea arabica (Arabicas) and Coffea canephora (Robusta). Processing and roasting methods may differ and produce variations in flavor and aroma. The degree of roasting also affects the caffeine content.

Coffee consumption leads to increased alertness and can boost mental performance. Based on the literature and US Food and Drug Administration recommendations, four 8-oz cups of coffee (about 400 mg of caffeine) daily is an acceptable average amount of caffeine. More than 500 mg/d is considered excessive use of coffee.^33,34

Overall mortality. A 2008 study showed that regular coffee was not associated with increased or decreased mortality in both men and women.³⁵ However, more recent studies show an inverse relationship between mortality and coffee consumption.

Specifically, a 2014 meta-analysis found an inverse relationship between coffee and mortality.³⁶ A large prospective cohort study from 2015 that included 79,234 women and 76,704 men found that drinking coffee was inversely associated with overall mortality.³⁷ In this cohort study, an inverse association were observed for deaths from heart disease, respiratory disease, diabetes, and self-harm.³⁷ While mechanisms were not analyzed, coffee may reduce mortality risk by affecting inflammation, lung function, insulin sensitivity, and depression.

Cardiovascular disease. Coffee consumption may modestly reduce the risk of stroke, according to a prospective cohort study of 83,076 women from the Nurses’ Health Study who were followed for 24 years.³⁸ Reduced cardiovascular mortality was also found in a large prospective cohort study, as noted in the mortality discussion above.³⁷ A 2014 meta-analysis concluded that coffee consumption is inversely associated with cardiovascular mortality. Drinking 3 or 4 cups a day appears to be the amount that may decrease one’s risk of death when compared to those who do not drink coffee at all.³⁶

Liver disease. Friedrich et al performed a study involving 379 patients with end stage liver disease, and found that coffee consumption delayed the progression of disease in patients with both alcoholic liver disease and primary sclerosing cholangitis.³⁹ Coffee consumption also increased long-term survival after liver transplantation.³⁹ However, the study found that coffee did not have any effect on patients with chronic viral hepatitis.

In a 2016 meta-analysis, caffeinated coffee consumption reduced hepatic fibrosis of nonalcoholic fatty liver disease, although caffeine consumption did not reduce the prevalence of nonalcoholic fatty liver disease.⁴⁰ Another meta-analysis, including 16 studies, also found caffeine reduced the risk for hepatic fibrosis and cirrhosis.⁴¹

Depression. Based on 2 different systematic reviews and meta-analyses from 2016, coffee consumption appears to have a significant protective effect, decreasing the risk of developing depression.^40,42

Alzheimer’s disease/dementia. Coffee, tea, and caffeine consumption show promise in reducing the risk of cognitive decline and dementia. Individuals who consume one to 2 cups of coffee per day had a decreased incidence of mild cognitive impairment compared to non-drinkers.⁴³ A 2015 Japanese study also found an inverse association between coffee consumption and dementia among women, nonsmokers, and those who do not drink alcohol.⁴⁴ Most recently, a 2016 study, the Women’s Health Initiative Memory Study, looked at incident dementia rates in women >65 years of age with high vs low caffeine intake. Women with higher caffeine intake were less likely to develop dementia or any cognitive impairment compared with those consuming <64 mg/day.⁴⁵

Type 2 diabetes. A 2009 prospective cohort study, which included 40,011 participants followed for more than 10 years, found that drinking at least 3 cups of coffee or tea was associated with a lowered risk of type 2 diabetes.⁴⁶ A 2009 systematic review of 20 cohort studies showed that high intakes of coffee, decaffeinated coffee, and tea are associated with a reduced risk of diabetes.⁴⁷

A meta-analysis of 12 studies involving 832,956 participants found an inverse relationship between cutaneous melanoma and coffee consumption.

Melanoma. A meta-analysis of 12 studies involving 832,956 participants demon­strated an inverse relationship between cutaneous melanoma and coffee consumption.⁴⁷ The risk of melanoma decreased by 3% and 4% for one cup/day of total coffee and caffeinated coffee consumption, respectively. Furthermore, a 2016 meta-analysis found that caffeinated coffee may have greater chemopreventive effects against melanoma than decaffeinated coffee.⁴⁸

Adverse effects

Despite the many potential benefits of coffee, caffeine is a potent drug that should be used with caution.⁴⁹ People with underlying heart problems should avoid caffeine due to concern that it may cause palpitations from tachycardia. It may worsen anxiety problems or depression. Coffee may increase the production of stomach acids, which can worsen acid reflux or stomach ulcers.

Regular coffee intake is associated with a lower risk of mortality, reduced CV events, and a reduction in liver disease progression.

Caffeine is a potent diuretic and may decrease absorption of calcium and cause OA. Caffeine may cause dependence and withdrawal symptoms. Some of the symptoms of withdrawal include drowsiness, headaches, irritability, nausea, and vomiting. It may disrupt sleeping patterns by causing jitters and sleeplessness.⁴⁹ Additionally, large amounts of caffeine may cause overdose and death.

The bottom line

Regular coffee intake is associated with a lower risk of mortality, reduced cardiovascular events, and a reduction in liver disease progression. Coffee may also have some utility for improving cognitive function and reducing the risk of type 2 diabetes. Caffeinated coffee should be limited to no more than 32 oz per day, due to the risk of insomnia, palpitations, anxiety, and gastritis.

Overview

Few natural products have been claimed to successfully treat as many disorders as chocolate. The modern concept of chocolate as food has overshadowed its traditional medicinal use, although recent trials have looked at evidence for some of its traditional uses. Chocolate is processed from the pod of the cacao plant. The earliest evidence for its medical use is in Mayan civilizations, and for most of its approximately 4000-year history, chocolate was consumed as a bitter drink referred to as the “drink of the Gods.” The traditional drink was mixed with water, vanilla, honey, chili peppers, and other spices. Important components in chocolate include flavonoids (antioxidants), cocoa butter, caffeine, theobromine, and phenylethylamine.  

Chocolate has stimulating, anti-inflammatory, neuroprotective, and cardioprotective effects, and improves the bioavailability of nitric oxide, which can improve blood pressure and platelet function.⁵⁰ Epicatechin (an antioxidant) in cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated by the anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-kappaB.⁵¹

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.

Dark chocolate appears to have the greatest benefit, as milk binds to antioxidants in chocolate, making them unavailable. Therefore, milk chocolate is not a good antioxidant source. There is no specific amount of chocolate that is known to be ideal, but an average of one to 2 ounces per day is often used in studies.

Cardiovascular effects. Chocolate does contain saturated fat, but a comparative, double-blind study found that short-term use of cocoa powder lowered plasma low-density lipoprotein (LDL) cholesterol, oxidized LDL, and apo B concentrations, and the plasma high-density lipoprotein (HDL) cholesterol concentration increased, relative to baseline in the low-, middle-, and high-cocoa groups.⁵² A small randomized crossover trial without clinical outcomes indicated that chocolate may increase HDL cholesterol without increasing weight.⁵³

A meta-analysis of short-term (2-12 weeks) treatment with dark chocolate/cocoa products showed reductions in LDL and total cholesterol, but no changes in HDL or triglycerides.⁵⁴ Another meta-analysis of RCTs, however, showed no short-term effect of cocoa/chocolate on lipid concentrations.⁵⁵ A randomized, placebo-controlled double-blind study of 62 patients with diabetes and hypertension showed that high polyphenol chocolate improved triglyceride levels.⁵⁶

Chocolate intake was associated with a lower risk of cognitive decline, with the greatest benefit noted in those who averaged more than one chocolate bar per week.

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.^57-59 A best case scenario analysis using a Markov model to predict the long-term effectiveness and cost effectiveness of daily dark chocolate consumption in a population with metabolic syndrome at high risk of cardiovascular disease concluded that daily consumption of dark chocolate can reduce cardiovascular events by 85 per 10,000 population treated over 10 years. The study concluded that $42 could be cost effectively spent per person per year on prevention strategies using dark chocolate.⁵⁹

In addition, a meta-analysis of 7 observational studies showed that high levels of chocolate consumption (any type) were associated with a 29% reduction in stroke compared with the lowest levels of chocolate intake.⁵⁷ Results of a similar meta-analysis from Neurology in 2012 also suggested that moderate chocolate consumption (any type) may lower the risk of stroke.⁶⁰

That said, 2 systematic reviews specifically relating to the risk of coronary heart disease and chocolate intake were inconclusive.^61-62

Blood pressure (BP). An RCT published in JAMA indicates that inclusion of small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced BP and improved the formation of vasodilative nitric oxide.⁶³ A meta-analysis of 10 RCTs also showed mean BP change in the active cocoa treatment arms across all trials was -4.5 mm Hg (95% confidence interval (CI), -5.9 to -3.2; P<.001) for systolic BP and -2.5 mm Hg (95% CI, -3.9 to -1.2; P<.001) for diastolic BP.⁶⁴

A Cochrane Review meta-analysis of 20 studies revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products compared with control in short-term trials of 2 to 18 weeks' duration.⁶⁵ Because studies have shown improvement in BP with chocolate intake, investigations into a role of chocolate in the prevention of preeclampsia have been undertaken. In some studies, chocolate intake was associated with reduced odds of preeclampsia and gestational hypertension.^66,67

Diabetes. Chocolate may exert significant vascular protection because of its antioxidant properties and possible increase of nitric oxide bioavailability, which can influence glucose uptake. A small trial comparing the effects of either dark or white chocolate bars (which do not contain the polyphenols) showed improved BP and glucose and insulin responses to an oral glucose tolerance test in healthy subjects on dark chocolate, but not white chocolate.⁶⁸ A comparison of chocolate consumption and risk of diabetes in the Physicians’ Health Study showed an inverse relationship between chocolate intake with incident disease, but this association appeared only to apply in younger and normal-body weight men after controlling for comprehensive lifestyles, including total energy consumption.⁶⁹

Fatigue. The effect of chocolate on a person’s energy level has been noted for centuries.⁷⁰ A small randomized trial showed improved energy levels in those treated with higher chocolate intakes. In a double-blind, randomized, clinical pilot crossover study, high cocoa liquor/polyphenol rich chocolate, reduced fatigue in subjects with chronic fatigue syndrome.⁷¹

Anxiety. A small randomized trial showed chocolate decreased anxiety in high-anxiety trait subjects and improved the anxiety level and the energy levels of low-anxiety trait participants.⁷²

Eye effects. The literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension. However, a meta-analysis showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension, and appear to play a part in both improving and slowing the progression of visual field loss.⁷³

Cognitive decline. Chocolate intake (any type) was associated with a lower risk of cognitive decline (RR = 0.59; 95% CI, 0.38-0.92) with the greatest benefit noted in those who averaged more than one chocolate bar or one tablespoon of cocoa powder per week. This protective effect was observed only among subjects with an average daily consumption of caffeine <75  mg (69% of the participants; RR = 0.50; 95% CI, 0.31-0.82).⁷⁴

The bottom line

Chocolate with high cocoa content (dark chocolate) appears to be safe and beneficial as part of a healthy diet and lifestyle that includes exercise and stress reduction to decrease cardiovascular risk and may improve energy levels.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.

Overview

Chamomile, a member of the Asteraceae/Compositae family, is one of the oldest herbal medicines. It has been used for hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations have been developed, the most popular being herbal tea.²⁴

A controlled clinical trial of chamomile extract suggested that it may have modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Individuals with a hypersensitivity to plants of the Asteraceae (Compositae) family such as ragweed (Ambrosia spp.), marigold flower (Calendula officinalis), and chrysanthemum (Chrysanthemum spp.) may show a similar reaction to chamomile.²⁵

Anxiety. A controlled clinical trial of chamomile extract for generalized anxiety disorder (GAD) suggested that it may have modest anxiolytic activity in patients with mild to moderate GAD.²⁶ Another randomized, double-blind, placebo-controlled trial found oral chamomile extract was efficacious and well-tolerated in patients experiencing mild to moderate GAD and may provide an alternative therapeutic anxiolytic for patients with mild GAD.²⁵ In addition to its anxiolytic activity, chamomile may also provide clinically meaningful antidepressant activity.²⁶

Insomnia. Chamomile may have some impact on sleep diary measures (total sleep time, sleep efficiency, sleep latency, wake after sleep onset, sleep quality, and number of awakenings) relative to placebo in adults with chronic primary insomnia, according to a small randomized, double-blind, placebo-controlled pilot trial involving 34 patients.²⁷ However, a systematic review found no statistically significant difference between any herbal medicine (including chamomile) and placebo, for clinical efficacy in patients with insomnia. A similar, or smaller, number of adverse events per person were reported with chamomile compared with placebo, suggesting safe use.²⁸

Infantile colic. A small prospective double-blind study on the use of chamomile-containing tea on infantile colic showed statistically significant symptom improvement in tea-treated infants. The study did note, however, that prolonged ingestion of herbal teas may lead to decreased milk intake.^29,30

Adverse effects

As noted earlier, a systematic review found that the number of adverse events per person reported with chamomile was comparable to the number associated with placebo, suggesting that it is safe.²⁸

The bottom line

Chamomile appears to be safe with minimal adverse effects and may be effective for the treatment of anxiety, insomnia, and infantile colic.

Rosemary

Overview

Rosemary, officially known as Rosmarinus officinalis, is a medicinal evergreen plant native to the Mediterranean area that appears to increase microcapillary perfusion.³¹

Topical rosemary oil may be useful in the treatment of alopecia, with minimal adverse effects.

Alopecia. A randomized double-blind controlled trial found that essential oils including rosemary oil (as well as thyme, lavender, and cedarwood) massaged into the scalp improved hair growth in almost half of patients with alopecia areata after 7 months.³² Another randomized trial comparing rosemary oil to minoxidil 2% for androgenetic alopecia showed a significant increase in hair count at the 6-month endpoint compared with the baseline, but no significant difference was found between the study groups regarding hair count either at Month 3 or Month 6 (P >.05). ³¹

Adverse effects

In the randomized trial described above comparing rosemary oil to minoxidil 2%, adverse effects appeared to be rare for topical rosemary oil. Scalp itching was more frequent in the minoxidil group.³¹

The bottom line

Topical rosemary oil may be useful in the treatment of alopecia with minimal adverse effects.

Overview

Coffee is one of the most widely used botanicals with approximately 3.5 billion cups of coffee consumed per day worldwide. It is a popular beverage because of its unique aromatic taste and its use as a central nervous system stimulant. The coffee tree (genus coffea) is found throughout Latin America, Africa, and eastern Asia. Two of the most common commercially grown species are Coffea arabica (Arabicas) and Coffea canephora (Robusta). Processing and roasting methods may differ and produce variations in flavor and aroma. The degree of roasting also affects the caffeine content.

Coffee consumption leads to increased alertness and can boost mental performance. Based on the literature and US Food and Drug Administration recommendations, four 8-oz cups of coffee (about 400 mg of caffeine) daily is an acceptable average amount of caffeine. More than 500 mg/d is considered excessive use of coffee.^33,34

Overall mortality. A 2008 study showed that regular coffee was not associated with increased or decreased mortality in both men and women.³⁵ However, more recent studies show an inverse relationship between mortality and coffee consumption.

Specifically, a 2014 meta-analysis found an inverse relationship between coffee and mortality.³⁶ A large prospective cohort study from 2015 that included 79,234 women and 76,704 men found that drinking coffee was inversely associated with overall mortality.³⁷ In this cohort study, an inverse association were observed for deaths from heart disease, respiratory disease, diabetes, and self-harm.³⁷ While mechanisms were not analyzed, coffee may reduce mortality risk by affecting inflammation, lung function, insulin sensitivity, and depression.

Cardiovascular disease. Coffee consumption may modestly reduce the risk of stroke, according to a prospective cohort study of 83,076 women from the Nurses’ Health Study who were followed for 24 years.³⁸ Reduced cardiovascular mortality was also found in a large prospective cohort study, as noted in the mortality discussion above.³⁷ A 2014 meta-analysis concluded that coffee consumption is inversely associated with cardiovascular mortality. Drinking 3 or 4 cups a day appears to be the amount that may decrease one’s risk of death when compared to those who do not drink coffee at all.³⁶

Liver disease. Friedrich et al performed a study involving 379 patients with end stage liver disease, and found that coffee consumption delayed the progression of disease in patients with both alcoholic liver disease and primary sclerosing cholangitis.³⁹ Coffee consumption also increased long-term survival after liver transplantation.³⁹ However, the study found that coffee did not have any effect on patients with chronic viral hepatitis.

In a 2016 meta-analysis, caffeinated coffee consumption reduced hepatic fibrosis of nonalcoholic fatty liver disease, although caffeine consumption did not reduce the prevalence of nonalcoholic fatty liver disease.⁴⁰ Another meta-analysis, including 16 studies, also found caffeine reduced the risk for hepatic fibrosis and cirrhosis.⁴¹

Depression. Based on 2 different systematic reviews and meta-analyses from 2016, coffee consumption appears to have a significant protective effect, decreasing the risk of developing depression.^40,42

Alzheimer’s disease/dementia. Coffee, tea, and caffeine consumption show promise in reducing the risk of cognitive decline and dementia. Individuals who consume one to 2 cups of coffee per day had a decreased incidence of mild cognitive impairment compared to non-drinkers.⁴³ A 2015 Japanese study also found an inverse association between coffee consumption and dementia among women, nonsmokers, and those who do not drink alcohol.⁴⁴ Most recently, a 2016 study, the Women’s Health Initiative Memory Study, looked at incident dementia rates in women >65 years of age with high vs low caffeine intake. Women with higher caffeine intake were less likely to develop dementia or any cognitive impairment compared with those consuming <64 mg/day.⁴⁵

Type 2 diabetes. A 2009 prospective cohort study, which included 40,011 participants followed for more than 10 years, found that drinking at least 3 cups of coffee or tea was associated with a lowered risk of type 2 diabetes.⁴⁶ A 2009 systematic review of 20 cohort studies showed that high intakes of coffee, decaffeinated coffee, and tea are associated with a reduced risk of diabetes.⁴⁷

A meta-analysis of 12 studies involving 832,956 participants found an inverse relationship between cutaneous melanoma and coffee consumption.

Melanoma. A meta-analysis of 12 studies involving 832,956 participants demon­strated an inverse relationship between cutaneous melanoma and coffee consumption.⁴⁷ The risk of melanoma decreased by 3% and 4% for one cup/day of total coffee and caffeinated coffee consumption, respectively. Furthermore, a 2016 meta-analysis found that caffeinated coffee may have greater chemopreventive effects against melanoma than decaffeinated coffee.⁴⁸

Adverse effects

Despite the many potential benefits of coffee, caffeine is a potent drug that should be used with caution.⁴⁹ People with underlying heart problems should avoid caffeine due to concern that it may cause palpitations from tachycardia. It may worsen anxiety problems or depression. Coffee may increase the production of stomach acids, which can worsen acid reflux or stomach ulcers.

Regular coffee intake is associated with a lower risk of mortality, reduced CV events, and a reduction in liver disease progression.

Caffeine is a potent diuretic and may decrease absorption of calcium and cause OA. Caffeine may cause dependence and withdrawal symptoms. Some of the symptoms of withdrawal include drowsiness, headaches, irritability, nausea, and vomiting. It may disrupt sleeping patterns by causing jitters and sleeplessness.⁴⁹ Additionally, large amounts of caffeine may cause overdose and death.

The bottom line

Regular coffee intake is associated with a lower risk of mortality, reduced cardiovascular events, and a reduction in liver disease progression. Coffee may also have some utility for improving cognitive function and reducing the risk of type 2 diabetes. Caffeinated coffee should be limited to no more than 32 oz per day, due to the risk of insomnia, palpitations, anxiety, and gastritis.

Overview

Few natural products have been claimed to successfully treat as many disorders as chocolate. The modern concept of chocolate as food has overshadowed its traditional medicinal use, although recent trials have looked at evidence for some of its traditional uses. Chocolate is processed from the pod of the cacao plant. The earliest evidence for its medical use is in Mayan civilizations, and for most of its approximately 4000-year history, chocolate was consumed as a bitter drink referred to as the “drink of the Gods.” The traditional drink was mixed with water, vanilla, honey, chili peppers, and other spices. Important components in chocolate include flavonoids (antioxidants), cocoa butter, caffeine, theobromine, and phenylethylamine.  

Chocolate has stimulating, anti-inflammatory, neuroprotective, and cardioprotective effects, and improves the bioavailability of nitric oxide, which can improve blood pressure and platelet function.⁵⁰ Epicatechin (an antioxidant) in cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated by the anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-kappaB.⁵¹

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.

Dark chocolate appears to have the greatest benefit, as milk binds to antioxidants in chocolate, making them unavailable. Therefore, milk chocolate is not a good antioxidant source. There is no specific amount of chocolate that is known to be ideal, but an average of one to 2 ounces per day is often used in studies.

Cardiovascular effects. Chocolate does contain saturated fat, but a comparative, double-blind study found that short-term use of cocoa powder lowered plasma low-density lipoprotein (LDL) cholesterol, oxidized LDL, and apo B concentrations, and the plasma high-density lipoprotein (HDL) cholesterol concentration increased, relative to baseline in the low-, middle-, and high-cocoa groups.⁵² A small randomized crossover trial without clinical outcomes indicated that chocolate may increase HDL cholesterol without increasing weight.⁵³

A meta-analysis of short-term (2-12 weeks) treatment with dark chocolate/cocoa products showed reductions in LDL and total cholesterol, but no changes in HDL or triglycerides.⁵⁴ Another meta-analysis of RCTs, however, showed no short-term effect of cocoa/chocolate on lipid concentrations.⁵⁵ A randomized, placebo-controlled double-blind study of 62 patients with diabetes and hypertension showed that high polyphenol chocolate improved triglyceride levels.⁵⁶

Chocolate intake was associated with a lower risk of cognitive decline, with the greatest benefit noted in those who averaged more than one chocolate bar per week.

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.^57-59 A best case scenario analysis using a Markov model to predict the long-term effectiveness and cost effectiveness of daily dark chocolate consumption in a population with metabolic syndrome at high risk of cardiovascular disease concluded that daily consumption of dark chocolate can reduce cardiovascular events by 85 per 10,000 population treated over 10 years. The study concluded that $42 could be cost effectively spent per person per year on prevention strategies using dark chocolate.⁵⁹

In addition, a meta-analysis of 7 observational studies showed that high levels of chocolate consumption (any type) were associated with a 29% reduction in stroke compared with the lowest levels of chocolate intake.⁵⁷ Results of a similar meta-analysis from Neurology in 2012 also suggested that moderate chocolate consumption (any type) may lower the risk of stroke.⁶⁰

That said, 2 systematic reviews specifically relating to the risk of coronary heart disease and chocolate intake were inconclusive.^61-62

Blood pressure (BP). An RCT published in JAMA indicates that inclusion of small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced BP and improved the formation of vasodilative nitric oxide.⁶³ A meta-analysis of 10 RCTs also showed mean BP change in the active cocoa treatment arms across all trials was -4.5 mm Hg (95% confidence interval (CI), -5.9 to -3.2; P<.001) for systolic BP and -2.5 mm Hg (95% CI, -3.9 to -1.2; P<.001) for diastolic BP.⁶⁴

A Cochrane Review meta-analysis of 20 studies revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products compared with control in short-term trials of 2 to 18 weeks' duration.⁶⁵ Because studies have shown improvement in BP with chocolate intake, investigations into a role of chocolate in the prevention of preeclampsia have been undertaken. In some studies, chocolate intake was associated with reduced odds of preeclampsia and gestational hypertension.^66,67

Diabetes. Chocolate may exert significant vascular protection because of its antioxidant properties and possible increase of nitric oxide bioavailability, which can influence glucose uptake. A small trial comparing the effects of either dark or white chocolate bars (which do not contain the polyphenols) showed improved BP and glucose and insulin responses to an oral glucose tolerance test in healthy subjects on dark chocolate, but not white chocolate.⁶⁸ A comparison of chocolate consumption and risk of diabetes in the Physicians’ Health Study showed an inverse relationship between chocolate intake with incident disease, but this association appeared only to apply in younger and normal-body weight men after controlling for comprehensive lifestyles, including total energy consumption.⁶⁹

Fatigue. The effect of chocolate on a person’s energy level has been noted for centuries.⁷⁰ A small randomized trial showed improved energy levels in those treated with higher chocolate intakes. In a double-blind, randomized, clinical pilot crossover study, high cocoa liquor/polyphenol rich chocolate, reduced fatigue in subjects with chronic fatigue syndrome.⁷¹

Anxiety. A small randomized trial showed chocolate decreased anxiety in high-anxiety trait subjects and improved the anxiety level and the energy levels of low-anxiety trait participants.⁷²

Eye effects. The literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension. However, a meta-analysis showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension, and appear to play a part in both improving and slowing the progression of visual field loss.⁷³

Cognitive decline. Chocolate intake (any type) was associated with a lower risk of cognitive decline (RR = 0.59; 95% CI, 0.38-0.92) with the greatest benefit noted in those who averaged more than one chocolate bar or one tablespoon of cocoa powder per week. This protective effect was observed only among subjects with an average daily consumption of caffeine <75  mg (69% of the participants; RR = 0.50; 95% CI, 0.31-0.82).⁷⁴

The bottom line

Chocolate with high cocoa content (dark chocolate) appears to be safe and beneficial as part of a healthy diet and lifestyle that includes exercise and stress reduction to decrease cardiovascular risk and may improve energy levels.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.

Overview

Chamomile, a member of the Asteraceae/Compositae family, is one of the oldest herbal medicines. It has been used for hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations have been developed, the most popular being herbal tea.²⁴

A controlled clinical trial of chamomile extract suggested that it may have modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Individuals with a hypersensitivity to plants of the Asteraceae (Compositae) family such as ragweed (Ambrosia spp.), marigold flower (Calendula officinalis), and chrysanthemum (Chrysanthemum spp.) may show a similar reaction to chamomile.²⁵

Anxiety. A controlled clinical trial of chamomile extract for generalized anxiety disorder (GAD) suggested that it may have modest anxiolytic activity in patients with mild to moderate GAD.²⁶ Another randomized, double-blind, placebo-controlled trial found oral chamomile extract was efficacious and well-tolerated in patients experiencing mild to moderate GAD and may provide an alternative therapeutic anxiolytic for patients with mild GAD.²⁵ In addition to its anxiolytic activity, chamomile may also provide clinically meaningful antidepressant activity.²⁶

Insomnia. Chamomile may have some impact on sleep diary measures (total sleep time, sleep efficiency, sleep latency, wake after sleep onset, sleep quality, and number of awakenings) relative to placebo in adults with chronic primary insomnia, according to a small randomized, double-blind, placebo-controlled pilot trial involving 34 patients.²⁷ However, a systematic review found no statistically significant difference between any herbal medicine (including chamomile) and placebo, for clinical efficacy in patients with insomnia. A similar, or smaller, number of adverse events per person were reported with chamomile compared with placebo, suggesting safe use.²⁸

Infantile colic. A small prospective double-blind study on the use of chamomile-containing tea on infantile colic showed statistically significant symptom improvement in tea-treated infants. The study did note, however, that prolonged ingestion of herbal teas may lead to decreased milk intake.^29,30

Adverse effects

As noted earlier, a systematic review found that the number of adverse events per person reported with chamomile was comparable to the number associated with placebo, suggesting that it is safe.²⁸

The bottom line

Chamomile appears to be safe with minimal adverse effects and may be effective for the treatment of anxiety, insomnia, and infantile colic.

Rosemary

Overview

Rosemary, officially known as Rosmarinus officinalis, is a medicinal evergreen plant native to the Mediterranean area that appears to increase microcapillary perfusion.³¹

Topical rosemary oil may be useful in the treatment of alopecia, with minimal adverse effects.

Alopecia. A randomized double-blind controlled trial found that essential oils including rosemary oil (as well as thyme, lavender, and cedarwood) massaged into the scalp improved hair growth in almost half of patients with alopecia areata after 7 months.³² Another randomized trial comparing rosemary oil to minoxidil 2% for androgenetic alopecia showed a significant increase in hair count at the 6-month endpoint compared with the baseline, but no significant difference was found between the study groups regarding hair count either at Month 3 or Month 6 (P >.05). ³¹

Adverse effects

In the randomized trial described above comparing rosemary oil to minoxidil 2%, adverse effects appeared to be rare for topical rosemary oil. Scalp itching was more frequent in the minoxidil group.³¹

The bottom line

Topical rosemary oil may be useful in the treatment of alopecia with minimal adverse effects.

Overview

Coffee is one of the most widely used botanicals with approximately 3.5 billion cups of coffee consumed per day worldwide. It is a popular beverage because of its unique aromatic taste and its use as a central nervous system stimulant. The coffee tree (genus coffea) is found throughout Latin America, Africa, and eastern Asia. Two of the most common commercially grown species are Coffea arabica (Arabicas) and Coffea canephora (Robusta). Processing and roasting methods may differ and produce variations in flavor and aroma. The degree of roasting also affects the caffeine content.

Coffee consumption leads to increased alertness and can boost mental performance. Based on the literature and US Food and Drug Administration recommendations, four 8-oz cups of coffee (about 400 mg of caffeine) daily is an acceptable average amount of caffeine. More than 500 mg/d is considered excessive use of coffee.^33,34

Overall mortality. A 2008 study showed that regular coffee was not associated with increased or decreased mortality in both men and women.³⁵ However, more recent studies show an inverse relationship between mortality and coffee consumption.

Specifically, a 2014 meta-analysis found an inverse relationship between coffee and mortality.³⁶ A large prospective cohort study from 2015 that included 79,234 women and 76,704 men found that drinking coffee was inversely associated with overall mortality.³⁷ In this cohort study, an inverse association were observed for deaths from heart disease, respiratory disease, diabetes, and self-harm.³⁷ While mechanisms were not analyzed, coffee may reduce mortality risk by affecting inflammation, lung function, insulin sensitivity, and depression.

Cardiovascular disease. Coffee consumption may modestly reduce the risk of stroke, according to a prospective cohort study of 83,076 women from the Nurses’ Health Study who were followed for 24 years.³⁸ Reduced cardiovascular mortality was also found in a large prospective cohort study, as noted in the mortality discussion above.³⁷ A 2014 meta-analysis concluded that coffee consumption is inversely associated with cardiovascular mortality. Drinking 3 or 4 cups a day appears to be the amount that may decrease one’s risk of death when compared to those who do not drink coffee at all.³⁶

Liver disease. Friedrich et al performed a study involving 379 patients with end stage liver disease, and found that coffee consumption delayed the progression of disease in patients with both alcoholic liver disease and primary sclerosing cholangitis.³⁹ Coffee consumption also increased long-term survival after liver transplantation.³⁹ However, the study found that coffee did not have any effect on patients with chronic viral hepatitis.

In a 2016 meta-analysis, caffeinated coffee consumption reduced hepatic fibrosis of nonalcoholic fatty liver disease, although caffeine consumption did not reduce the prevalence of nonalcoholic fatty liver disease.⁴⁰ Another meta-analysis, including 16 studies, also found caffeine reduced the risk for hepatic fibrosis and cirrhosis.⁴¹

Depression. Based on 2 different systematic reviews and meta-analyses from 2016, coffee consumption appears to have a significant protective effect, decreasing the risk of developing depression.^40,42

Alzheimer’s disease/dementia. Coffee, tea, and caffeine consumption show promise in reducing the risk of cognitive decline and dementia. Individuals who consume one to 2 cups of coffee per day had a decreased incidence of mild cognitive impairment compared to non-drinkers.⁴³ A 2015 Japanese study also found an inverse association between coffee consumption and dementia among women, nonsmokers, and those who do not drink alcohol.⁴⁴ Most recently, a 2016 study, the Women’s Health Initiative Memory Study, looked at incident dementia rates in women >65 years of age with high vs low caffeine intake. Women with higher caffeine intake were less likely to develop dementia or any cognitive impairment compared with those consuming <64 mg/day.⁴⁵

Type 2 diabetes. A 2009 prospective cohort study, which included 40,011 participants followed for more than 10 years, found that drinking at least 3 cups of coffee or tea was associated with a lowered risk of type 2 diabetes.⁴⁶ A 2009 systematic review of 20 cohort studies showed that high intakes of coffee, decaffeinated coffee, and tea are associated with a reduced risk of diabetes.⁴⁷

A meta-analysis of 12 studies involving 832,956 participants found an inverse relationship between cutaneous melanoma and coffee consumption.

Melanoma. A meta-analysis of 12 studies involving 832,956 participants demon­strated an inverse relationship between cutaneous melanoma and coffee consumption.⁴⁷ The risk of melanoma decreased by 3% and 4% for one cup/day of total coffee and caffeinated coffee consumption, respectively. Furthermore, a 2016 meta-analysis found that caffeinated coffee may have greater chemopreventive effects against melanoma than decaffeinated coffee.⁴⁸

Adverse effects

Despite the many potential benefits of coffee, caffeine is a potent drug that should be used with caution.⁴⁹ People with underlying heart problems should avoid caffeine due to concern that it may cause palpitations from tachycardia. It may worsen anxiety problems or depression. Coffee may increase the production of stomach acids, which can worsen acid reflux or stomach ulcers.

Regular coffee intake is associated with a lower risk of mortality, reduced CV events, and a reduction in liver disease progression.

Caffeine is a potent diuretic and may decrease absorption of calcium and cause OA. Caffeine may cause dependence and withdrawal symptoms. Some of the symptoms of withdrawal include drowsiness, headaches, irritability, nausea, and vomiting. It may disrupt sleeping patterns by causing jitters and sleeplessness.⁴⁹ Additionally, large amounts of caffeine may cause overdose and death.

The bottom line

Regular coffee intake is associated with a lower risk of mortality, reduced cardiovascular events, and a reduction in liver disease progression. Coffee may also have some utility for improving cognitive function and reducing the risk of type 2 diabetes. Caffeinated coffee should be limited to no more than 32 oz per day, due to the risk of insomnia, palpitations, anxiety, and gastritis.

Overview

Few natural products have been claimed to successfully treat as many disorders as chocolate. The modern concept of chocolate as food has overshadowed its traditional medicinal use, although recent trials have looked at evidence for some of its traditional uses. Chocolate is processed from the pod of the cacao plant. The earliest evidence for its medical use is in Mayan civilizations, and for most of its approximately 4000-year history, chocolate was consumed as a bitter drink referred to as the “drink of the Gods.” The traditional drink was mixed with water, vanilla, honey, chili peppers, and other spices. Important components in chocolate include flavonoids (antioxidants), cocoa butter, caffeine, theobromine, and phenylethylamine.  

Chocolate has stimulating, anti-inflammatory, neuroprotective, and cardioprotective effects, and improves the bioavailability of nitric oxide, which can improve blood pressure and platelet function.⁵⁰ Epicatechin (an antioxidant) in cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated by the anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-kappaB.⁵¹

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.

Dark chocolate appears to have the greatest benefit, as milk binds to antioxidants in chocolate, making them unavailable. Therefore, milk chocolate is not a good antioxidant source. There is no specific amount of chocolate that is known to be ideal, but an average of one to 2 ounces per day is often used in studies.

Cardiovascular effects. Chocolate does contain saturated fat, but a comparative, double-blind study found that short-term use of cocoa powder lowered plasma low-density lipoprotein (LDL) cholesterol, oxidized LDL, and apo B concentrations, and the plasma high-density lipoprotein (HDL) cholesterol concentration increased, relative to baseline in the low-, middle-, and high-cocoa groups.⁵² A small randomized crossover trial without clinical outcomes indicated that chocolate may increase HDL cholesterol without increasing weight.⁵³

A meta-analysis of short-term (2-12 weeks) treatment with dark chocolate/cocoa products showed reductions in LDL and total cholesterol, but no changes in HDL or triglycerides.⁵⁴ Another meta-analysis of RCTs, however, showed no short-term effect of cocoa/chocolate on lipid concentrations.⁵⁵ A randomized, placebo-controlled double-blind study of 62 patients with diabetes and hypertension showed that high polyphenol chocolate improved triglyceride levels.⁵⁶

Chocolate intake was associated with a lower risk of cognitive decline, with the greatest benefit noted in those who averaged more than one chocolate bar per week.

Multiple studies have shown that chocolate is associated with a reduction in cardiovascular risk.^57-59 A best case scenario analysis using a Markov model to predict the long-term effectiveness and cost effectiveness of daily dark chocolate consumption in a population with metabolic syndrome at high risk of cardiovascular disease concluded that daily consumption of dark chocolate can reduce cardiovascular events by 85 per 10,000 population treated over 10 years. The study concluded that $42 could be cost effectively spent per person per year on prevention strategies using dark chocolate.⁵⁹

In addition, a meta-analysis of 7 observational studies showed that high levels of chocolate consumption (any type) were associated with a 29% reduction in stroke compared with the lowest levels of chocolate intake.⁵⁷ Results of a similar meta-analysis from Neurology in 2012 also suggested that moderate chocolate consumption (any type) may lower the risk of stroke.⁶⁰

That said, 2 systematic reviews specifically relating to the risk of coronary heart disease and chocolate intake were inconclusive.^61-62

Blood pressure (BP). An RCT published in JAMA indicates that inclusion of small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced BP and improved the formation of vasodilative nitric oxide.⁶³ A meta-analysis of 10 RCTs also showed mean BP change in the active cocoa treatment arms across all trials was -4.5 mm Hg (95% confidence interval (CI), -5.9 to -3.2; P<.001) for systolic BP and -2.5 mm Hg (95% CI, -3.9 to -1.2; P<.001) for diastolic BP.⁶⁴

A Cochrane Review meta-analysis of 20 studies revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products compared with control in short-term trials of 2 to 18 weeks' duration.⁶⁵ Because studies have shown improvement in BP with chocolate intake, investigations into a role of chocolate in the prevention of preeclampsia have been undertaken. In some studies, chocolate intake was associated with reduced odds of preeclampsia and gestational hypertension.^66,67

Diabetes. Chocolate may exert significant vascular protection because of its antioxidant properties and possible increase of nitric oxide bioavailability, which can influence glucose uptake. A small trial comparing the effects of either dark or white chocolate bars (which do not contain the polyphenols) showed improved BP and glucose and insulin responses to an oral glucose tolerance test in healthy subjects on dark chocolate, but not white chocolate.⁶⁸ A comparison of chocolate consumption and risk of diabetes in the Physicians’ Health Study showed an inverse relationship between chocolate intake with incident disease, but this association appeared only to apply in younger and normal-body weight men after controlling for comprehensive lifestyles, including total energy consumption.⁶⁹

Fatigue. The effect of chocolate on a person’s energy level has been noted for centuries.⁷⁰ A small randomized trial showed improved energy levels in those treated with higher chocolate intakes. In a double-blind, randomized, clinical pilot crossover study, high cocoa liquor/polyphenol rich chocolate, reduced fatigue in subjects with chronic fatigue syndrome.⁷¹

Anxiety. A small randomized trial showed chocolate decreased anxiety in high-anxiety trait subjects and improved the anxiety level and the energy levels of low-anxiety trait participants.⁷²

Eye effects. The literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension. However, a meta-analysis showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension, and appear to play a part in both improving and slowing the progression of visual field loss.⁷³

Cognitive decline. Chocolate intake (any type) was associated with a lower risk of cognitive decline (RR = 0.59; 95% CI, 0.38-0.92) with the greatest benefit noted in those who averaged more than one chocolate bar or one tablespoon of cocoa powder per week. This protective effect was observed only among subjects with an average daily consumption of caffeine <75  mg (69% of the participants; RR = 0.50; 95% CI, 0.31-0.82).⁷⁴

The bottom line

Chocolate with high cocoa content (dark chocolate) appears to be safe and beneficial as part of a healthy diet and lifestyle that includes exercise and stress reduction to decrease cardiovascular risk and may improve energy levels.

CORRESPONDENCE
Michael Malone, MD, Family and Community Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033; [email protected].