Obesity

TOPLINE:

Higher dietary niacin intake is associated with a lower risk for all-cause mortality among people with metabolic dysfunction-associated steatotic liver disease (MASLD), but there is no connection between niacin consumption and cardiovascular disease (CVD) mortality, a recent study suggested.

METHODOLOGY:

• Researchers analyzed data from the National Health and Nutrition Examination Survey (2003-2018) for 4315 adults with MASLD (mean age, 52.5 years; 55%, men; 67%, non-Hispanic White).
• Dietary niacin intake levels were based on two 24-hour dietary recall interviews to report the types and quantities of foods that participants consumed in the 24 hours prior to the interviews.
• Participants were categorized by tertile of dietary niacin intake: Tertile 1 (n = 1440), < 18.4 mg; tertile 2 (n = 1441), 18.5-26.6 mg; and tertile 3 (n = 1434), > 26.7 mg.

TAKEAWAY:

• During a median follow-up of 8.8 years, 566 deaths occurred, of which 197 were attributed to CVD.
• Compared with participants with a niacin intake of 18.4 mg or lower (the lowest tertile), the multivariable-adjusted hazard ratios (HRs) for participants with a niacin intake of 26.7 mg or higher (the highest tertile) were 0.70 for all-cause mortality and 0.65 for CVD mortality.
• For the subgroup with diabetes compared with the reference group (the first tertile), the HR of all-cause mortality in the third tertile was 0.82.
• When the subgroup without diabetes was compared with the reference group, the HR of all-cause mortality in the third tertile was 0.58, suggesting a significant interaction between niacin and diabetes with the risk of all-cause mortality.
• An inverse association between dietary niacin intake and all-cause mortality was seen in sensitivity analyses, when excluding a participant who died within 2 years of follow-up.

IN PRACTICE:

“Higher dietary niacin intake was associated with a lower risk of all-cause mortality,” but not CVD, among individuals with MASLD, and “the dose-response association…needs to be further investigated to determine optimal intake level,” the authors wrote.

SOURCE:

The study, led by Jie Pan, MD, Sun Yat-sen University, Guangzhou, China, was published online in JAMA Network Open.

LIMITATIONS:

Physical activity data were missing and could not be adjusted for. The National Death Index used by the researchers has only “modest” ability to accurately classify CVD mortality, and the dietary data were subject to recall bias.

DISCLOSURES:

One author was supported by a grant from the National Nature Science Foundation of China. No other conflicts of interest were reported.

A version of this article appeared on Medscape.com.

TOPLINE:

Higher dietary niacin intake is associated with a lower risk for all-cause mortality among people with metabolic dysfunction-associated steatotic liver disease (MASLD), but there is no connection between niacin consumption and cardiovascular disease (CVD) mortality, a recent study suggested.

METHODOLOGY:

• Researchers analyzed data from the National Health and Nutrition Examination Survey (2003-2018) for 4315 adults with MASLD (mean age, 52.5 years; 55%, men; 67%, non-Hispanic White).
• Dietary niacin intake levels were based on two 24-hour dietary recall interviews to report the types and quantities of foods that participants consumed in the 24 hours prior to the interviews.
• Participants were categorized by tertile of dietary niacin intake: Tertile 1 (n = 1440), < 18.4 mg; tertile 2 (n = 1441), 18.5-26.6 mg; and tertile 3 (n = 1434), > 26.7 mg.

TAKEAWAY:

• During a median follow-up of 8.8 years, 566 deaths occurred, of which 197 were attributed to CVD.
• Compared with participants with a niacin intake of 18.4 mg or lower (the lowest tertile), the multivariable-adjusted hazard ratios (HRs) for participants with a niacin intake of 26.7 mg or higher (the highest tertile) were 0.70 for all-cause mortality and 0.65 for CVD mortality.
• For the subgroup with diabetes compared with the reference group (the first tertile), the HR of all-cause mortality in the third tertile was 0.82.
• When the subgroup without diabetes was compared with the reference group, the HR of all-cause mortality in the third tertile was 0.58, suggesting a significant interaction between niacin and diabetes with the risk of all-cause mortality.
• An inverse association between dietary niacin intake and all-cause mortality was seen in sensitivity analyses, when excluding a participant who died within 2 years of follow-up.

IN PRACTICE:

“Higher dietary niacin intake was associated with a lower risk of all-cause mortality,” but not CVD, among individuals with MASLD, and “the dose-response association…needs to be further investigated to determine optimal intake level,” the authors wrote.

SOURCE:

The study, led by Jie Pan, MD, Sun Yat-sen University, Guangzhou, China, was published online in JAMA Network Open.

LIMITATIONS:

Physical activity data were missing and could not be adjusted for. The National Death Index used by the researchers has only “modest” ability to accurately classify CVD mortality, and the dietary data were subject to recall bias.

DISCLOSURES:

One author was supported by a grant from the National Nature Science Foundation of China. No other conflicts of interest were reported.

A version of this article appeared on Medscape.com.

TOPLINE:

Higher dietary niacin intake is associated with a lower risk for all-cause mortality among people with metabolic dysfunction-associated steatotic liver disease (MASLD), but there is no connection between niacin consumption and cardiovascular disease (CVD) mortality, a recent study suggested.

METHODOLOGY:

• Researchers analyzed data from the National Health and Nutrition Examination Survey (2003-2018) for 4315 adults with MASLD (mean age, 52.5 years; 55%, men; 67%, non-Hispanic White).
• Dietary niacin intake levels were based on two 24-hour dietary recall interviews to report the types and quantities of foods that participants consumed in the 24 hours prior to the interviews.
• Participants were categorized by tertile of dietary niacin intake: Tertile 1 (n = 1440), < 18.4 mg; tertile 2 (n = 1441), 18.5-26.6 mg; and tertile 3 (n = 1434), > 26.7 mg.

TAKEAWAY:

• During a median follow-up of 8.8 years, 566 deaths occurred, of which 197 were attributed to CVD.
• Compared with participants with a niacin intake of 18.4 mg or lower (the lowest tertile), the multivariable-adjusted hazard ratios (HRs) for participants with a niacin intake of 26.7 mg or higher (the highest tertile) were 0.70 for all-cause mortality and 0.65 for CVD mortality.
• For the subgroup with diabetes compared with the reference group (the first tertile), the HR of all-cause mortality in the third tertile was 0.82.
• When the subgroup without diabetes was compared with the reference group, the HR of all-cause mortality in the third tertile was 0.58, suggesting a significant interaction between niacin and diabetes with the risk of all-cause mortality.
• An inverse association between dietary niacin intake and all-cause mortality was seen in sensitivity analyses, when excluding a participant who died within 2 years of follow-up.

IN PRACTICE:

“Higher dietary niacin intake was associated with a lower risk of all-cause mortality,” but not CVD, among individuals with MASLD, and “the dose-response association…needs to be further investigated to determine optimal intake level,” the authors wrote.

SOURCE:

The study, led by Jie Pan, MD, Sun Yat-sen University, Guangzhou, China, was published online in JAMA Network Open.

LIMITATIONS:

Physical activity data were missing and could not be adjusted for. The National Death Index used by the researchers has only “modest” ability to accurately classify CVD mortality, and the dietary data were subject to recall bias.

DISCLOSURES:

One author was supported by a grant from the National Nature Science Foundation of China. No other conflicts of interest were reported.

A version of this article appeared on Medscape.com.

TOPLINE:

Patients on weekly glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have high residual gastric content, a major risk factor for aspiration under anesthesia, despite following fasting guidelines before undergoing elective procedures.

METHODOLOGY:

• The increasing use of GLP-1 RAs to manage weight and hyperglycemia has sparked safety concerns because of the drugs’ association with slow gastric emptying, a major risk factor for aspiration under anesthesia.
• This cross-sectional study used gastric ultrasonography to examine the link between GLP-1 RA use and the prevalence of increased residual gastric content.
• All 124 participants (median age, 56 years; 60% women) — half of whom received once-weekly GLP-1 RAs such as semaglutide, dulaglutide, or tirzepatide — adhered to the guideline-recommended fasting duration before undergoing elective procedures under anesthesia.
• The primary outcome focused on identifying increased residual gastric content, defined by the presence of solids, thick liquids, or > 1.5 mL/kg of clear liquids on ultrasound.
• An exploratory analysis examined the association between the duration of GLP-1 RA discontinuation and increased residual gastric content.

TAKEAWAY:

• The adjusted prevalence of increased residual gastric content was 30.5% (95% CI, 9.9%-51.2%) higher in participants who received GLP-1 RA than those who did not.
• Most patients took their last dose of GLP-1 RA within 5 days before their procedure, but elevated residual gastric content persisted even after 7 days of GLP-1 RA discontinuation.
• There was also no significant association between the type of GLP-1 RA used and the prevalence of increased residual gastric content.

IN PRACTICE:

“We expect healthcare professionals will encounter these classes of drugs with increasing frequency in the perioperative period. Perioperative physicians, including anesthesiologists, surgeons, and primary care physicians, should be well-informed about the safety implications of GLP-1 RA drugs,” the authors wrote.

SOURCE:

The study was led by Sudipta Sen, MD, from the Department of Anesthesiology, Critical Care and Pain Medicine, McGovern Medical School, University of Texas Health Center at Houston, Houston, Texas, and published online in JAMA Surgery.

LIMITATIONS:

Residual gastric content, the primary outcome, served as a proxy for aspiration risk and does not have an exact threshold of volume associated with increased risk. The study did not directly evaluate aspiration events. The authors also acknowledged potential bias from unmeasured confounders owing to the observational nature of this study. A small sample size limited the ability to detect a risk difference for each additional day of drug discontinuation before surgery.

DISCLOSURES:

One of the authors reported receiving a grant from the National Institutes of Health. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

TOPLINE:

Patients on weekly glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have high residual gastric content, a major risk factor for aspiration under anesthesia, despite following fasting guidelines before undergoing elective procedures.

METHODOLOGY:

• The increasing use of GLP-1 RAs to manage weight and hyperglycemia has sparked safety concerns because of the drugs’ association with slow gastric emptying, a major risk factor for aspiration under anesthesia.
• This cross-sectional study used gastric ultrasonography to examine the link between GLP-1 RA use and the prevalence of increased residual gastric content.
• All 124 participants (median age, 56 years; 60% women) — half of whom received once-weekly GLP-1 RAs such as semaglutide, dulaglutide, or tirzepatide — adhered to the guideline-recommended fasting duration before undergoing elective procedures under anesthesia.
• The primary outcome focused on identifying increased residual gastric content, defined by the presence of solids, thick liquids, or > 1.5 mL/kg of clear liquids on ultrasound.
• An exploratory analysis examined the association between the duration of GLP-1 RA discontinuation and increased residual gastric content.

TAKEAWAY:

• The adjusted prevalence of increased residual gastric content was 30.5% (95% CI, 9.9%-51.2%) higher in participants who received GLP-1 RA than those who did not.
• Most patients took their last dose of GLP-1 RA within 5 days before their procedure, but elevated residual gastric content persisted even after 7 days of GLP-1 RA discontinuation.
• There was also no significant association between the type of GLP-1 RA used and the prevalence of increased residual gastric content.

IN PRACTICE:

“We expect healthcare professionals will encounter these classes of drugs with increasing frequency in the perioperative period. Perioperative physicians, including anesthesiologists, surgeons, and primary care physicians, should be well-informed about the safety implications of GLP-1 RA drugs,” the authors wrote.

SOURCE:

The study was led by Sudipta Sen, MD, from the Department of Anesthesiology, Critical Care and Pain Medicine, McGovern Medical School, University of Texas Health Center at Houston, Houston, Texas, and published online in JAMA Surgery.

LIMITATIONS:

Residual gastric content, the primary outcome, served as a proxy for aspiration risk and does not have an exact threshold of volume associated with increased risk. The study did not directly evaluate aspiration events. The authors also acknowledged potential bias from unmeasured confounders owing to the observational nature of this study. A small sample size limited the ability to detect a risk difference for each additional day of drug discontinuation before surgery.

DISCLOSURES:

One of the authors reported receiving a grant from the National Institutes of Health. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

TOPLINE:

Patients on weekly glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have high residual gastric content, a major risk factor for aspiration under anesthesia, despite following fasting guidelines before undergoing elective procedures.

METHODOLOGY:

• The increasing use of GLP-1 RAs to manage weight and hyperglycemia has sparked safety concerns because of the drugs’ association with slow gastric emptying, a major risk factor for aspiration under anesthesia.
• This cross-sectional study used gastric ultrasonography to examine the link between GLP-1 RA use and the prevalence of increased residual gastric content.
• All 124 participants (median age, 56 years; 60% women) — half of whom received once-weekly GLP-1 RAs such as semaglutide, dulaglutide, or tirzepatide — adhered to the guideline-recommended fasting duration before undergoing elective procedures under anesthesia.
• The primary outcome focused on identifying increased residual gastric content, defined by the presence of solids, thick liquids, or > 1.5 mL/kg of clear liquids on ultrasound.
• An exploratory analysis examined the association between the duration of GLP-1 RA discontinuation and increased residual gastric content.

TAKEAWAY:

• The adjusted prevalence of increased residual gastric content was 30.5% (95% CI, 9.9%-51.2%) higher in participants who received GLP-1 RA than those who did not.
• Most patients took their last dose of GLP-1 RA within 5 days before their procedure, but elevated residual gastric content persisted even after 7 days of GLP-1 RA discontinuation.
• There was also no significant association between the type of GLP-1 RA used and the prevalence of increased residual gastric content.

IN PRACTICE:

“We expect healthcare professionals will encounter these classes of drugs with increasing frequency in the perioperative period. Perioperative physicians, including anesthesiologists, surgeons, and primary care physicians, should be well-informed about the safety implications of GLP-1 RA drugs,” the authors wrote.

SOURCE:

The study was led by Sudipta Sen, MD, from the Department of Anesthesiology, Critical Care and Pain Medicine, McGovern Medical School, University of Texas Health Center at Houston, Houston, Texas, and published online in JAMA Surgery.

LIMITATIONS:

Residual gastric content, the primary outcome, served as a proxy for aspiration risk and does not have an exact threshold of volume associated with increased risk. The study did not directly evaluate aspiration events. The authors also acknowledged potential bias from unmeasured confounders owing to the observational nature of this study. A small sample size limited the ability to detect a risk difference for each additional day of drug discontinuation before surgery.

DISCLOSURES:

One of the authors reported receiving a grant from the National Institutes of Health. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

Adults with persistent metabolic syndrome that worsens over time are at increased risk for any type of cancer, according to a new study of more than 44,000 individuals.

The conditions that comprise metabolic syndrome (high blood pressure, high blood sugar, increased abdominal adiposity, and high cholesterol and triglycerides) have been associated with an increased risk of diseases, including heart disease, stroke, and type 2 diabetes, wrote Li Deng, PhD, of Capital Medical University, Beijing, China, and colleagues.

A systematic review and meta-analysis published in Diabetes Care in 2012 showed an association between the presence of metabolic syndrome and an increased risk of various cancers including liver, bladder, pancreatic, breast, and colorectal.

More recently, a 2019 study published in Diabetes showed evidence of increased risk for certain cancers (pancreatic, kidney, uterine, cervical) but no increased risk for cancer overall.

However, the reasons for this association between metabolic syndrome and cancer remain unclear, and the effect of the fluctuating nature of metabolic syndrome over time on long-term cancer risk has not been explored, the researchers wrote.
 

What Does New Study Add to Other Research on Metabolic Syndrome and Cancer Risk?

In the new study, published in Cancer on March 11 (doi: 10.1002/cncr.35235), 44,115 adults in China were separated into four trajectories based on metabolic syndrome scores for the period from 2006 to 2010. The scores were based on clinical evidence of metabolic syndrome, defined using the International Diabetes Federation criteria of central obesity and the presence of at least two other factors including increased triglycerides, decreased HDL cholesterol, high blood pressure (or treatment for previously diagnosed hypertension), and increased fasting plasma glucose (or previous diagnosis of type 2 diabetes).

The average age of the participants was 49 years. The four trajectories of metabolic syndrome were low-stable (10.56% of participants), moderate-low (40.84%), moderate-high (41.46%), and elevated-increasing (7.14%), based on trends from the individuals’ initial physical exams on entering the study.

Over a median follow-up period of 9.4 years (from 2010 to 2021), 2,271 cancer diagnoses were reported in the study population. Those with an elevated-increasing metabolic syndrome trajectory had 1.3 times the risk of any cancer compared with those in the low-stable group. Risk for breast cancer, endometrial cancer, kidney cancer, colorectal cancer, and liver cancer in the highest trajectory group were 2.1, 3.3, 4.5, 2.5, and 1.6 times higher, respectively, compared to the lowest group. The increased risk in the elevated-trajectory group for all cancer types persisted when the low-stable, moderate-low, and moderate-high trajectory pattern groups were combined.

The researchers also examined the impact of chronic inflammation and found that individuals with persistently high metabolic syndrome scores and concurrent chronic inflammation had the highest risks of breast, endometrial, colon, and liver cancer. However, individuals with persistently high metabolic syndrome scores and no concurrent chronic inflammation had the highest risk of kidney cancer.
 

 What Are the Limitations of This Research?

The researchers of the current study acknowledged the lack of information on other causes of cancer, including dietary habits, hepatitis C infection, and Helicobacter pylori infection. Other limitations include the focus only on individuals from a single community of mainly middle-aged men in China that may not generalize to other populations.

Also, the metabolic syndrome trajectories did not change much over time, which may be related to the short 4-year study period.
 

What Is the Takeaway Message for Clinical Practice?

The results suggest that monitoring and managing metabolic syndrome could help reduce cancer risk, the researchers concluded. 

“This research suggests that proactive and continuous management of metabolic syndrome may serve as an essential strategy in preventing cancer,” senior author Han-Ping Shi, MD, PhD, of Capital Medical University in Beijing, said in a press release accompanying the study.

More research is needed to assess the impact of these interventions on cancer risk, he noted. However, the data from the current study can guide future research that may lead to more targeted treatments and more effective preventive strategies, he said in a statement.

The study was supported by the National Key Research and Development Program of China. The researchers had no financial conflicts to disclose.

Adults with persistent metabolic syndrome that worsens over time are at increased risk for any type of cancer, according to a new study of more than 44,000 individuals.

The conditions that comprise metabolic syndrome (high blood pressure, high blood sugar, increased abdominal adiposity, and high cholesterol and triglycerides) have been associated with an increased risk of diseases, including heart disease, stroke, and type 2 diabetes, wrote Li Deng, PhD, of Capital Medical University, Beijing, China, and colleagues.

A systematic review and meta-analysis published in Diabetes Care in 2012 showed an association between the presence of metabolic syndrome and an increased risk of various cancers including liver, bladder, pancreatic, breast, and colorectal.

More recently, a 2019 study published in Diabetes showed evidence of increased risk for certain cancers (pancreatic, kidney, uterine, cervical) but no increased risk for cancer overall.

However, the reasons for this association between metabolic syndrome and cancer remain unclear, and the effect of the fluctuating nature of metabolic syndrome over time on long-term cancer risk has not been explored, the researchers wrote.
 

What Does New Study Add to Other Research on Metabolic Syndrome and Cancer Risk?

In the new study, published in Cancer on March 11 (doi: 10.1002/cncr.35235), 44,115 adults in China were separated into four trajectories based on metabolic syndrome scores for the period from 2006 to 2010. The scores were based on clinical evidence of metabolic syndrome, defined using the International Diabetes Federation criteria of central obesity and the presence of at least two other factors including increased triglycerides, decreased HDL cholesterol, high blood pressure (or treatment for previously diagnosed hypertension), and increased fasting plasma glucose (or previous diagnosis of type 2 diabetes).

The average age of the participants was 49 years. The four trajectories of metabolic syndrome were low-stable (10.56% of participants), moderate-low (40.84%), moderate-high (41.46%), and elevated-increasing (7.14%), based on trends from the individuals’ initial physical exams on entering the study.

Over a median follow-up period of 9.4 years (from 2010 to 2021), 2,271 cancer diagnoses were reported in the study population. Those with an elevated-increasing metabolic syndrome trajectory had 1.3 times the risk of any cancer compared with those in the low-stable group. Risk for breast cancer, endometrial cancer, kidney cancer, colorectal cancer, and liver cancer in the highest trajectory group were 2.1, 3.3, 4.5, 2.5, and 1.6 times higher, respectively, compared to the lowest group. The increased risk in the elevated-trajectory group for all cancer types persisted when the low-stable, moderate-low, and moderate-high trajectory pattern groups were combined.

The researchers also examined the impact of chronic inflammation and found that individuals with persistently high metabolic syndrome scores and concurrent chronic inflammation had the highest risks of breast, endometrial, colon, and liver cancer. However, individuals with persistently high metabolic syndrome scores and no concurrent chronic inflammation had the highest risk of kidney cancer.
 

 What Are the Limitations of This Research?

The researchers of the current study acknowledged the lack of information on other causes of cancer, including dietary habits, hepatitis C infection, and Helicobacter pylori infection. Other limitations include the focus only on individuals from a single community of mainly middle-aged men in China that may not generalize to other populations.

Also, the metabolic syndrome trajectories did not change much over time, which may be related to the short 4-year study period.
 

What Is the Takeaway Message for Clinical Practice?

The results suggest that monitoring and managing metabolic syndrome could help reduce cancer risk, the researchers concluded. 

“This research suggests that proactive and continuous management of metabolic syndrome may serve as an essential strategy in preventing cancer,” senior author Han-Ping Shi, MD, PhD, of Capital Medical University in Beijing, said in a press release accompanying the study.

More research is needed to assess the impact of these interventions on cancer risk, he noted. However, the data from the current study can guide future research that may lead to more targeted treatments and more effective preventive strategies, he said in a statement.

The study was supported by the National Key Research and Development Program of China. The researchers had no financial conflicts to disclose.

Adults with persistent metabolic syndrome that worsens over time are at increased risk for any type of cancer, according to a new study of more than 44,000 individuals.

The conditions that comprise metabolic syndrome (high blood pressure, high blood sugar, increased abdominal adiposity, and high cholesterol and triglycerides) have been associated with an increased risk of diseases, including heart disease, stroke, and type 2 diabetes, wrote Li Deng, PhD, of Capital Medical University, Beijing, China, and colleagues.

A systematic review and meta-analysis published in Diabetes Care in 2012 showed an association between the presence of metabolic syndrome and an increased risk of various cancers including liver, bladder, pancreatic, breast, and colorectal.

More recently, a 2019 study published in Diabetes showed evidence of increased risk for certain cancers (pancreatic, kidney, uterine, cervical) but no increased risk for cancer overall.

However, the reasons for this association between metabolic syndrome and cancer remain unclear, and the effect of the fluctuating nature of metabolic syndrome over time on long-term cancer risk has not been explored, the researchers wrote.
 

What Does New Study Add to Other Research on Metabolic Syndrome and Cancer Risk?

In the new study, published in Cancer on March 11 (doi: 10.1002/cncr.35235), 44,115 adults in China were separated into four trajectories based on metabolic syndrome scores for the period from 2006 to 2010. The scores were based on clinical evidence of metabolic syndrome, defined using the International Diabetes Federation criteria of central obesity and the presence of at least two other factors including increased triglycerides, decreased HDL cholesterol, high blood pressure (or treatment for previously diagnosed hypertension), and increased fasting plasma glucose (or previous diagnosis of type 2 diabetes).

The average age of the participants was 49 years. The four trajectories of metabolic syndrome were low-stable (10.56% of participants), moderate-low (40.84%), moderate-high (41.46%), and elevated-increasing (7.14%), based on trends from the individuals’ initial physical exams on entering the study.

Over a median follow-up period of 9.4 years (from 2010 to 2021), 2,271 cancer diagnoses were reported in the study population. Those with an elevated-increasing metabolic syndrome trajectory had 1.3 times the risk of any cancer compared with those in the low-stable group. Risk for breast cancer, endometrial cancer, kidney cancer, colorectal cancer, and liver cancer in the highest trajectory group were 2.1, 3.3, 4.5, 2.5, and 1.6 times higher, respectively, compared to the lowest group. The increased risk in the elevated-trajectory group for all cancer types persisted when the low-stable, moderate-low, and moderate-high trajectory pattern groups were combined.

The researchers also examined the impact of chronic inflammation and found that individuals with persistently high metabolic syndrome scores and concurrent chronic inflammation had the highest risks of breast, endometrial, colon, and liver cancer. However, individuals with persistently high metabolic syndrome scores and no concurrent chronic inflammation had the highest risk of kidney cancer.
 

 What Are the Limitations of This Research?

The researchers of the current study acknowledged the lack of information on other causes of cancer, including dietary habits, hepatitis C infection, and Helicobacter pylori infection. Other limitations include the focus only on individuals from a single community of mainly middle-aged men in China that may not generalize to other populations.

Also, the metabolic syndrome trajectories did not change much over time, which may be related to the short 4-year study period.
 

What Is the Takeaway Message for Clinical Practice?

The results suggest that monitoring and managing metabolic syndrome could help reduce cancer risk, the researchers concluded. 

“This research suggests that proactive and continuous management of metabolic syndrome may serve as an essential strategy in preventing cancer,” senior author Han-Ping Shi, MD, PhD, of Capital Medical University in Beijing, said in a press release accompanying the study.

More research is needed to assess the impact of these interventions on cancer risk, he noted. However, the data from the current study can guide future research that may lead to more targeted treatments and more effective preventive strategies, he said in a statement.

The study was supported by the National Key Research and Development Program of China. The researchers had no financial conflicts to disclose.

TOPLINE:

The anti-inflammatory shift in mid-pregnancy may be linked to changes in gut microbiota, which, in turn, may wield their influence through fecal and plasma metabolites.

METHODOLOGY:

• Midway through a normal pregnancy, the maternal immune system shifts to a more anti-inflammatory state, which may be linked to changes in the gut microbial community by unknown mechanisms.
• The study explored the associations between the gut microbiota, fecal and plasma metabolites, and cytokine levels of pregnant women and compared them with those of nonpregnant women.
• The study recruited 30 pregnant women (ages 18-34 years; prepregnancy body mass index [BMI], 18.5-21.9) who conceived naturally with a singleton pregnancy and 15 nonpregnant women of similar age and BMI from the First Affiliated Hospital of Jinan University, Guangzhou, China, between February 2019 and August 2020.
• All participants had not used probiotics or antibiotics in the 6 months prior to participating in the study.
• Fecal and blood samples were collected during or after the 37th week of pregnancy in pregnant women until their labor and on the 14th day of the menstrual cycle in nonpregnant women.

TAKEAWAY:

• Pregnant women had more Actinobacteriota than nonpregnant women (9.15% vs 2.98%, respectively; P = .002) in their gut microbiomes, and the most enriched other microbes showed a negative correlation with pro-inflammatory cytokines.
• Pregnant women had differences in 44 fecal and 53 plasma metabolites, with certain enriched metabolites negatively correlated with pro-inflammatory cytokines and certain depleted ones positively correlated.
• Levels of pro-inflammatory plasma cytokines such as interleukins (IL)-1β, IL-2, IL-6, IL-12, interferon gamma, and tumor necrosis factor alpha were reduced, while levels of the anti-inflammatory cytokine IL-4 were elevated in pregnant vs nonpregnant women.
• Researchers identified a total of 46 connections between gut microbes, metabolites, and cytokines, with details suggesting that gut microbes may alter plasma cytokine levels by interacting with host metabolites.

IN PRACTICE:

“Our study revealed complicated associations among gut microbiota, metabolites, and immune system during pregnancy and identified some specific metabolites which may act as mediators between symbiotic microorganisms and immune homeostasis,” the authors wrote.

SOURCE:

The study, led by Ting Huang, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Jinan University, Guangzhou, China, was published online on February 7, 2024, in mSystems.

LIMITATIONS:

The small sample size of the study may have limited capacity to address errors resulting from individual differences. No causal relationships between gut microbiota, metabolites, and immune system response could be confirmed. Researchers were unable to account for the possible effects of confounding variables, such as diet, because of the cross-sectional nature of this study.

DISCLOSURES:

This study was funded by the National Natural Science Foundation of China. The authors declared no conflicts of interest.

A version of this article first appeared on Medscape.com.

TOPLINE:

The anti-inflammatory shift in mid-pregnancy may be linked to changes in gut microbiota, which, in turn, may wield their influence through fecal and plasma metabolites.

METHODOLOGY:

• Midway through a normal pregnancy, the maternal immune system shifts to a more anti-inflammatory state, which may be linked to changes in the gut microbial community by unknown mechanisms.
• The study explored the associations between the gut microbiota, fecal and plasma metabolites, and cytokine levels of pregnant women and compared them with those of nonpregnant women.
• The study recruited 30 pregnant women (ages 18-34 years; prepregnancy body mass index [BMI], 18.5-21.9) who conceived naturally with a singleton pregnancy and 15 nonpregnant women of similar age and BMI from the First Affiliated Hospital of Jinan University, Guangzhou, China, between February 2019 and August 2020.
• All participants had not used probiotics or antibiotics in the 6 months prior to participating in the study.
• Fecal and blood samples were collected during or after the 37th week of pregnancy in pregnant women until their labor and on the 14th day of the menstrual cycle in nonpregnant women.

TAKEAWAY:

• Pregnant women had more Actinobacteriota than nonpregnant women (9.15% vs 2.98%, respectively; P = .002) in their gut microbiomes, and the most enriched other microbes showed a negative correlation with pro-inflammatory cytokines.
• Pregnant women had differences in 44 fecal and 53 plasma metabolites, with certain enriched metabolites negatively correlated with pro-inflammatory cytokines and certain depleted ones positively correlated.
• Levels of pro-inflammatory plasma cytokines such as interleukins (IL)-1β, IL-2, IL-6, IL-12, interferon gamma, and tumor necrosis factor alpha were reduced, while levels of the anti-inflammatory cytokine IL-4 were elevated in pregnant vs nonpregnant women.
• Researchers identified a total of 46 connections between gut microbes, metabolites, and cytokines, with details suggesting that gut microbes may alter plasma cytokine levels by interacting with host metabolites.

IN PRACTICE:

“Our study revealed complicated associations among gut microbiota, metabolites, and immune system during pregnancy and identified some specific metabolites which may act as mediators between symbiotic microorganisms and immune homeostasis,” the authors wrote.

SOURCE:

The study, led by Ting Huang, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Jinan University, Guangzhou, China, was published online on February 7, 2024, in mSystems.

LIMITATIONS:

The small sample size of the study may have limited capacity to address errors resulting from individual differences. No causal relationships between gut microbiota, metabolites, and immune system response could be confirmed. Researchers were unable to account for the possible effects of confounding variables, such as diet, because of the cross-sectional nature of this study.

DISCLOSURES:

This study was funded by the National Natural Science Foundation of China. The authors declared no conflicts of interest.

A version of this article first appeared on Medscape.com.

TOPLINE:

The anti-inflammatory shift in mid-pregnancy may be linked to changes in gut microbiota, which, in turn, may wield their influence through fecal and plasma metabolites.

METHODOLOGY:

• Midway through a normal pregnancy, the maternal immune system shifts to a more anti-inflammatory state, which may be linked to changes in the gut microbial community by unknown mechanisms.
• The study explored the associations between the gut microbiota, fecal and plasma metabolites, and cytokine levels of pregnant women and compared them with those of nonpregnant women.
• The study recruited 30 pregnant women (ages 18-34 years; prepregnancy body mass index [BMI], 18.5-21.9) who conceived naturally with a singleton pregnancy and 15 nonpregnant women of similar age and BMI from the First Affiliated Hospital of Jinan University, Guangzhou, China, between February 2019 and August 2020.
• All participants had not used probiotics or antibiotics in the 6 months prior to participating in the study.
• Fecal and blood samples were collected during or after the 37th week of pregnancy in pregnant women until their labor and on the 14th day of the menstrual cycle in nonpregnant women.

TAKEAWAY:

• Pregnant women had more Actinobacteriota than nonpregnant women (9.15% vs 2.98%, respectively; P = .002) in their gut microbiomes, and the most enriched other microbes showed a negative correlation with pro-inflammatory cytokines.
• Pregnant women had differences in 44 fecal and 53 plasma metabolites, with certain enriched metabolites negatively correlated with pro-inflammatory cytokines and certain depleted ones positively correlated.
• Levels of pro-inflammatory plasma cytokines such as interleukins (IL)-1β, IL-2, IL-6, IL-12, interferon gamma, and tumor necrosis factor alpha were reduced, while levels of the anti-inflammatory cytokine IL-4 were elevated in pregnant vs nonpregnant women.
• Researchers identified a total of 46 connections between gut microbes, metabolites, and cytokines, with details suggesting that gut microbes may alter plasma cytokine levels by interacting with host metabolites.

IN PRACTICE:

“Our study revealed complicated associations among gut microbiota, metabolites, and immune system during pregnancy and identified some specific metabolites which may act as mediators between symbiotic microorganisms and immune homeostasis,” the authors wrote.

SOURCE:

The study, led by Ting Huang, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Jinan University, Guangzhou, China, was published online on February 7, 2024, in mSystems.

LIMITATIONS:

The small sample size of the study may have limited capacity to address errors resulting from individual differences. No causal relationships between gut microbiota, metabolites, and immune system response could be confirmed. Researchers were unable to account for the possible effects of confounding variables, such as diet, because of the cross-sectional nature of this study.

DISCLOSURES:

This study was funded by the National Natural Science Foundation of China. The authors declared no conflicts of interest.

A version of this article first appeared on Medscape.com.

TOPLINE:

A fiber supplement also found in beans and other foods may lead to weight loss and improved insulin sensitivity in people with excess body weight, partly due to changes in the gut microbiota.

METHODOLOGY:

• In animal studies, resistant starch (RS), a kind of dietary fiber, has shown a potential to reduce body fat along with other metabolic benefits, but human dietary studies of RS have been inconsistent, especially with a high-fat diet.
• Researchers conducted a crossover, randomized trial to study the effect of RS as a dietary supplement on 37 individuals with overweight or obesity (average age, 33.43 years; 15 women; body mass index > 24 or higher waist circumference).
• Participants were fed a similar background diet and either 40 g of RS (high-amylose maize) or an energy-matched placebo starch daily for 8 weeks and then switched between the two in a separate 8-week period.
• The primary outcome was body weight, and the secondary outcomes were visceral and subcutaneous fat mass, waist circumference, lipid profiles, insulin sensitivity, metabolome, and gut microbiome.
• RS’s impact on gut microbiota composition and function was assessed with metagenomics and metabolomics, and RS-modified gut microbiota’s effect on host body fat and glucose was confirmed by transferring from select average participants to mice.

TAKEAWAY:

• Participants showed a mean weight loss of 2.8 kg after consuming RS for 8 weeks (P < .001), but there was no significant change in body weight in those on placebo starch.
• RS improved insulin sensitivity in people to a greater extent than placebo starch (P = .025) and showed a greater reduction in fat mass, waist circumference, and other obesity-related outcomes.
• The abundance in the gut of the microbe Bifidobacterium adolescentis increased significantly following RS intervention, an increase that exhibited a strong correlation with decreased BMI, suggesting a role of RS in reducing obesity.
• The levels of pro-inflammatory cytokines, such as serum tumor necrosis factor-alpha and interleukin-1 beta, were significantly lower in participants who consumed RS than in those who had placebo starch.

IN PRACTICE:

“Our study provided an effective dietary recommendation using RS as a supplement (40 g/d with a balanced background diet containing 25%-30% fat), which may help to achieve significant weight loss,” the authors wrote.

SOURCE:

This study was led and corresponded by Huating Li, Shanghai Clinical Center for Diabetes, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China, and University of Hong Kong, Pok Fu Lam, and published online in Nature Metabolism.

LIMITATIONS:

This study was limited by the small sample size and stringent inclusion criteria for participants. The use of database-driven and taxane-based methodology might have led to difficult-to-classify sequences being discarded and strain-level functional diversity being overlooked. The authors also acknowledged the need to validate the findings of this study in larger and more diverse cohorts.

DISCLOSURES:

This work was supported by the National Key Research and Development Program of China, Shanghai Municipal Key Clinical Specialty, National Natural Science Foundation of China, and other sources. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

TOPLINE:

A fiber supplement also found in beans and other foods may lead to weight loss and improved insulin sensitivity in people with excess body weight, partly due to changes in the gut microbiota.

METHODOLOGY:

• In animal studies, resistant starch (RS), a kind of dietary fiber, has shown a potential to reduce body fat along with other metabolic benefits, but human dietary studies of RS have been inconsistent, especially with a high-fat diet.
• Researchers conducted a crossover, randomized trial to study the effect of RS as a dietary supplement on 37 individuals with overweight or obesity (average age, 33.43 years; 15 women; body mass index > 24 or higher waist circumference).
• Participants were fed a similar background diet and either 40 g of RS (high-amylose maize) or an energy-matched placebo starch daily for 8 weeks and then switched between the two in a separate 8-week period.
• The primary outcome was body weight, and the secondary outcomes were visceral and subcutaneous fat mass, waist circumference, lipid profiles, insulin sensitivity, metabolome, and gut microbiome.
• RS’s impact on gut microbiota composition and function was assessed with metagenomics and metabolomics, and RS-modified gut microbiota’s effect on host body fat and glucose was confirmed by transferring from select average participants to mice.

TAKEAWAY:

• Participants showed a mean weight loss of 2.8 kg after consuming RS for 8 weeks (P < .001), but there was no significant change in body weight in those on placebo starch.
• RS improved insulin sensitivity in people to a greater extent than placebo starch (P = .025) and showed a greater reduction in fat mass, waist circumference, and other obesity-related outcomes.
• The abundance in the gut of the microbe Bifidobacterium adolescentis increased significantly following RS intervention, an increase that exhibited a strong correlation with decreased BMI, suggesting a role of RS in reducing obesity.
• The levels of pro-inflammatory cytokines, such as serum tumor necrosis factor-alpha and interleukin-1 beta, were significantly lower in participants who consumed RS than in those who had placebo starch.

IN PRACTICE:

“Our study provided an effective dietary recommendation using RS as a supplement (40 g/d with a balanced background diet containing 25%-30% fat), which may help to achieve significant weight loss,” the authors wrote.

SOURCE:

This study was led and corresponded by Huating Li, Shanghai Clinical Center for Diabetes, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China, and University of Hong Kong, Pok Fu Lam, and published online in Nature Metabolism.

LIMITATIONS:

This study was limited by the small sample size and stringent inclusion criteria for participants. The use of database-driven and taxane-based methodology might have led to difficult-to-classify sequences being discarded and strain-level functional diversity being overlooked. The authors also acknowledged the need to validate the findings of this study in larger and more diverse cohorts.

DISCLOSURES:

This work was supported by the National Key Research and Development Program of China, Shanghai Municipal Key Clinical Specialty, National Natural Science Foundation of China, and other sources. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

TOPLINE:

A fiber supplement also found in beans and other foods may lead to weight loss and improved insulin sensitivity in people with excess body weight, partly due to changes in the gut microbiota.

METHODOLOGY:

• In animal studies, resistant starch (RS), a kind of dietary fiber, has shown a potential to reduce body fat along with other metabolic benefits, but human dietary studies of RS have been inconsistent, especially with a high-fat diet.
• Researchers conducted a crossover, randomized trial to study the effect of RS as a dietary supplement on 37 individuals with overweight or obesity (average age, 33.43 years; 15 women; body mass index > 24 or higher waist circumference).
• Participants were fed a similar background diet and either 40 g of RS (high-amylose maize) or an energy-matched placebo starch daily for 8 weeks and then switched between the two in a separate 8-week period.
• The primary outcome was body weight, and the secondary outcomes were visceral and subcutaneous fat mass, waist circumference, lipid profiles, insulin sensitivity, metabolome, and gut microbiome.
• RS’s impact on gut microbiota composition and function was assessed with metagenomics and metabolomics, and RS-modified gut microbiota’s effect on host body fat and glucose was confirmed by transferring from select average participants to mice.

TAKEAWAY:

• Participants showed a mean weight loss of 2.8 kg after consuming RS for 8 weeks (P < .001), but there was no significant change in body weight in those on placebo starch.
• RS improved insulin sensitivity in people to a greater extent than placebo starch (P = .025) and showed a greater reduction in fat mass, waist circumference, and other obesity-related outcomes.
• The abundance in the gut of the microbe Bifidobacterium adolescentis increased significantly following RS intervention, an increase that exhibited a strong correlation with decreased BMI, suggesting a role of RS in reducing obesity.
• The levels of pro-inflammatory cytokines, such as serum tumor necrosis factor-alpha and interleukin-1 beta, were significantly lower in participants who consumed RS than in those who had placebo starch.

IN PRACTICE:

“Our study provided an effective dietary recommendation using RS as a supplement (40 g/d with a balanced background diet containing 25%-30% fat), which may help to achieve significant weight loss,” the authors wrote.

SOURCE:

This study was led and corresponded by Huating Li, Shanghai Clinical Center for Diabetes, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China, and University of Hong Kong, Pok Fu Lam, and published online in Nature Metabolism.

LIMITATIONS:

This study was limited by the small sample size and stringent inclusion criteria for participants. The use of database-driven and taxane-based methodology might have led to difficult-to-classify sequences being discarded and strain-level functional diversity being overlooked. The authors also acknowledged the need to validate the findings of this study in larger and more diverse cohorts.

DISCLOSURES:

This work was supported by the National Key Research and Development Program of China, Shanghai Municipal Key Clinical Specialty, National Natural Science Foundation of China, and other sources. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

The US Food and Drug Administration (FDA) announced the removal of the endocrine-disrupting chemicals (EDCs) per- and polyfluoroalkyl substances (PFAS) from food packaging.

Issued on February 28, 2024, “this means the major source of dietary exposure to PFAS from food packaging like fast-food wrappers, microwave popcorn bags, take-out paperboard containers, and pet food bags is being eliminated,” the FDA said in a statement.

In 2020, the FDA had secured commitments from manufacturers to stop selling products containing PFAS used in the food packaging for grease-proofing. “Today’s announcement marks the fulfillment of these voluntary commitments,” according to the agency.

PFAS, a class of thousands of chemicals also called “forever chemicals” are widely used in consumer and industrial products. People may be exposed via contaminated food packaging (although perhaps no longer in the United States) or occupationally. Studies have found that some PFAS disrupt hormones including estrogen and testosterone, whereas others may impair thyroid function.
 

Endocrine Society Report Sounds the Alarm About PFAS and Others

The FDA’s announcement came just 2 days after the Endocrine Society issued a new alarm about the human health dangers from environmental EDCs including PFAS in a report covering the latest science.

“Endocrine disrupting chemicals” are individual substances or mixtures that can interfere with natural hormonal function, leading to disease or even death. Many are ubiquitous in the modern environment and contribute to a wide range of human diseases.

The new report Endocrine Disrupting Chemicals: Threats to Human Health was issued jointly with the International Pollutants Elimination Network (IPEN), a global advocacy organization. It’s an update to the Endocrine Society’s 2015 report, providing new data on the endocrine-disrupting substances previously covered and adding four EDCs not discussed in that document: Pesticides, plastics, PFAS, and children’s products containing arsenic.

At a briefing held during the United Nations Environment Assembly meeting in Nairobi, Kenya, last week, the new report’s lead author Andrea C. Gore, PhD, of the University of Texas at Austin, noted, “A well-established body of scientific research indicates that endocrine-disrupting chemicals that are part of our daily lives are making us more susceptible to reproductive disorders, cancer, diabetes, obesity, heart disease, and other serious health conditions.”

Added Dr. Gore, who is also a member of the Endocrine Society’s Board of Directors, “These chemicals pose particularly serious risks to pregnant women and children. Now is the time for the UN Environment Assembly and other global policymakers to take action to address this threat to public health.”

While the science has been emerging rapidly, global and national chemical control policies haven’t kept up, the authors said. Of particular concern is that EDCs behave differently from other chemicals in many ways, including that even very low-dose exposures can pose health threats, but policies thus far haven’t dealt with that aspect.

Moreover, “the effects of low doses cannot be predicted by the effects observed at high doses. This means there may be no safe dose for exposure to EDCs,” according to the report.

Exposures can come from household products, including furniture, toys, and food packages, as well as electronics building materials and cosmetics. These chemicals are also in the outdoor environment, via pesticides, air pollution, and industrial waste.

“IPEN and the Endocrine Society call for chemical regulations based on the most modern scientific understanding of how hormones act and how EDCs can perturb these actions. We work to educate policy makers in global, regional, and national government assemblies and help ensure that regulations correlate with current scientific understanding,” they said in the report.
 

New Data on Four Classes of EDCs

Chapters of the report summarized the latest information about the science of EDCs and their links to endocrine disease and real-world exposure. It included a special section about “EDCs throughout the plastics life cycle” and a summary of the links between EDCs and climate change.

The report reviewed three pesticides, including the world’s most heavily applied herbicide, glycophosphate. Exposures can occur directly from the air, water, dust, and food residues. Recent data linked glycophosphate to adverse reproductive health outcomes.

Two toxic plastic chemicals, phthalates and bisphenols, are present in personal care products, among others. Emerging evidence links them with impaired neurodevelopment, leading to impaired cognitive function, learning, attention, and impulsivity.

Arsenic has long been linked to human health conditions including cancer, but more recent evidence finds it can disrupt multiple endocrine systems and lead to metabolic conditions including diabetes, reproductive dysfunction, and cardiovascular and neurocognitive conditions.

The special section about plastics noted that they are made from fossil fuels and chemicals, including many toxic substances that are known or suspected EDCs. People who live near plastic production facilities or waste dumps may be at greatest risk, but anyone can be exposed using any plastic product. Plastic waste disposal is increasingly problematic and often foisted on lower- and middle-income countries.
 

‘Additional Education and Awareness-Raising Among Stakeholders Remain Necessary’

Policies aimed at reducing human health risks from EDCs have included the 2022 Plastics Treaty, a resolution adopted by 175 countries at the United Nations Environmental Assembly that “may be a significant step toward global control of plastics and elimination of threats from exposures to EDCs in plastics,” the report said.

The authors added, “While significant progress has been made in recent years connecting scientific advances on EDCs with health-protective policies, additional education and awareness-raising among stakeholders remain necessary to achieve a safer and more sustainable environment that minimizes exposure to these harmful chemicals.”

The document was produced with financial contributions from the Government of Sweden, the Tides Foundation, Passport Foundation, and other donors.

A version of this article appeared on Medscape.com.

The US Food and Drug Administration (FDA) announced the removal of the endocrine-disrupting chemicals (EDCs) per- and polyfluoroalkyl substances (PFAS) from food packaging.

Issued on February 28, 2024, “this means the major source of dietary exposure to PFAS from food packaging like fast-food wrappers, microwave popcorn bags, take-out paperboard containers, and pet food bags is being eliminated,” the FDA said in a statement.

In 2020, the FDA had secured commitments from manufacturers to stop selling products containing PFAS used in the food packaging for grease-proofing. “Today’s announcement marks the fulfillment of these voluntary commitments,” according to the agency.

PFAS, a class of thousands of chemicals also called “forever chemicals” are widely used in consumer and industrial products. People may be exposed via contaminated food packaging (although perhaps no longer in the United States) or occupationally. Studies have found that some PFAS disrupt hormones including estrogen and testosterone, whereas others may impair thyroid function.
 

Endocrine Society Report Sounds the Alarm About PFAS and Others

The FDA’s announcement came just 2 days after the Endocrine Society issued a new alarm about the human health dangers from environmental EDCs including PFAS in a report covering the latest science.

“Endocrine disrupting chemicals” are individual substances or mixtures that can interfere with natural hormonal function, leading to disease or even death. Many are ubiquitous in the modern environment and contribute to a wide range of human diseases.

The new report Endocrine Disrupting Chemicals: Threats to Human Health was issued jointly with the International Pollutants Elimination Network (IPEN), a global advocacy organization. It’s an update to the Endocrine Society’s 2015 report, providing new data on the endocrine-disrupting substances previously covered and adding four EDCs not discussed in that document: Pesticides, plastics, PFAS, and children’s products containing arsenic.

At a briefing held during the United Nations Environment Assembly meeting in Nairobi, Kenya, last week, the new report’s lead author Andrea C. Gore, PhD, of the University of Texas at Austin, noted, “A well-established body of scientific research indicates that endocrine-disrupting chemicals that are part of our daily lives are making us more susceptible to reproductive disorders, cancer, diabetes, obesity, heart disease, and other serious health conditions.”

Added Dr. Gore, who is also a member of the Endocrine Society’s Board of Directors, “These chemicals pose particularly serious risks to pregnant women and children. Now is the time for the UN Environment Assembly and other global policymakers to take action to address this threat to public health.”

While the science has been emerging rapidly, global and national chemical control policies haven’t kept up, the authors said. Of particular concern is that EDCs behave differently from other chemicals in many ways, including that even very low-dose exposures can pose health threats, but policies thus far haven’t dealt with that aspect.

Moreover, “the effects of low doses cannot be predicted by the effects observed at high doses. This means there may be no safe dose for exposure to EDCs,” according to the report.

Exposures can come from household products, including furniture, toys, and food packages, as well as electronics building materials and cosmetics. These chemicals are also in the outdoor environment, via pesticides, air pollution, and industrial waste.

“IPEN and the Endocrine Society call for chemical regulations based on the most modern scientific understanding of how hormones act and how EDCs can perturb these actions. We work to educate policy makers in global, regional, and national government assemblies and help ensure that regulations correlate with current scientific understanding,” they said in the report.
 

New Data on Four Classes of EDCs

Chapters of the report summarized the latest information about the science of EDCs and their links to endocrine disease and real-world exposure. It included a special section about “EDCs throughout the plastics life cycle” and a summary of the links between EDCs and climate change.

The report reviewed three pesticides, including the world’s most heavily applied herbicide, glycophosphate. Exposures can occur directly from the air, water, dust, and food residues. Recent data linked glycophosphate to adverse reproductive health outcomes.

Two toxic plastic chemicals, phthalates and bisphenols, are present in personal care products, among others. Emerging evidence links them with impaired neurodevelopment, leading to impaired cognitive function, learning, attention, and impulsivity.

Arsenic has long been linked to human health conditions including cancer, but more recent evidence finds it can disrupt multiple endocrine systems and lead to metabolic conditions including diabetes, reproductive dysfunction, and cardiovascular and neurocognitive conditions.

The special section about plastics noted that they are made from fossil fuels and chemicals, including many toxic substances that are known or suspected EDCs. People who live near plastic production facilities or waste dumps may be at greatest risk, but anyone can be exposed using any plastic product. Plastic waste disposal is increasingly problematic and often foisted on lower- and middle-income countries.
 

‘Additional Education and Awareness-Raising Among Stakeholders Remain Necessary’

Policies aimed at reducing human health risks from EDCs have included the 2022 Plastics Treaty, a resolution adopted by 175 countries at the United Nations Environmental Assembly that “may be a significant step toward global control of plastics and elimination of threats from exposures to EDCs in plastics,” the report said.

The authors added, “While significant progress has been made in recent years connecting scientific advances on EDCs with health-protective policies, additional education and awareness-raising among stakeholders remain necessary to achieve a safer and more sustainable environment that minimizes exposure to these harmful chemicals.”

The document was produced with financial contributions from the Government of Sweden, the Tides Foundation, Passport Foundation, and other donors.

A version of this article appeared on Medscape.com.

The US Food and Drug Administration (FDA) announced the removal of the endocrine-disrupting chemicals (EDCs) per- and polyfluoroalkyl substances (PFAS) from food packaging.

Issued on February 28, 2024, “this means the major source of dietary exposure to PFAS from food packaging like fast-food wrappers, microwave popcorn bags, take-out paperboard containers, and pet food bags is being eliminated,” the FDA said in a statement.

In 2020, the FDA had secured commitments from manufacturers to stop selling products containing PFAS used in the food packaging for grease-proofing. “Today’s announcement marks the fulfillment of these voluntary commitments,” according to the agency.

PFAS, a class of thousands of chemicals also called “forever chemicals” are widely used in consumer and industrial products. People may be exposed via contaminated food packaging (although perhaps no longer in the United States) or occupationally. Studies have found that some PFAS disrupt hormones including estrogen and testosterone, whereas others may impair thyroid function.
 

Endocrine Society Report Sounds the Alarm About PFAS and Others

The FDA’s announcement came just 2 days after the Endocrine Society issued a new alarm about the human health dangers from environmental EDCs including PFAS in a report covering the latest science.

“Endocrine disrupting chemicals” are individual substances or mixtures that can interfere with natural hormonal function, leading to disease or even death. Many are ubiquitous in the modern environment and contribute to a wide range of human diseases.

The new report Endocrine Disrupting Chemicals: Threats to Human Health was issued jointly with the International Pollutants Elimination Network (IPEN), a global advocacy organization. It’s an update to the Endocrine Society’s 2015 report, providing new data on the endocrine-disrupting substances previously covered and adding four EDCs not discussed in that document: Pesticides, plastics, PFAS, and children’s products containing arsenic.

At a briefing held during the United Nations Environment Assembly meeting in Nairobi, Kenya, last week, the new report’s lead author Andrea C. Gore, PhD, of the University of Texas at Austin, noted, “A well-established body of scientific research indicates that endocrine-disrupting chemicals that are part of our daily lives are making us more susceptible to reproductive disorders, cancer, diabetes, obesity, heart disease, and other serious health conditions.”

Added Dr. Gore, who is also a member of the Endocrine Society’s Board of Directors, “These chemicals pose particularly serious risks to pregnant women and children. Now is the time for the UN Environment Assembly and other global policymakers to take action to address this threat to public health.”

While the science has been emerging rapidly, global and national chemical control policies haven’t kept up, the authors said. Of particular concern is that EDCs behave differently from other chemicals in many ways, including that even very low-dose exposures can pose health threats, but policies thus far haven’t dealt with that aspect.

Moreover, “the effects of low doses cannot be predicted by the effects observed at high doses. This means there may be no safe dose for exposure to EDCs,” according to the report.

Exposures can come from household products, including furniture, toys, and food packages, as well as electronics building materials and cosmetics. These chemicals are also in the outdoor environment, via pesticides, air pollution, and industrial waste.

“IPEN and the Endocrine Society call for chemical regulations based on the most modern scientific understanding of how hormones act and how EDCs can perturb these actions. We work to educate policy makers in global, regional, and national government assemblies and help ensure that regulations correlate with current scientific understanding,” they said in the report.
 

New Data on Four Classes of EDCs

Chapters of the report summarized the latest information about the science of EDCs and their links to endocrine disease and real-world exposure. It included a special section about “EDCs throughout the plastics life cycle” and a summary of the links between EDCs and climate change.

The report reviewed three pesticides, including the world’s most heavily applied herbicide, glycophosphate. Exposures can occur directly from the air, water, dust, and food residues. Recent data linked glycophosphate to adverse reproductive health outcomes.

Two toxic plastic chemicals, phthalates and bisphenols, are present in personal care products, among others. Emerging evidence links them with impaired neurodevelopment, leading to impaired cognitive function, learning, attention, and impulsivity.

Arsenic has long been linked to human health conditions including cancer, but more recent evidence finds it can disrupt multiple endocrine systems and lead to metabolic conditions including diabetes, reproductive dysfunction, and cardiovascular and neurocognitive conditions.

The special section about plastics noted that they are made from fossil fuels and chemicals, including many toxic substances that are known or suspected EDCs. People who live near plastic production facilities or waste dumps may be at greatest risk, but anyone can be exposed using any plastic product. Plastic waste disposal is increasingly problematic and often foisted on lower- and middle-income countries.
 

‘Additional Education and Awareness-Raising Among Stakeholders Remain Necessary’

Policies aimed at reducing human health risks from EDCs have included the 2022 Plastics Treaty, a resolution adopted by 175 countries at the United Nations Environmental Assembly that “may be a significant step toward global control of plastics and elimination of threats from exposures to EDCs in plastics,” the report said.

The authors added, “While significant progress has been made in recent years connecting scientific advances on EDCs with health-protective policies, additional education and awareness-raising among stakeholders remain necessary to achieve a safer and more sustainable environment that minimizes exposure to these harmful chemicals.”

The document was produced with financial contributions from the Government of Sweden, the Tides Foundation, Passport Foundation, and other donors.

A version of this article appeared on Medscape.com.

Bariatric surgery appears to decrease the risk for some cancers, but it may increase the risk for others, particularly colorectal cancer (CRC), according to a synthesis of current evidence.

“There has been a recent burst of studies examining the association between bariatric surgery and the longitudinal risks of developing cancer,” corresponding author Zhi Ven Fong, MD, MPH, DrPH, surgical oncologist, Mayo Clinic Arizona, Phoenix, said in an interview. “However, there has not been a rigorous and critical analysis of the data published to date.”

In evaluating research showing an association between bariatric surgery and longitudinal cancer risk, the investigators found that the quality of the studies and their findings are “heterogeneous and might be susceptible to bias,” Dr. Fong said.

Bariatric surgery appears to have the strongest and most consistent association with the reduction of breast, ovarian, and endometrial cancer risk, first author Pei-Wen Lim, MD, MS, bariatric surgeon at Mayo Clinic Arizona, Phoenix, told this news organization. “However, there have been concerning signals from preclinical and epidemiological studies that bariatric surgery may be associated with a higher risk of developing colorectal cancers,” she added.

The authors cautioned against certain changes in clinical management.

“First, cancer surveillance frequency should not be altered after bariatric surgery because of any assumed reduction in longitudinal cancer risk, and surveillance strategy should mirror that of an average-risk individual,” they wrote. “Secondly, the indications for bariatric surgery should not be expanded for the purpose of cancer-risk mitigation.”

The review was published online in JAMA Surgery.
 

Protection Against Hormone-Related Cancers

The authors pointed to several studies that appear to support the association between bariatric surgery and decreased risk for hormone-related cancers.

Among them is an observational study of 6781 patients in Canada that showed a significant reduction in breast cancer risk at a median follow-up of 5 years in those who had bariatric surgery vs those who did not (P = .01).

The largest study to date on risk for hormone-related cancer after bariatric surgery was conducted using New York State data for 302,883 women.

It showed a lower rate of breast, endometrial, and ovarian cancers after bariatric surgery (hazard ratio [HR], 0.78; P < .001), with Roux-en-Y gastric bypass conferring the greatest benefit compared with laparoscopic sleeve gastrectomy (HR, 0.66; P = .006) and laparoscopic adjustable gastric banding (HR, 0.83; P = .006).

Beyond the shared mechanisms explaining obesity and cancer risk, a proposed explanation for the strong, consistent association between bariatric surgery and hormone-sensitive cancers is the role obesity-related changes in estrogen stimulation play in development of such cancers, the authors noted.
 

Association With GI Cancers

The association between bariatric surgery and development of esophageal, gastric, liver, and pancreas cancers is less clear. The data are heterogeneous, with studies showing either no association or decreased longitudinal incidence, the authors reported.

The data are also mixed when it comes to CRC. Epidemiological studies have demonstrated decreased longitudinal incidence of colon and rectal cancer after bariatric surgery; however, two studies have suggested an increased CRC risk after bariatric surgery, the authors noted.

A 15-year study from England that matched 8794 patients with obesity who underwent bariatric surgery with 8794 patients with obesity who did not have the surgery showed that gastric bypass (but not gastric banding or sleeve gastrectomy) was associated with a greater than twofold increased risk of developing colon and rectal cancer (odds ratio, 2.63).

These findings were corroborated in a Swedish cohort study with more than 10 years of follow-up data.

One potential explanation for the heterogeneous findings is that “present studies do not discriminate the sub-types of colon and rectal cancer, with bariatric surgery possibly increasing the incidence of colitis-associated cancers but not hereditary cancers,” the authors wrote.

“The mechanism by which gastric bypass may increase the risk of colorectal cancer is through changes in the gut’s microbiome. These changes in gut flora may triumph the protective effect of weight loss on the development of colorectal cancers,” Dr. Fong said.

Prospective studies are necessary to better delineate CRC risk after bariatric surgery, the authors wrote.
 

Benefits Outweigh Risk

“Ultimately, it has been proven that bariatric surgery saves lives by improving the metabolic profile of patients with obesity through reduction in cardiovascular risk factors such as hypertension, diabetes, and nonalcoholic fatty liver disease,” Dr. Lim said.

“If patients qualify for bariatric surgery on the basis of their BMI or comorbidities, they should pursue it for its metabolic benefits, but perhaps consider timely or closer-interval screening colonoscopies to monitor for potential colorectal cancer development,” Dr. Lim added.

When asked to comment on the review, Marina Kurian, MD, president, American Society for Metabolic and Bariatric Surgery, also pointed to the advantages of bariatric surgery in reducing major adverse cardiovascular events and improving hypertension, hyperlipidemia, and diabetes.

Bariatric surgery reduces many types of cancers, although the data specific to CRC risk with bariatric surgery are mixed, she added.

“The jury is still out,” said Dr. Kurian, clinical professor of surgery at NYU Langone Health in New York, who was not involved in the review. “There are papers and meta-analyses that show benefit even in colorectal cancer, but then there are a couple of papers out there that suggest a risk that seems to be specific to men.

“It could just be a numbers game, where we may not have enough data. We need more granular data that will help address these nuances and really determine what is the actual risk,” Dr. Kurian said. “But overall, for cancer, bariatric surgery is a win.”

This research had no specific funding. Dr. Fong and Dr. Lim had no relevant disclosures. Dr. Kurian disclosed relationships with Allergan, Allurion, CineMed, CSATS, Ezisurg Medical, Hernon, Johnson & Johnson, Medtronic, Novo, Stryker, and Vivus.
 

A version of this article appeared on Medscape.com.

Bariatric surgery appears to decrease the risk for some cancers, but it may increase the risk for others, particularly colorectal cancer (CRC), according to a synthesis of current evidence.

“There has been a recent burst of studies examining the association between bariatric surgery and the longitudinal risks of developing cancer,” corresponding author Zhi Ven Fong, MD, MPH, DrPH, surgical oncologist, Mayo Clinic Arizona, Phoenix, said in an interview. “However, there has not been a rigorous and critical analysis of the data published to date.”

In evaluating research showing an association between bariatric surgery and longitudinal cancer risk, the investigators found that the quality of the studies and their findings are “heterogeneous and might be susceptible to bias,” Dr. Fong said.

Bariatric surgery appears to have the strongest and most consistent association with the reduction of breast, ovarian, and endometrial cancer risk, first author Pei-Wen Lim, MD, MS, bariatric surgeon at Mayo Clinic Arizona, Phoenix, told this news organization. “However, there have been concerning signals from preclinical and epidemiological studies that bariatric surgery may be associated with a higher risk of developing colorectal cancers,” she added.

The authors cautioned against certain changes in clinical management.

“First, cancer surveillance frequency should not be altered after bariatric surgery because of any assumed reduction in longitudinal cancer risk, and surveillance strategy should mirror that of an average-risk individual,” they wrote. “Secondly, the indications for bariatric surgery should not be expanded for the purpose of cancer-risk mitigation.”

The review was published online in JAMA Surgery.
 

Protection Against Hormone-Related Cancers

The authors pointed to several studies that appear to support the association between bariatric surgery and decreased risk for hormone-related cancers.

Among them is an observational study of 6781 patients in Canada that showed a significant reduction in breast cancer risk at a median follow-up of 5 years in those who had bariatric surgery vs those who did not (P = .01).

The largest study to date on risk for hormone-related cancer after bariatric surgery was conducted using New York State data for 302,883 women.

It showed a lower rate of breast, endometrial, and ovarian cancers after bariatric surgery (hazard ratio [HR], 0.78; P < .001), with Roux-en-Y gastric bypass conferring the greatest benefit compared with laparoscopic sleeve gastrectomy (HR, 0.66; P = .006) and laparoscopic adjustable gastric banding (HR, 0.83; P = .006).

Beyond the shared mechanisms explaining obesity and cancer risk, a proposed explanation for the strong, consistent association between bariatric surgery and hormone-sensitive cancers is the role obesity-related changes in estrogen stimulation play in development of such cancers, the authors noted.
 

Association With GI Cancers

The association between bariatric surgery and development of esophageal, gastric, liver, and pancreas cancers is less clear. The data are heterogeneous, with studies showing either no association or decreased longitudinal incidence, the authors reported.

The data are also mixed when it comes to CRC. Epidemiological studies have demonstrated decreased longitudinal incidence of colon and rectal cancer after bariatric surgery; however, two studies have suggested an increased CRC risk after bariatric surgery, the authors noted.

A 15-year study from England that matched 8794 patients with obesity who underwent bariatric surgery with 8794 patients with obesity who did not have the surgery showed that gastric bypass (but not gastric banding or sleeve gastrectomy) was associated with a greater than twofold increased risk of developing colon and rectal cancer (odds ratio, 2.63).

These findings were corroborated in a Swedish cohort study with more than 10 years of follow-up data.

One potential explanation for the heterogeneous findings is that “present studies do not discriminate the sub-types of colon and rectal cancer, with bariatric surgery possibly increasing the incidence of colitis-associated cancers but not hereditary cancers,” the authors wrote.

“The mechanism by which gastric bypass may increase the risk of colorectal cancer is through changes in the gut’s microbiome. These changes in gut flora may triumph the protective effect of weight loss on the development of colorectal cancers,” Dr. Fong said.

Prospective studies are necessary to better delineate CRC risk after bariatric surgery, the authors wrote.
 

Benefits Outweigh Risk

“Ultimately, it has been proven that bariatric surgery saves lives by improving the metabolic profile of patients with obesity through reduction in cardiovascular risk factors such as hypertension, diabetes, and nonalcoholic fatty liver disease,” Dr. Lim said.

“If patients qualify for bariatric surgery on the basis of their BMI or comorbidities, they should pursue it for its metabolic benefits, but perhaps consider timely or closer-interval screening colonoscopies to monitor for potential colorectal cancer development,” Dr. Lim added.

When asked to comment on the review, Marina Kurian, MD, president, American Society for Metabolic and Bariatric Surgery, also pointed to the advantages of bariatric surgery in reducing major adverse cardiovascular events and improving hypertension, hyperlipidemia, and diabetes.

Bariatric surgery reduces many types of cancers, although the data specific to CRC risk with bariatric surgery are mixed, she added.

“The jury is still out,” said Dr. Kurian, clinical professor of surgery at NYU Langone Health in New York, who was not involved in the review. “There are papers and meta-analyses that show benefit even in colorectal cancer, but then there are a couple of papers out there that suggest a risk that seems to be specific to men.

“It could just be a numbers game, where we may not have enough data. We need more granular data that will help address these nuances and really determine what is the actual risk,” Dr. Kurian said. “But overall, for cancer, bariatric surgery is a win.”

This research had no specific funding. Dr. Fong and Dr. Lim had no relevant disclosures. Dr. Kurian disclosed relationships with Allergan, Allurion, CineMed, CSATS, Ezisurg Medical, Hernon, Johnson & Johnson, Medtronic, Novo, Stryker, and Vivus.
 

A version of this article appeared on Medscape.com.

Bariatric surgery appears to decrease the risk for some cancers, but it may increase the risk for others, particularly colorectal cancer (CRC), according to a synthesis of current evidence.

“There has been a recent burst of studies examining the association between bariatric surgery and the longitudinal risks of developing cancer,” corresponding author Zhi Ven Fong, MD, MPH, DrPH, surgical oncologist, Mayo Clinic Arizona, Phoenix, said in an interview. “However, there has not been a rigorous and critical analysis of the data published to date.”

In evaluating research showing an association between bariatric surgery and longitudinal cancer risk, the investigators found that the quality of the studies and their findings are “heterogeneous and might be susceptible to bias,” Dr. Fong said.

Bariatric surgery appears to have the strongest and most consistent association with the reduction of breast, ovarian, and endometrial cancer risk, first author Pei-Wen Lim, MD, MS, bariatric surgeon at Mayo Clinic Arizona, Phoenix, told this news organization. “However, there have been concerning signals from preclinical and epidemiological studies that bariatric surgery may be associated with a higher risk of developing colorectal cancers,” she added.

The authors cautioned against certain changes in clinical management.

“First, cancer surveillance frequency should not be altered after bariatric surgery because of any assumed reduction in longitudinal cancer risk, and surveillance strategy should mirror that of an average-risk individual,” they wrote. “Secondly, the indications for bariatric surgery should not be expanded for the purpose of cancer-risk mitigation.”

The review was published online in JAMA Surgery.
 

Protection Against Hormone-Related Cancers

The authors pointed to several studies that appear to support the association between bariatric surgery and decreased risk for hormone-related cancers.

Among them is an observational study of 6781 patients in Canada that showed a significant reduction in breast cancer risk at a median follow-up of 5 years in those who had bariatric surgery vs those who did not (P = .01).

The largest study to date on risk for hormone-related cancer after bariatric surgery was conducted using New York State data for 302,883 women.

It showed a lower rate of breast, endometrial, and ovarian cancers after bariatric surgery (hazard ratio [HR], 0.78; P < .001), with Roux-en-Y gastric bypass conferring the greatest benefit compared with laparoscopic sleeve gastrectomy (HR, 0.66; P = .006) and laparoscopic adjustable gastric banding (HR, 0.83; P = .006).

Beyond the shared mechanisms explaining obesity and cancer risk, a proposed explanation for the strong, consistent association between bariatric surgery and hormone-sensitive cancers is the role obesity-related changes in estrogen stimulation play in development of such cancers, the authors noted.
 

Association With GI Cancers

The association between bariatric surgery and development of esophageal, gastric, liver, and pancreas cancers is less clear. The data are heterogeneous, with studies showing either no association or decreased longitudinal incidence, the authors reported.

The data are also mixed when it comes to CRC. Epidemiological studies have demonstrated decreased longitudinal incidence of colon and rectal cancer after bariatric surgery; however, two studies have suggested an increased CRC risk after bariatric surgery, the authors noted.

A 15-year study from England that matched 8794 patients with obesity who underwent bariatric surgery with 8794 patients with obesity who did not have the surgery showed that gastric bypass (but not gastric banding or sleeve gastrectomy) was associated with a greater than twofold increased risk of developing colon and rectal cancer (odds ratio, 2.63).

These findings were corroborated in a Swedish cohort study with more than 10 years of follow-up data.

One potential explanation for the heterogeneous findings is that “present studies do not discriminate the sub-types of colon and rectal cancer, with bariatric surgery possibly increasing the incidence of colitis-associated cancers but not hereditary cancers,” the authors wrote.

“The mechanism by which gastric bypass may increase the risk of colorectal cancer is through changes in the gut’s microbiome. These changes in gut flora may triumph the protective effect of weight loss on the development of colorectal cancers,” Dr. Fong said.

Prospective studies are necessary to better delineate CRC risk after bariatric surgery, the authors wrote.
 

Benefits Outweigh Risk

“Ultimately, it has been proven that bariatric surgery saves lives by improving the metabolic profile of patients with obesity through reduction in cardiovascular risk factors such as hypertension, diabetes, and nonalcoholic fatty liver disease,” Dr. Lim said.

“If patients qualify for bariatric surgery on the basis of their BMI or comorbidities, they should pursue it for its metabolic benefits, but perhaps consider timely or closer-interval screening colonoscopies to monitor for potential colorectal cancer development,” Dr. Lim added.

When asked to comment on the review, Marina Kurian, MD, president, American Society for Metabolic and Bariatric Surgery, also pointed to the advantages of bariatric surgery in reducing major adverse cardiovascular events and improving hypertension, hyperlipidemia, and diabetes.

Bariatric surgery reduces many types of cancers, although the data specific to CRC risk with bariatric surgery are mixed, she added.

“The jury is still out,” said Dr. Kurian, clinical professor of surgery at NYU Langone Health in New York, who was not involved in the review. “There are papers and meta-analyses that show benefit even in colorectal cancer, but then there are a couple of papers out there that suggest a risk that seems to be specific to men.

“It could just be a numbers game, where we may not have enough data. We need more granular data that will help address these nuances and really determine what is the actual risk,” Dr. Kurian said. “But overall, for cancer, bariatric surgery is a win.”

This research had no specific funding. Dr. Fong and Dr. Lim had no relevant disclosures. Dr. Kurian disclosed relationships with Allergan, Allurion, CineMed, CSATS, Ezisurg Medical, Hernon, Johnson & Johnson, Medtronic, Novo, Stryker, and Vivus.
 

A version of this article appeared on Medscape.com.

The explosion of interest in glucagon-like peptide 1 receptor agonists (GLP-1 RAs), such as semaglutide and tirzepatide, has raised questions about what therapeutic effects this class of medication might have beyond their current indications for type 2 diabetes and obesity. 

Recent clinical trials have recently identified benefits from GLP-1 agents for the heart, liver, and kidneys, but the current evidence base is murkier regarding how the drugs may affect male fertility. 

Experts say the connection between GLP-1 RAs and improved male fertility makes sense biologically. For starters, overweight and obesity are strongly associated with male infertility in several overlapping ways. Obesity can disrupt hormones linked to fertility, increase the risk for defective sperm, adversely affect semen quality, and even make sexual intercourse more difficult due to obesity’s link to erectile dysfunction. As a result, GLP-1 RAs should at least in theory boost male fertility in men who take the drugs to lose weight. 

But animal studies and a handful of small trials and observational data point to the potential for GLP-1 RAs to improve male fertility in other ways.

A recent narrative review on GLP-1 RAs and male reproductive health, published in the journal Medicina in December 2023, surveyed the potential of the drugs for male infertility and offered reason for optimism. 

Hossein Sadeghi-Nejad, MD, director of urology at NYU Langone Health, New York, and a coauthor of the article, said that one reason he and his colleagues conducted their analysis was the known association between weight loss and an increase in testosterone.

“Most of the animal studies that are out there show that this class of drugs does affect testosterone levels,” Dr. Sadeghi-Nejad said; they wanted to better understand what other evidence showed about GLP-1 agonists and other fertility factors. 
 

Link Between Obesity and Fertility

The recent paper first reviews the well-established link between obesity and poorer fertility outcomes. 

“Certainly, obesity poses a significant societal problem with substantial impacts on both overall health and economic aspects,” senior author Ranjith Ramasamy, MD, associate professor of urology and director of the reproductive urology Fellowship program at the University of Miami’s Miller School of Medicine, told this news organization. “The escalating global obesity rates raise concerns, especially in the field of male infertility, where excessive body fat induces intrinsic hormonal changes leading to alterations, eventually, in semen parameters.”

The authors noted that obesity has been linked in the research to worse assisted reproductive technology (ART) outcomes and to subfecundity, taking more than 12 months to achieve pregnancy. They also referenced a systematic review that found men with obesity were more likely to have lower sperm counts and less viable sperm.

“From our standpoint, I think the key point was to raise awareness about the fact that obesity, because of the aromatization of testosterone to estradiol [from excess adipose tissue], will affect the hormonal axis and the availability of testosterone and, therefore, indirectly affects spermatogenesis,” Dr. Sadeghi-Nejad said. 

Obesity is also linked to lower levels of inhibin B, which stimulates testosterone secretion in Sertoli cells, which, when combined with the proinflammatory state of obesity, “results in a less favorable environment for sperm production,” he said. Finally, the link between obesity and poorer sexual function further inhibits fertility potential, he added. 

Until recently, the primary treatments for obesity in men experiencing fertility problems have been lifestyle modifications or surgical interventions. But the recent approval of GLP-1 RA drugs for obesity present an additional option depending on how these drugs affect other fertility parameters. 
 

Direct or Indirect Effects?

Most of the available evidence on GLP-RAs and sperm parameters comes from preclinical research. One of the few clinical trials, published last year in the Journal of Clinical Medicine, investigated the effects of liraglutide in men with metabolic hypogonadism, a body mass index between (BMI) 30 and 40, and severe erectile dysfunction. 

Among the 110 men enrolled in the study, only the 35 participants who said that they were not seeking fatherhood received liraglutide. After 4 months of treatment, these men had significantly improved semen concentration, motility, and morphology than did those wanting to conceive who received conventional fertility treatment. Erectile dysfunction was also more improved in the liraglutide group, according to the researchers. 

Though this study demonstrated the potential for liraglutide to treat metabolic hypogonadism, the men in that group also had greater weight loss and BMI reduction than the other participants. The review cited several other studies — albeit small ones — in which weight loss was associated with improvements in sperm parameters, including one randomized controlled trial in which one group lost weight with liraglutide and the other with lifestyle modifications; both groups showed increases in the concentration and number of sperm. 

One of the key questions requiring further research, then, is whether GLP-1 agents have direct effects on male fertility independent of a reduction in obesity. The randomized controlled trials comparing liraglutide and lifestyle modifications failed to find additional effects on semen in the men taking liraglutide; however, the study had only 56 participants, and results from liraglutide cannot be generalized to potential effects of semaglutide or tirzepatide, Dr. Sadeghi-Nejad said.

“Determining the relative contributions of weight loss versus direct drug actions on fertility outcomes remains challenging without robust data,” Dr. Ramasamy said. “While acknowledged that diet and physical activity positively impact fertility, confirming the synergistic role of GLP-1 receptor agonists requires evidence from well-designed randomized clinical trials.” 

Rodent studies suggest that GLP-1 RAs may independently affect testicular function because GLP-1 receptors exist in Sertoli and Leydig cells of the testes. In one study, for example, obese mice who received the GLP-1 agonist exenatide for 8 weeks had “improved sperm motility, DNA integrity, and decreased expression of pro-inflammatory cytokines,” the authors of the review reported. But the precise mechanisms aren’t well understood. 

“We know that there are GLP-1 receptors in the reproductive tract, but the extent of the downstream effect of stimulating those receptors, I don’t think we know well,” said John P. Lindsey II, MD, MEng, assistant professor of urology at University of California San Francisco Health. 

Other hormonal effects of GLP-1 agonists, such as stimulating insulin production and better regulating blood glucose levels, are better understood, said Raevti Bole, MD, a urologist at Cleveland Clinic, in Ohio, but still other effects of the drugs may not yet be identified.

“I think the really big unknown is whether these types of drugs have effects that are not hormonal on male fertility and what those effects are, and how those affect sperm,” Dr. Bole said. “For example, we know that these drugs slow gastric emptying. Is it possible that slow gastric emptying affects some of the nutrients that you absorb, and that could affect fertility?” Similarly, she said, it’s not clear whether GLP-1 agonists would have any effects on the thyroid that could then affect fertility. 
 

Effects on Offspring

Another open question about GLP-1 RAs and male fertility is their potential effects on the offspring, said Sriram Machineni, MBBS, associate professor of endocrinology at the Albert Einstein College of Medicine in New York City. The clinical trials involving the drugs for treating type 2 diabetes and obesity required both men and women to use contraception. If sperm contributing to a pregnancy are exposed to a GLP-1 agent, “we don’t know what the consequences could be,” Dr. Machineni said. “Just increasing the fertility of the man is not enough. We need to make sure it’s safe long-term for the fetus.”

Dr. Bole also pointed out the need for understanding potential effects in the fetus.

“We know that there are epigenetic changes that can happen to sperm that are influenced by the lifestyle and the physical health and environment of the parent,” Dr. Bole said. “So how could these drugs potentially affect those epigenetic changes that then potentially are passed on to the offspring? We don’t know that.” 

An ideal source for that data would be a cohort registry of people who are taking the medication and then cause a pregnancy. “They have a registry for pregnant women,” Dr. Machineni said, “but we need something similar for men.”

Dr. Sadeghi-Nejad said that he and his coauthors are working on developing a registry for men who take GLP-1 RAs that would enable long-term tracking of multiple andrologic outcomes, including fertility and sexual dysfunction. Such a registry could theoretically be useful in tracking pregnancy and offspring outcomes as well. 
 

Too Soon for Prescribing

Additional options for treating fertility in men with obesity would be welcome. Current treatments include the selective estrogen receptor modulator (SERM) clomiphene citrate and the aromatase inhibitor anastrozole. But these have their drawbacks, Dr. Sadeghi-Nejad pointed out; in the overweight population in particular, they “are not necessarily ideal,” he said.

“Although both are viable treatments for enhancing hormonal balance and semen parameters, clomiphene citrate has rare but documented side effects, including thromboembolism, gastrointestinal distress and occasional weight gain in men,” Dr. Sadeghi-Nejad and his colleagues wrote. “Furthermore, despite clomiphene citrate’s association with significant increases in sperm concentration, it is not universally effective, with a meta-analysis indicating a significant increase in sperm concentration in approximately 60% of men.” 

For men who have obesity and oligospermia but normal levels of testosterone and estradiol, “conventional pharmaceutical approaches like clomiphene may not be suitable,” the authors wrote. 

Still, GLP-1 RAs may have a role to play for this population. 

“I think it is within the wheelhouse of a reproductive urologist to consider those types of medications,” Dr. Lindsey said. For example, for a patient who has overweight or obesity, “does it make sense to think about doing clomiphene therapy, which we often do for someone who has low testosterone, in conjunction [with a GLP-1 agonist]? Maybe there’s a kind of an additive effect of having both on board.”

Dr. Ramasamy similarly noted that GLP-1 agonists cannot replace SERMs but may work “synergistically” with them.

“Despite the established popularity of GLP-1 receptor agonists, there may be some reluctance among urologists and fertility specialists to prescribe them, with some others advocating for their use to enhance semen parameters,” Dr. Ramasamy said. “However, robust scientific evidence is still lacking, necessitating caution and a wait for more substantial data.”

Even if GLP-1 RAs prove to have therapeutic benefit for fertility, considerations such as availability and cost may affect prescribing. 

“We do currently have safe and effective drugs that we use for male fertility, and those are generally nowhere near as expensive,” Dr. Bole said. “When we start talking about another drug that we can add, we have to think about the efficacy and the potential side effect but also, is this affordable for patients?” 

Eventually, once more evidence become available, all of the urologists who spoke with this news organization said that they expect discussion about the possible therapeutic utility of GLP-1 agonists to make its way into clinical guidelines.

“Obesity is such a huge impediment for fertility in the modern environment,” Dr. Machineni said. “We will have to clarify the use of these agents, so I think this will be a part of the guidelines some point, but I think we need more information.”

The research was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the American Cancer Society. The review authors and other quoted physicians reported no disclosures. Dr. Machineni has consulted for Novo Nordisk and Lilly and has conducted clinical trials with semaglutide and tirzepatide for those companies. 
 

A version of this article appeared on Medscape.com.

The explosion of interest in glucagon-like peptide 1 receptor agonists (GLP-1 RAs), such as semaglutide and tirzepatide, has raised questions about what therapeutic effects this class of medication might have beyond their current indications for type 2 diabetes and obesity. 

Recent clinical trials have recently identified benefits from GLP-1 agents for the heart, liver, and kidneys, but the current evidence base is murkier regarding how the drugs may affect male fertility. 

Experts say the connection between GLP-1 RAs and improved male fertility makes sense biologically. For starters, overweight and obesity are strongly associated with male infertility in several overlapping ways. Obesity can disrupt hormones linked to fertility, increase the risk for defective sperm, adversely affect semen quality, and even make sexual intercourse more difficult due to obesity’s link to erectile dysfunction. As a result, GLP-1 RAs should at least in theory boost male fertility in men who take the drugs to lose weight. 

But animal studies and a handful of small trials and observational data point to the potential for GLP-1 RAs to improve male fertility in other ways.

A recent narrative review on GLP-1 RAs and male reproductive health, published in the journal Medicina in December 2023, surveyed the potential of the drugs for male infertility and offered reason for optimism. 

Hossein Sadeghi-Nejad, MD, director of urology at NYU Langone Health, New York, and a coauthor of the article, said that one reason he and his colleagues conducted their analysis was the known association between weight loss and an increase in testosterone.

“Most of the animal studies that are out there show that this class of drugs does affect testosterone levels,” Dr. Sadeghi-Nejad said; they wanted to better understand what other evidence showed about GLP-1 agonists and other fertility factors. 
 

Link Between Obesity and Fertility

The recent paper first reviews the well-established link between obesity and poorer fertility outcomes. 

“Certainly, obesity poses a significant societal problem with substantial impacts on both overall health and economic aspects,” senior author Ranjith Ramasamy, MD, associate professor of urology and director of the reproductive urology Fellowship program at the University of Miami’s Miller School of Medicine, told this news organization. “The escalating global obesity rates raise concerns, especially in the field of male infertility, where excessive body fat induces intrinsic hormonal changes leading to alterations, eventually, in semen parameters.”

The authors noted that obesity has been linked in the research to worse assisted reproductive technology (ART) outcomes and to subfecundity, taking more than 12 months to achieve pregnancy. They also referenced a systematic review that found men with obesity were more likely to have lower sperm counts and less viable sperm.

“From our standpoint, I think the key point was to raise awareness about the fact that obesity, because of the aromatization of testosterone to estradiol [from excess adipose tissue], will affect the hormonal axis and the availability of testosterone and, therefore, indirectly affects spermatogenesis,” Dr. Sadeghi-Nejad said. 

Obesity is also linked to lower levels of inhibin B, which stimulates testosterone secretion in Sertoli cells, which, when combined with the proinflammatory state of obesity, “results in a less favorable environment for sperm production,” he said. Finally, the link between obesity and poorer sexual function further inhibits fertility potential, he added. 

Until recently, the primary treatments for obesity in men experiencing fertility problems have been lifestyle modifications or surgical interventions. But the recent approval of GLP-1 RA drugs for obesity present an additional option depending on how these drugs affect other fertility parameters. 
 

Direct or Indirect Effects?

Most of the available evidence on GLP-RAs and sperm parameters comes from preclinical research. One of the few clinical trials, published last year in the Journal of Clinical Medicine, investigated the effects of liraglutide in men with metabolic hypogonadism, a body mass index between (BMI) 30 and 40, and severe erectile dysfunction. 

Among the 110 men enrolled in the study, only the 35 participants who said that they were not seeking fatherhood received liraglutide. After 4 months of treatment, these men had significantly improved semen concentration, motility, and morphology than did those wanting to conceive who received conventional fertility treatment. Erectile dysfunction was also more improved in the liraglutide group, according to the researchers. 

Though this study demonstrated the potential for liraglutide to treat metabolic hypogonadism, the men in that group also had greater weight loss and BMI reduction than the other participants. The review cited several other studies — albeit small ones — in which weight loss was associated with improvements in sperm parameters, including one randomized controlled trial in which one group lost weight with liraglutide and the other with lifestyle modifications; both groups showed increases in the concentration and number of sperm. 

One of the key questions requiring further research, then, is whether GLP-1 agents have direct effects on male fertility independent of a reduction in obesity. The randomized controlled trials comparing liraglutide and lifestyle modifications failed to find additional effects on semen in the men taking liraglutide; however, the study had only 56 participants, and results from liraglutide cannot be generalized to potential effects of semaglutide or tirzepatide, Dr. Sadeghi-Nejad said.

“Determining the relative contributions of weight loss versus direct drug actions on fertility outcomes remains challenging without robust data,” Dr. Ramasamy said. “While acknowledged that diet and physical activity positively impact fertility, confirming the synergistic role of GLP-1 receptor agonists requires evidence from well-designed randomized clinical trials.” 

Rodent studies suggest that GLP-1 RAs may independently affect testicular function because GLP-1 receptors exist in Sertoli and Leydig cells of the testes. In one study, for example, obese mice who received the GLP-1 agonist exenatide for 8 weeks had “improved sperm motility, DNA integrity, and decreased expression of pro-inflammatory cytokines,” the authors of the review reported. But the precise mechanisms aren’t well understood. 

“We know that there are GLP-1 receptors in the reproductive tract, but the extent of the downstream effect of stimulating those receptors, I don’t think we know well,” said John P. Lindsey II, MD, MEng, assistant professor of urology at University of California San Francisco Health. 

Other hormonal effects of GLP-1 agonists, such as stimulating insulin production and better regulating blood glucose levels, are better understood, said Raevti Bole, MD, a urologist at Cleveland Clinic, in Ohio, but still other effects of the drugs may not yet be identified.

“I think the really big unknown is whether these types of drugs have effects that are not hormonal on male fertility and what those effects are, and how those affect sperm,” Dr. Bole said. “For example, we know that these drugs slow gastric emptying. Is it possible that slow gastric emptying affects some of the nutrients that you absorb, and that could affect fertility?” Similarly, she said, it’s not clear whether GLP-1 agonists would have any effects on the thyroid that could then affect fertility. 
 

Effects on Offspring

Another open question about GLP-1 RAs and male fertility is their potential effects on the offspring, said Sriram Machineni, MBBS, associate professor of endocrinology at the Albert Einstein College of Medicine in New York City. The clinical trials involving the drugs for treating type 2 diabetes and obesity required both men and women to use contraception. If sperm contributing to a pregnancy are exposed to a GLP-1 agent, “we don’t know what the consequences could be,” Dr. Machineni said. “Just increasing the fertility of the man is not enough. We need to make sure it’s safe long-term for the fetus.”

Dr. Bole also pointed out the need for understanding potential effects in the fetus.

“We know that there are epigenetic changes that can happen to sperm that are influenced by the lifestyle and the physical health and environment of the parent,” Dr. Bole said. “So how could these drugs potentially affect those epigenetic changes that then potentially are passed on to the offspring? We don’t know that.” 

An ideal source for that data would be a cohort registry of people who are taking the medication and then cause a pregnancy. “They have a registry for pregnant women,” Dr. Machineni said, “but we need something similar for men.”

Dr. Sadeghi-Nejad said that he and his coauthors are working on developing a registry for men who take GLP-1 RAs that would enable long-term tracking of multiple andrologic outcomes, including fertility and sexual dysfunction. Such a registry could theoretically be useful in tracking pregnancy and offspring outcomes as well. 
 

Too Soon for Prescribing

Additional options for treating fertility in men with obesity would be welcome. Current treatments include the selective estrogen receptor modulator (SERM) clomiphene citrate and the aromatase inhibitor anastrozole. But these have their drawbacks, Dr. Sadeghi-Nejad pointed out; in the overweight population in particular, they “are not necessarily ideal,” he said.

“Although both are viable treatments for enhancing hormonal balance and semen parameters, clomiphene citrate has rare but documented side effects, including thromboembolism, gastrointestinal distress and occasional weight gain in men,” Dr. Sadeghi-Nejad and his colleagues wrote. “Furthermore, despite clomiphene citrate’s association with significant increases in sperm concentration, it is not universally effective, with a meta-analysis indicating a significant increase in sperm concentration in approximately 60% of men.” 

For men who have obesity and oligospermia but normal levels of testosterone and estradiol, “conventional pharmaceutical approaches like clomiphene may not be suitable,” the authors wrote. 

Still, GLP-1 RAs may have a role to play for this population. 

“I think it is within the wheelhouse of a reproductive urologist to consider those types of medications,” Dr. Lindsey said. For example, for a patient who has overweight or obesity, “does it make sense to think about doing clomiphene therapy, which we often do for someone who has low testosterone, in conjunction [with a GLP-1 agonist]? Maybe there’s a kind of an additive effect of having both on board.”

Dr. Ramasamy similarly noted that GLP-1 agonists cannot replace SERMs but may work “synergistically” with them.

“Despite the established popularity of GLP-1 receptor agonists, there may be some reluctance among urologists and fertility specialists to prescribe them, with some others advocating for their use to enhance semen parameters,” Dr. Ramasamy said. “However, robust scientific evidence is still lacking, necessitating caution and a wait for more substantial data.”

Even if GLP-1 RAs prove to have therapeutic benefit for fertility, considerations such as availability and cost may affect prescribing. 

“We do currently have safe and effective drugs that we use for male fertility, and those are generally nowhere near as expensive,” Dr. Bole said. “When we start talking about another drug that we can add, we have to think about the efficacy and the potential side effect but also, is this affordable for patients?” 

Eventually, once more evidence become available, all of the urologists who spoke with this news organization said that they expect discussion about the possible therapeutic utility of GLP-1 agonists to make its way into clinical guidelines.

“Obesity is such a huge impediment for fertility in the modern environment,” Dr. Machineni said. “We will have to clarify the use of these agents, so I think this will be a part of the guidelines some point, but I think we need more information.”

The research was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the American Cancer Society. The review authors and other quoted physicians reported no disclosures. Dr. Machineni has consulted for Novo Nordisk and Lilly and has conducted clinical trials with semaglutide and tirzepatide for those companies. 
 

A version of this article appeared on Medscape.com.

The explosion of interest in glucagon-like peptide 1 receptor agonists (GLP-1 RAs), such as semaglutide and tirzepatide, has raised questions about what therapeutic effects this class of medication might have beyond their current indications for type 2 diabetes and obesity. 

Recent clinical trials have recently identified benefits from GLP-1 agents for the heart, liver, and kidneys, but the current evidence base is murkier regarding how the drugs may affect male fertility. 

Experts say the connection between GLP-1 RAs and improved male fertility makes sense biologically. For starters, overweight and obesity are strongly associated with male infertility in several overlapping ways. Obesity can disrupt hormones linked to fertility, increase the risk for defective sperm, adversely affect semen quality, and even make sexual intercourse more difficult due to obesity’s link to erectile dysfunction. As a result, GLP-1 RAs should at least in theory boost male fertility in men who take the drugs to lose weight. 

But animal studies and a handful of small trials and observational data point to the potential for GLP-1 RAs to improve male fertility in other ways.

A recent narrative review on GLP-1 RAs and male reproductive health, published in the journal Medicina in December 2023, surveyed the potential of the drugs for male infertility and offered reason for optimism. 

Hossein Sadeghi-Nejad, MD, director of urology at NYU Langone Health, New York, and a coauthor of the article, said that one reason he and his colleagues conducted their analysis was the known association between weight loss and an increase in testosterone.

“Most of the animal studies that are out there show that this class of drugs does affect testosterone levels,” Dr. Sadeghi-Nejad said; they wanted to better understand what other evidence showed about GLP-1 agonists and other fertility factors. 
 

Link Between Obesity and Fertility

The recent paper first reviews the well-established link between obesity and poorer fertility outcomes. 

“Certainly, obesity poses a significant societal problem with substantial impacts on both overall health and economic aspects,” senior author Ranjith Ramasamy, MD, associate professor of urology and director of the reproductive urology Fellowship program at the University of Miami’s Miller School of Medicine, told this news organization. “The escalating global obesity rates raise concerns, especially in the field of male infertility, where excessive body fat induces intrinsic hormonal changes leading to alterations, eventually, in semen parameters.”

The authors noted that obesity has been linked in the research to worse assisted reproductive technology (ART) outcomes and to subfecundity, taking more than 12 months to achieve pregnancy. They also referenced a systematic review that found men with obesity were more likely to have lower sperm counts and less viable sperm.

“From our standpoint, I think the key point was to raise awareness about the fact that obesity, because of the aromatization of testosterone to estradiol [from excess adipose tissue], will affect the hormonal axis and the availability of testosterone and, therefore, indirectly affects spermatogenesis,” Dr. Sadeghi-Nejad said. 

Obesity is also linked to lower levels of inhibin B, which stimulates testosterone secretion in Sertoli cells, which, when combined with the proinflammatory state of obesity, “results in a less favorable environment for sperm production,” he said. Finally, the link between obesity and poorer sexual function further inhibits fertility potential, he added. 

Until recently, the primary treatments for obesity in men experiencing fertility problems have been lifestyle modifications or surgical interventions. But the recent approval of GLP-1 RA drugs for obesity present an additional option depending on how these drugs affect other fertility parameters. 
 

Direct or Indirect Effects?

Most of the available evidence on GLP-RAs and sperm parameters comes from preclinical research. One of the few clinical trials, published last year in the Journal of Clinical Medicine, investigated the effects of liraglutide in men with metabolic hypogonadism, a body mass index between (BMI) 30 and 40, and severe erectile dysfunction. 

Among the 110 men enrolled in the study, only the 35 participants who said that they were not seeking fatherhood received liraglutide. After 4 months of treatment, these men had significantly improved semen concentration, motility, and morphology than did those wanting to conceive who received conventional fertility treatment. Erectile dysfunction was also more improved in the liraglutide group, according to the researchers. 

Though this study demonstrated the potential for liraglutide to treat metabolic hypogonadism, the men in that group also had greater weight loss and BMI reduction than the other participants. The review cited several other studies — albeit small ones — in which weight loss was associated with improvements in sperm parameters, including one randomized controlled trial in which one group lost weight with liraglutide and the other with lifestyle modifications; both groups showed increases in the concentration and number of sperm. 

One of the key questions requiring further research, then, is whether GLP-1 agents have direct effects on male fertility independent of a reduction in obesity. The randomized controlled trials comparing liraglutide and lifestyle modifications failed to find additional effects on semen in the men taking liraglutide; however, the study had only 56 participants, and results from liraglutide cannot be generalized to potential effects of semaglutide or tirzepatide, Dr. Sadeghi-Nejad said.

“Determining the relative contributions of weight loss versus direct drug actions on fertility outcomes remains challenging without robust data,” Dr. Ramasamy said. “While acknowledged that diet and physical activity positively impact fertility, confirming the synergistic role of GLP-1 receptor agonists requires evidence from well-designed randomized clinical trials.” 

Rodent studies suggest that GLP-1 RAs may independently affect testicular function because GLP-1 receptors exist in Sertoli and Leydig cells of the testes. In one study, for example, obese mice who received the GLP-1 agonist exenatide for 8 weeks had “improved sperm motility, DNA integrity, and decreased expression of pro-inflammatory cytokines,” the authors of the review reported. But the precise mechanisms aren’t well understood. 

“We know that there are GLP-1 receptors in the reproductive tract, but the extent of the downstream effect of stimulating those receptors, I don’t think we know well,” said John P. Lindsey II, MD, MEng, assistant professor of urology at University of California San Francisco Health. 

Other hormonal effects of GLP-1 agonists, such as stimulating insulin production and better regulating blood glucose levels, are better understood, said Raevti Bole, MD, a urologist at Cleveland Clinic, in Ohio, but still other effects of the drugs may not yet be identified.

“I think the really big unknown is whether these types of drugs have effects that are not hormonal on male fertility and what those effects are, and how those affect sperm,” Dr. Bole said. “For example, we know that these drugs slow gastric emptying. Is it possible that slow gastric emptying affects some of the nutrients that you absorb, and that could affect fertility?” Similarly, she said, it’s not clear whether GLP-1 agonists would have any effects on the thyroid that could then affect fertility. 
 

Effects on Offspring

Another open question about GLP-1 RAs and male fertility is their potential effects on the offspring, said Sriram Machineni, MBBS, associate professor of endocrinology at the Albert Einstein College of Medicine in New York City. The clinical trials involving the drugs for treating type 2 diabetes and obesity required both men and women to use contraception. If sperm contributing to a pregnancy are exposed to a GLP-1 agent, “we don’t know what the consequences could be,” Dr. Machineni said. “Just increasing the fertility of the man is not enough. We need to make sure it’s safe long-term for the fetus.”

Dr. Bole also pointed out the need for understanding potential effects in the fetus.

“We know that there are epigenetic changes that can happen to sperm that are influenced by the lifestyle and the physical health and environment of the parent,” Dr. Bole said. “So how could these drugs potentially affect those epigenetic changes that then potentially are passed on to the offspring? We don’t know that.” 

An ideal source for that data would be a cohort registry of people who are taking the medication and then cause a pregnancy. “They have a registry for pregnant women,” Dr. Machineni said, “but we need something similar for men.”

Dr. Sadeghi-Nejad said that he and his coauthors are working on developing a registry for men who take GLP-1 RAs that would enable long-term tracking of multiple andrologic outcomes, including fertility and sexual dysfunction. Such a registry could theoretically be useful in tracking pregnancy and offspring outcomes as well. 
 

Too Soon for Prescribing

Additional options for treating fertility in men with obesity would be welcome. Current treatments include the selective estrogen receptor modulator (SERM) clomiphene citrate and the aromatase inhibitor anastrozole. But these have their drawbacks, Dr. Sadeghi-Nejad pointed out; in the overweight population in particular, they “are not necessarily ideal,” he said.

“Although both are viable treatments for enhancing hormonal balance and semen parameters, clomiphene citrate has rare but documented side effects, including thromboembolism, gastrointestinal distress and occasional weight gain in men,” Dr. Sadeghi-Nejad and his colleagues wrote. “Furthermore, despite clomiphene citrate’s association with significant increases in sperm concentration, it is not universally effective, with a meta-analysis indicating a significant increase in sperm concentration in approximately 60% of men.” 

For men who have obesity and oligospermia but normal levels of testosterone and estradiol, “conventional pharmaceutical approaches like clomiphene may not be suitable,” the authors wrote. 

Still, GLP-1 RAs may have a role to play for this population. 

“I think it is within the wheelhouse of a reproductive urologist to consider those types of medications,” Dr. Lindsey said. For example, for a patient who has overweight or obesity, “does it make sense to think about doing clomiphene therapy, which we often do for someone who has low testosterone, in conjunction [with a GLP-1 agonist]? Maybe there’s a kind of an additive effect of having both on board.”

Dr. Ramasamy similarly noted that GLP-1 agonists cannot replace SERMs but may work “synergistically” with them.

“Despite the established popularity of GLP-1 receptor agonists, there may be some reluctance among urologists and fertility specialists to prescribe them, with some others advocating for their use to enhance semen parameters,” Dr. Ramasamy said. “However, robust scientific evidence is still lacking, necessitating caution and a wait for more substantial data.”

Even if GLP-1 RAs prove to have therapeutic benefit for fertility, considerations such as availability and cost may affect prescribing. 

“We do currently have safe and effective drugs that we use for male fertility, and those are generally nowhere near as expensive,” Dr. Bole said. “When we start talking about another drug that we can add, we have to think about the efficacy and the potential side effect but also, is this affordable for patients?” 

Eventually, once more evidence become available, all of the urologists who spoke with this news organization said that they expect discussion about the possible therapeutic utility of GLP-1 agonists to make its way into clinical guidelines.

“Obesity is such a huge impediment for fertility in the modern environment,” Dr. Machineni said. “We will have to clarify the use of these agents, so I think this will be a part of the guidelines some point, but I think we need more information.”

The research was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the American Cancer Society. The review authors and other quoted physicians reported no disclosures. Dr. Machineni has consulted for Novo Nordisk and Lilly and has conducted clinical trials with semaglutide and tirzepatide for those companies. 
 

A version of this article appeared on Medscape.com.

Injectable weight loss drugs like Wegovy, Saxenda, and Zepbound have been getting all the glory lately, but they’re not for everyone. If the inconvenience or cost of weight-loss drugs isn’t for you, another approach may be boosting your gut microbiome.

So how does one do that, and how does it work?

“There are a lot of different factors naturally in weight gain and weight loss, so the gut microbiome is certainly not the only thing,” said Chris Damman, MD, a gastroenterologist at the University of Washington. He studies how food and the microbiome affect your health. “With that caveat, it probably is playing an important role.”
 

Trillions of Microbes

The idea that your gut is home to an enormous range of tiny organisms — microbes — has existed for more than 100 years, but only in the 21st century have scientists had the ability to delve into specifics. 

We now know you want a robust assortment of microbes in your gut, especially in the lower gut, your colon. They feast on fiber from the food you eat and turn it into substances your body needs. Those substances send signals all over your body.

If you don’t have enough microbes or have too many of the wrong kinds, it influences those signals, which can lead to health problems. Over the last 20 years, research has linked problems in the gut microbiome to a wide variety of conditions, including inflammatory bowel disease, autoimmune diseases like rheumatoid arthritis, metabolic ones like diabetes, and cardiovascular disease, asthma, and even autism.

Thanks to these efforts, we know a lot about the interactions between your gut and the rest of your body, but we don’t know exactly how many things happen — whether some teeny critters within your microbiome cause the issues or vice versa.

“That’s the problem with so much of the microbiome stuff,” said Elizabeth Hohmann, MD, a physician investigator at the Massachusetts General Research Institute. “Olympic athletes have a better gut microbiome than most people. Well, sure they do — because they’re paying attention to their diet, they’re getting enough rest. Correlation does not causation make.”
 

The American Diet Messes With Your Gut

If you’re a typical American, you eat a lot of ultra-processed foods — manufactured with a long ingredients list that includes additives or preservatives. According to one study, those foods make up 73% of our food supply. That can have a serious impact on gut health.

“When you process a food and mill it, it turns a whole food into tiny particles,” Dr. Damman said. “That makes the food highly digestible. But if you eat a stalk of broccoli, a large amount of that broccoli in the form of fiber and other things will make its way to your lower gut, where it will feed microbes.”

With heavily processed foods, on the other hand, most of it gets digested before it can reach your lower gut, which leaves your microbes without the energy they need to survive.

Rosa Krajmalnik-Brown, PhD, is director of the Biodesign Center for Health Through Microbiomes at Arizona State University. Her lab has done research into how microbes use the undigested food that reaches your gut. She describes the problem with processed foods this way:

“Think about a Coke. When you drink it, all the sugar goes to your bloodstream, and the microbes in your gut don’t even know you’ve had it. Instead of drinking a Coke, if you eat an apple or something with fiber, some will go to you and some to the microbes. You’re feeding them, giving them energy.”
 

Weight and Your Gut Microbiome

The link between gut health and body weight has received a lot of attention. Research has shown, for example, that people with obesity have less diversity in their gut microbiome, and certain specific bacteria have been linked to obesity. In animal studies, transplanting gut microbes from obese mice to “germ-free” mice led those GF mice to gain weight. This suggests excess weight is, in fact, caused by certain microbes, but to date there’s scant evidence that the same is true with humans.

Dr. Krajmalnik-Brown’s group did an experiment in which they had people follow two different diets for 23 days each, with a break in between. Both provided similar amounts of calories and macronutrients each day but via different foods. The study’s typical Western menu featured processed foods — think grape juice, sandwiches made with deli turkey and white bread, and spaghetti with jarred sauce and ground beef. The other menu, what researchers called a “microbiome enhancer diet,” included foods like whole fruit, veggie sandwiches on multigrain buns, and steak with a side of whole wheat spaghetti.

While the study wasn’t designed for weight loss, an interesting thing happened when researchers analyzed participants’ bowel movements.

“We found that when you feed subjects a diet designed to provide more energy to the microbes and not to the [body], our subjects lost a little weight,” Dr. Krajmalnik-Brown said. “It looks like by feeding your microbes, it seems to make people healthier and potentially even lose a little.”

Another possible mechanism involves the same hormone that powers those injectable weight loss drugs. The lower part of your gut makes hormones that tell the entire gut to slow down and also help orchestrate metabolism and appetite. Among them is GLP-1. The drugs use a synthetic version, semaglutide or tirzepatide, to trigger the same effect.

According to Dr. Damman, you can stimulate your gut to make those helpful hormones with the food you eat — by giving your microbes the right fuel.
 

Eat to Feed Your Microbes

The foods you eat can affect your gut microbiome and so your weight. But don’t go looking for that one perfect ingredient, experts warn.

“Oftentimes we get this micro-focus, is this a good food or a bad food?” warned Katie Chapmon, a registered dietitian whose practice focuses on gut health. “You just want to make sure your microbiome is robust and healthy, so it communicates that your body is running, you’ve got it.”

Instead, try to give your body more of the kinds of food research has shown can feed your microbiome, many of which are plant-based. “Those are the things that are largely taken out during processing,” Dr. Damman said. He calls them the “Four Fs”:

Fiber: When you eat fiber-rich foods like fruits, vegetables, whole grains, nuts, and beans, your body can’t digest the fiber while it’s in the upper parts of your GI tract. It passes through to your lower gut, where healthy bacteria ferment it. That produces short-chain fatty acids, which send signals throughout your body, including ones related to appetite and feeling full.

Phenols: Phenolic compounds are antioxidants that give plant-based foods their color — when you talk about eating the rainbow, you’re talking about phenols. The microbes in your gut feed on them, too. “My goal for a meal is five distinct colors on the plate,” Ms. Chapmon said. “That rounds out the bases for the different polyphenols.”

Fermented foods: You can get a different kind of health benefit by eating food that’s already fermented — like sauerkraut, kimchi, kefir, yogurt, miso, tempeh, and kombucha. Fermentation can make the phenols in foods more accessible to your body. Plus, each mouthful introduces good bacteria into your body, some of which make it down to your gut. The bacteria that are already there feed on these new strains, which helps to increase the diversity of your microbiome.

Healthy fats: Here, it’s not so much about feeding the good bacteria in your microbiome. Dr. Damman says that omega-3 fatty acids, found in fatty fish, canola oil, some nuts, and other foods, decrease inflammation in the lining of your gut. Plus, healthy fat sources like extra-virgin olive oil and avocados are full of phenols.

Eating for gut health isn’t a magic bullet in terms of weight loss. But the benefits of a healthy gut go far beyond shedding a few pounds.

“I think we need to strive for health, not weight loss.” Dr. Krajmalnik-Brown said. “Keep your gut healthy and your microbes healthy, and that should eventually lead to a healthy weight. You’ll make your microbes happy, and your microbes do a lot for your health.”

A version of this article appeared on WebMD.com.

Injectable weight loss drugs like Wegovy, Saxenda, and Zepbound have been getting all the glory lately, but they’re not for everyone. If the inconvenience or cost of weight-loss drugs isn’t for you, another approach may be boosting your gut microbiome.

So how does one do that, and how does it work?

“There are a lot of different factors naturally in weight gain and weight loss, so the gut microbiome is certainly not the only thing,” said Chris Damman, MD, a gastroenterologist at the University of Washington. He studies how food and the microbiome affect your health. “With that caveat, it probably is playing an important role.”
 

Trillions of Microbes

The idea that your gut is home to an enormous range of tiny organisms — microbes — has existed for more than 100 years, but only in the 21st century have scientists had the ability to delve into specifics. 

We now know you want a robust assortment of microbes in your gut, especially in the lower gut, your colon. They feast on fiber from the food you eat and turn it into substances your body needs. Those substances send signals all over your body.

If you don’t have enough microbes or have too many of the wrong kinds, it influences those signals, which can lead to health problems. Over the last 20 years, research has linked problems in the gut microbiome to a wide variety of conditions, including inflammatory bowel disease, autoimmune diseases like rheumatoid arthritis, metabolic ones like diabetes, and cardiovascular disease, asthma, and even autism.

Thanks to these efforts, we know a lot about the interactions between your gut and the rest of your body, but we don’t know exactly how many things happen — whether some teeny critters within your microbiome cause the issues or vice versa.

“That’s the problem with so much of the microbiome stuff,” said Elizabeth Hohmann, MD, a physician investigator at the Massachusetts General Research Institute. “Olympic athletes have a better gut microbiome than most people. Well, sure they do — because they’re paying attention to their diet, they’re getting enough rest. Correlation does not causation make.”
 

The American Diet Messes With Your Gut

If you’re a typical American, you eat a lot of ultra-processed foods — manufactured with a long ingredients list that includes additives or preservatives. According to one study, those foods make up 73% of our food supply. That can have a serious impact on gut health.

“When you process a food and mill it, it turns a whole food into tiny particles,” Dr. Damman said. “That makes the food highly digestible. But if you eat a stalk of broccoli, a large amount of that broccoli in the form of fiber and other things will make its way to your lower gut, where it will feed microbes.”

With heavily processed foods, on the other hand, most of it gets digested before it can reach your lower gut, which leaves your microbes without the energy they need to survive.

Rosa Krajmalnik-Brown, PhD, is director of the Biodesign Center for Health Through Microbiomes at Arizona State University. Her lab has done research into how microbes use the undigested food that reaches your gut. She describes the problem with processed foods this way:

“Think about a Coke. When you drink it, all the sugar goes to your bloodstream, and the microbes in your gut don’t even know you’ve had it. Instead of drinking a Coke, if you eat an apple or something with fiber, some will go to you and some to the microbes. You’re feeding them, giving them energy.”
 

Weight and Your Gut Microbiome

The link between gut health and body weight has received a lot of attention. Research has shown, for example, that people with obesity have less diversity in their gut microbiome, and certain specific bacteria have been linked to obesity. In animal studies, transplanting gut microbes from obese mice to “germ-free” mice led those GF mice to gain weight. This suggests excess weight is, in fact, caused by certain microbes, but to date there’s scant evidence that the same is true with humans.

Dr. Krajmalnik-Brown’s group did an experiment in which they had people follow two different diets for 23 days each, with a break in between. Both provided similar amounts of calories and macronutrients each day but via different foods. The study’s typical Western menu featured processed foods — think grape juice, sandwiches made with deli turkey and white bread, and spaghetti with jarred sauce and ground beef. The other menu, what researchers called a “microbiome enhancer diet,” included foods like whole fruit, veggie sandwiches on multigrain buns, and steak with a side of whole wheat spaghetti.

While the study wasn’t designed for weight loss, an interesting thing happened when researchers analyzed participants’ bowel movements.

“We found that when you feed subjects a diet designed to provide more energy to the microbes and not to the [body], our subjects lost a little weight,” Dr. Krajmalnik-Brown said. “It looks like by feeding your microbes, it seems to make people healthier and potentially even lose a little.”

Another possible mechanism involves the same hormone that powers those injectable weight loss drugs. The lower part of your gut makes hormones that tell the entire gut to slow down and also help orchestrate metabolism and appetite. Among them is GLP-1. The drugs use a synthetic version, semaglutide or tirzepatide, to trigger the same effect.

According to Dr. Damman, you can stimulate your gut to make those helpful hormones with the food you eat — by giving your microbes the right fuel.
 

Eat to Feed Your Microbes

The foods you eat can affect your gut microbiome and so your weight. But don’t go looking for that one perfect ingredient, experts warn.

“Oftentimes we get this micro-focus, is this a good food or a bad food?” warned Katie Chapmon, a registered dietitian whose practice focuses on gut health. “You just want to make sure your microbiome is robust and healthy, so it communicates that your body is running, you’ve got it.”

Instead, try to give your body more of the kinds of food research has shown can feed your microbiome, many of which are plant-based. “Those are the things that are largely taken out during processing,” Dr. Damman said. He calls them the “Four Fs”:

Fiber: When you eat fiber-rich foods like fruits, vegetables, whole grains, nuts, and beans, your body can’t digest the fiber while it’s in the upper parts of your GI tract. It passes through to your lower gut, where healthy bacteria ferment it. That produces short-chain fatty acids, which send signals throughout your body, including ones related to appetite and feeling full.

Phenols: Phenolic compounds are antioxidants that give plant-based foods their color — when you talk about eating the rainbow, you’re talking about phenols. The microbes in your gut feed on them, too. “My goal for a meal is five distinct colors on the plate,” Ms. Chapmon said. “That rounds out the bases for the different polyphenols.”

Fermented foods: You can get a different kind of health benefit by eating food that’s already fermented — like sauerkraut, kimchi, kefir, yogurt, miso, tempeh, and kombucha. Fermentation can make the phenols in foods more accessible to your body. Plus, each mouthful introduces good bacteria into your body, some of which make it down to your gut. The bacteria that are already there feed on these new strains, which helps to increase the diversity of your microbiome.

Healthy fats: Here, it’s not so much about feeding the good bacteria in your microbiome. Dr. Damman says that omega-3 fatty acids, found in fatty fish, canola oil, some nuts, and other foods, decrease inflammation in the lining of your gut. Plus, healthy fat sources like extra-virgin olive oil and avocados are full of phenols.

Eating for gut health isn’t a magic bullet in terms of weight loss. But the benefits of a healthy gut go far beyond shedding a few pounds.

“I think we need to strive for health, not weight loss.” Dr. Krajmalnik-Brown said. “Keep your gut healthy and your microbes healthy, and that should eventually lead to a healthy weight. You’ll make your microbes happy, and your microbes do a lot for your health.”

A version of this article appeared on WebMD.com.

Injectable weight loss drugs like Wegovy, Saxenda, and Zepbound have been getting all the glory lately, but they’re not for everyone. If the inconvenience or cost of weight-loss drugs isn’t for you, another approach may be boosting your gut microbiome.

So how does one do that, and how does it work?

“There are a lot of different factors naturally in weight gain and weight loss, so the gut microbiome is certainly not the only thing,” said Chris Damman, MD, a gastroenterologist at the University of Washington. He studies how food and the microbiome affect your health. “With that caveat, it probably is playing an important role.”
 

Trillions of Microbes

The idea that your gut is home to an enormous range of tiny organisms — microbes — has existed for more than 100 years, but only in the 21st century have scientists had the ability to delve into specifics. 

We now know you want a robust assortment of microbes in your gut, especially in the lower gut, your colon. They feast on fiber from the food you eat and turn it into substances your body needs. Those substances send signals all over your body.

If you don’t have enough microbes or have too many of the wrong kinds, it influences those signals, which can lead to health problems. Over the last 20 years, research has linked problems in the gut microbiome to a wide variety of conditions, including inflammatory bowel disease, autoimmune diseases like rheumatoid arthritis, metabolic ones like diabetes, and cardiovascular disease, asthma, and even autism.

Thanks to these efforts, we know a lot about the interactions between your gut and the rest of your body, but we don’t know exactly how many things happen — whether some teeny critters within your microbiome cause the issues or vice versa.

“That’s the problem with so much of the microbiome stuff,” said Elizabeth Hohmann, MD, a physician investigator at the Massachusetts General Research Institute. “Olympic athletes have a better gut microbiome than most people. Well, sure they do — because they’re paying attention to their diet, they’re getting enough rest. Correlation does not causation make.”
 

The American Diet Messes With Your Gut

If you’re a typical American, you eat a lot of ultra-processed foods — manufactured with a long ingredients list that includes additives or preservatives. According to one study, those foods make up 73% of our food supply. That can have a serious impact on gut health.

“When you process a food and mill it, it turns a whole food into tiny particles,” Dr. Damman said. “That makes the food highly digestible. But if you eat a stalk of broccoli, a large amount of that broccoli in the form of fiber and other things will make its way to your lower gut, where it will feed microbes.”

With heavily processed foods, on the other hand, most of it gets digested before it can reach your lower gut, which leaves your microbes without the energy they need to survive.

Rosa Krajmalnik-Brown, PhD, is director of the Biodesign Center for Health Through Microbiomes at Arizona State University. Her lab has done research into how microbes use the undigested food that reaches your gut. She describes the problem with processed foods this way:

“Think about a Coke. When you drink it, all the sugar goes to your bloodstream, and the microbes in your gut don’t even know you’ve had it. Instead of drinking a Coke, if you eat an apple or something with fiber, some will go to you and some to the microbes. You’re feeding them, giving them energy.”
 

Weight and Your Gut Microbiome

The link between gut health and body weight has received a lot of attention. Research has shown, for example, that people with obesity have less diversity in their gut microbiome, and certain specific bacteria have been linked to obesity. In animal studies, transplanting gut microbes from obese mice to “germ-free” mice led those GF mice to gain weight. This suggests excess weight is, in fact, caused by certain microbes, but to date there’s scant evidence that the same is true with humans.

Dr. Krajmalnik-Brown’s group did an experiment in which they had people follow two different diets for 23 days each, with a break in between. Both provided similar amounts of calories and macronutrients each day but via different foods. The study’s typical Western menu featured processed foods — think grape juice, sandwiches made with deli turkey and white bread, and spaghetti with jarred sauce and ground beef. The other menu, what researchers called a “microbiome enhancer diet,” included foods like whole fruit, veggie sandwiches on multigrain buns, and steak with a side of whole wheat spaghetti.

While the study wasn’t designed for weight loss, an interesting thing happened when researchers analyzed participants’ bowel movements.

“We found that when you feed subjects a diet designed to provide more energy to the microbes and not to the [body], our subjects lost a little weight,” Dr. Krajmalnik-Brown said. “It looks like by feeding your microbes, it seems to make people healthier and potentially even lose a little.”

Another possible mechanism involves the same hormone that powers those injectable weight loss drugs. The lower part of your gut makes hormones that tell the entire gut to slow down and also help orchestrate metabolism and appetite. Among them is GLP-1. The drugs use a synthetic version, semaglutide or tirzepatide, to trigger the same effect.

According to Dr. Damman, you can stimulate your gut to make those helpful hormones with the food you eat — by giving your microbes the right fuel.
 

Eat to Feed Your Microbes

The foods you eat can affect your gut microbiome and so your weight. But don’t go looking for that one perfect ingredient, experts warn.

“Oftentimes we get this micro-focus, is this a good food or a bad food?” warned Katie Chapmon, a registered dietitian whose practice focuses on gut health. “You just want to make sure your microbiome is robust and healthy, so it communicates that your body is running, you’ve got it.”

Instead, try to give your body more of the kinds of food research has shown can feed your microbiome, many of which are plant-based. “Those are the things that are largely taken out during processing,” Dr. Damman said. He calls them the “Four Fs”:

Fiber: When you eat fiber-rich foods like fruits, vegetables, whole grains, nuts, and beans, your body can’t digest the fiber while it’s in the upper parts of your GI tract. It passes through to your lower gut, where healthy bacteria ferment it. That produces short-chain fatty acids, which send signals throughout your body, including ones related to appetite and feeling full.

Phenols: Phenolic compounds are antioxidants that give plant-based foods their color — when you talk about eating the rainbow, you’re talking about phenols. The microbes in your gut feed on them, too. “My goal for a meal is five distinct colors on the plate,” Ms. Chapmon said. “That rounds out the bases for the different polyphenols.”

Fermented foods: You can get a different kind of health benefit by eating food that’s already fermented — like sauerkraut, kimchi, kefir, yogurt, miso, tempeh, and kombucha. Fermentation can make the phenols in foods more accessible to your body. Plus, each mouthful introduces good bacteria into your body, some of which make it down to your gut. The bacteria that are already there feed on these new strains, which helps to increase the diversity of your microbiome.

Healthy fats: Here, it’s not so much about feeding the good bacteria in your microbiome. Dr. Damman says that omega-3 fatty acids, found in fatty fish, canola oil, some nuts, and other foods, decrease inflammation in the lining of your gut. Plus, healthy fat sources like extra-virgin olive oil and avocados are full of phenols.

Eating for gut health isn’t a magic bullet in terms of weight loss. But the benefits of a healthy gut go far beyond shedding a few pounds.

“I think we need to strive for health, not weight loss.” Dr. Krajmalnik-Brown said. “Keep your gut healthy and your microbes healthy, and that should eventually lead to a healthy weight. You’ll make your microbes happy, and your microbes do a lot for your health.”

A version of this article appeared on WebMD.com.

Many patients with obesity blame weight gain on their metabolism. The reality is that metabolism can be blamed for weight regain after people try to lose weight! As we age, our metabolism does slow down; sometimes we think it stops working.

Metabolism, or resting energy expenditure, is directly related to how much muscle mass we have. As we age, we lose muscle, which is called sarcopenia.

What happens to our metabolism when we try to lose weight? Let’s first discuss what metabolism is.
 

What Is Metabolism?

Metabolism refers to the chemical reactions in the body’s cells that convert food into energy for sustaining life, cellular processes, and as storage for a rainy day.

Total energy expenditure (TEE) is broken down into resting energy expenditure (REE), thermic effect of food (TEF), and nonresting expenditure (NREE) or physical activity, and is made up of: TEE = 60% REE + 10% TEF + 30% NREE.

An elegant study performed by Dr. Rudy Leibel explored the effects of weight loss or weight gain on metabolism in 23 lean and 18 patients with obesity who were placed in a metabolic chamber. Weight loss of 10% or 20% body weight led to a decrease in TEE roughly equal to about 300 kcal/d, and an increase in body weight of 10% caused an increase in TEE of about 500 kcal/d. These changes led to the patient reverting to the prior weight (before weight loss or gain). In other words, Dr. Leibel postulated a feedback mechanism for the effect of fat mass decrease or increase on energy metabolism. The feedback mechanism or signal from fat was subsequently found to be leptin.

In a later study, Dr. Leibel and colleagues investigated the effects of body fat mass change on TEE and found that a 10% reduction in weight caused a decrease of TEE by 21%, comprising a decrease in NREE of 37.5% and a decrease in REE of 11.6%.

Therefore, the biggest change in TEE comes from NREE or exercise energy expenditure. The 35% variance in NEE change was accounted for by a decrease in muscle work efficiency in generating 10 watts or low levels of work such as walking.

In other words, when persons with obesity or lean persons lose weight, the efficiency of muscle at low levels of work increases such that one burns less energy when walking than one normally would. This helps conserve energy and tends to cause the body to go back to the higher weight.
 

So, How Can One Change Metabolism?

Let’s say one did lose weight and wants to counteract this TEE loss and increased muscle efficiency at low levels of work.

To counteract this effect, one should increase muscle work beyond low level so that more energy is expended. Another way would be to increase muscle mass so that there is more muscle that can do work.

This is exactly how metabolism can be altered or increased. What can be changed most readily, and what we have the most power over in our bodies, is the NREE.

To do this, muscles need anabolic power — the power to heal and build muscle mass. Anabolic power comes from eating healthy protein sources such as lean chicken, fish, beef, and eggs as well as dry beans, tofu, and dairy products.. It seems that older adults (> 60 years) need more protein than younger adults to build muscle mass, due to the body’s natural aging process which leads to sarcopenia. How much more? Studies show between 1.2 and 1.5 g/kg of body weight per day, whereas younger persons need 0.80 g/kg.

Developing sarcopenia with age involves muscle losing the ability to use protein and amino acids to rebuild injured tissue.

Let’s put this in perspective for treating obesity.

Obesity is brought on by the body’s defense of a higher body weight by interaction with the environment of highly processed foods that work on the reward pathway, leading to weight gain and resistance to satiety. Weight loss via diet, exercise, and medications works, but this weight loss is also accompanied by a decrease in TEE.

Weight loss is primarily fat mass loss, but depending on the degree of protein intake and muscle resistance training, 20%-50% of the total weight loss is muscle mass loss. Therefore, higher-protein diets and resistance exercise can be useful in preserving muscle mass and counteracting the decrease in TEE, maintaining energy expenditure. In older patients, an additional factor is the muscle’s lack of ability to use protein as an anabolic agent to protect muscle mass and thus the need for higher protein loads to do this.

All in all, can doctors help patients boost their metabolism, especially as they lose weight and maintain that loss? Yes — through protein intake and resistance exercise training.

Here are some tips to help your patients get cardio and resistance exercise into their routine.

First find out whether your patient prefers a social exercise interaction or solo training. If social, then the gym or classes such as cycling or boot camps at those gyms may work for them, especially if they can go with a friend. If solo is better, than a gym in the home might work. Peloton bikes are expensive but the interaction is all on the website!

A personal trainer may help motivate the patient if they know someone is waiting for them.

Let’s hit the gym!

Another note: There are agents in the obesity treatment pipeline that purport to change body composition while helping patients lose weight. Some of these agents are myostatin antagonists and antibodies that inhibit the activity of myostatin to break down muscle. These agents have been found to build muscle mass, but whether the quality of the muscle mass leads to an increase in muscle strength or functionality remains controversial. The next frontier in obesity treatment will be about decreasing fat mass and increasing muscle mass while making sure that increased muscle mass leads to improved functionality.

In the meantime, aside from new agents on the horizon, the best and healthiest way to keep metabolism on the up and up is to eat healthy lean proteins and exercise. How much exercise? The recommendation is 30-60 minutes of moderate to vigorous physical activity at least 5 days per week; plus 20 minutes of resistance exercise training 2-3 days per week for upper- and lower-extremity and core strength.

Again, let’s hit the gym!
 

Dr. Apovian is in the department of medicine, and codirector, Center for Weight Management and Wellness, Section of Endocrinology, Diabetes, and Hypertension, at Brigham and Women’s Hospital, Harvard Medical School, Boston. She disclosed ties with Altimmune, Cowen and Company, Currax Pharmaceuticals, EPG Communication Holdings, Gelesis, Srl, L-Nutra, and NeuroBo Pharmaceuticals, and Novo Nordisk. She received research grant from the National Institutes of Health, Patient-Centered Outcomes Research Institute, and GI Dynamics.

A version of this article appeared on Medscape.com.

Many patients with obesity blame weight gain on their metabolism. The reality is that metabolism can be blamed for weight regain after people try to lose weight! As we age, our metabolism does slow down; sometimes we think it stops working.

Metabolism, or resting energy expenditure, is directly related to how much muscle mass we have. As we age, we lose muscle, which is called sarcopenia.

What happens to our metabolism when we try to lose weight? Let’s first discuss what metabolism is.
 

What Is Metabolism?

Metabolism refers to the chemical reactions in the body’s cells that convert food into energy for sustaining life, cellular processes, and as storage for a rainy day.

Total energy expenditure (TEE) is broken down into resting energy expenditure (REE), thermic effect of food (TEF), and nonresting expenditure (NREE) or physical activity, and is made up of: TEE = 60% REE + 10% TEF + 30% NREE.

An elegant study performed by Dr. Rudy Leibel explored the effects of weight loss or weight gain on metabolism in 23 lean and 18 patients with obesity who were placed in a metabolic chamber. Weight loss of 10% or 20% body weight led to a decrease in TEE roughly equal to about 300 kcal/d, and an increase in body weight of 10% caused an increase in TEE of about 500 kcal/d. These changes led to the patient reverting to the prior weight (before weight loss or gain). In other words, Dr. Leibel postulated a feedback mechanism for the effect of fat mass decrease or increase on energy metabolism. The feedback mechanism or signal from fat was subsequently found to be leptin.

In a later study, Dr. Leibel and colleagues investigated the effects of body fat mass change on TEE and found that a 10% reduction in weight caused a decrease of TEE by 21%, comprising a decrease in NREE of 37.5% and a decrease in REE of 11.6%.

Therefore, the biggest change in TEE comes from NREE or exercise energy expenditure. The 35% variance in NEE change was accounted for by a decrease in muscle work efficiency in generating 10 watts or low levels of work such as walking.

In other words, when persons with obesity or lean persons lose weight, the efficiency of muscle at low levels of work increases such that one burns less energy when walking than one normally would. This helps conserve energy and tends to cause the body to go back to the higher weight.
 

So, How Can One Change Metabolism?

Let’s say one did lose weight and wants to counteract this TEE loss and increased muscle efficiency at low levels of work.

To counteract this effect, one should increase muscle work beyond low level so that more energy is expended. Another way would be to increase muscle mass so that there is more muscle that can do work.

This is exactly how metabolism can be altered or increased. What can be changed most readily, and what we have the most power over in our bodies, is the NREE.

To do this, muscles need anabolic power — the power to heal and build muscle mass. Anabolic power comes from eating healthy protein sources such as lean chicken, fish, beef, and eggs as well as dry beans, tofu, and dairy products.. It seems that older adults (> 60 years) need more protein than younger adults to build muscle mass, due to the body’s natural aging process which leads to sarcopenia. How much more? Studies show between 1.2 and 1.5 g/kg of body weight per day, whereas younger persons need 0.80 g/kg.

Developing sarcopenia with age involves muscle losing the ability to use protein and amino acids to rebuild injured tissue.

Let’s put this in perspective for treating obesity.

Obesity is brought on by the body’s defense of a higher body weight by interaction with the environment of highly processed foods that work on the reward pathway, leading to weight gain and resistance to satiety. Weight loss via diet, exercise, and medications works, but this weight loss is also accompanied by a decrease in TEE.

Weight loss is primarily fat mass loss, but depending on the degree of protein intake and muscle resistance training, 20%-50% of the total weight loss is muscle mass loss. Therefore, higher-protein diets and resistance exercise can be useful in preserving muscle mass and counteracting the decrease in TEE, maintaining energy expenditure. In older patients, an additional factor is the muscle’s lack of ability to use protein as an anabolic agent to protect muscle mass and thus the need for higher protein loads to do this.

All in all, can doctors help patients boost their metabolism, especially as they lose weight and maintain that loss? Yes — through protein intake and resistance exercise training.

Here are some tips to help your patients get cardio and resistance exercise into their routine.

First find out whether your patient prefers a social exercise interaction or solo training. If social, then the gym or classes such as cycling or boot camps at those gyms may work for them, especially if they can go with a friend. If solo is better, than a gym in the home might work. Peloton bikes are expensive but the interaction is all on the website!

A personal trainer may help motivate the patient if they know someone is waiting for them.

Let’s hit the gym!

Another note: There are agents in the obesity treatment pipeline that purport to change body composition while helping patients lose weight. Some of these agents are myostatin antagonists and antibodies that inhibit the activity of myostatin to break down muscle. These agents have been found to build muscle mass, but whether the quality of the muscle mass leads to an increase in muscle strength or functionality remains controversial. The next frontier in obesity treatment will be about decreasing fat mass and increasing muscle mass while making sure that increased muscle mass leads to improved functionality.

In the meantime, aside from new agents on the horizon, the best and healthiest way to keep metabolism on the up and up is to eat healthy lean proteins and exercise. How much exercise? The recommendation is 30-60 minutes of moderate to vigorous physical activity at least 5 days per week; plus 20 minutes of resistance exercise training 2-3 days per week for upper- and lower-extremity and core strength.

Again, let’s hit the gym!
 

Dr. Apovian is in the department of medicine, and codirector, Center for Weight Management and Wellness, Section of Endocrinology, Diabetes, and Hypertension, at Brigham and Women’s Hospital, Harvard Medical School, Boston. She disclosed ties with Altimmune, Cowen and Company, Currax Pharmaceuticals, EPG Communication Holdings, Gelesis, Srl, L-Nutra, and NeuroBo Pharmaceuticals, and Novo Nordisk. She received research grant from the National Institutes of Health, Patient-Centered Outcomes Research Institute, and GI Dynamics.

A version of this article appeared on Medscape.com.

Many patients with obesity blame weight gain on their metabolism. The reality is that metabolism can be blamed for weight regain after people try to lose weight! As we age, our metabolism does slow down; sometimes we think it stops working.

Metabolism, or resting energy expenditure, is directly related to how much muscle mass we have. As we age, we lose muscle, which is called sarcopenia.

What happens to our metabolism when we try to lose weight? Let’s first discuss what metabolism is.
 

What Is Metabolism?

Metabolism refers to the chemical reactions in the body’s cells that convert food into energy for sustaining life, cellular processes, and as storage for a rainy day.

Total energy expenditure (TEE) is broken down into resting energy expenditure (REE), thermic effect of food (TEF), and nonresting expenditure (NREE) or physical activity, and is made up of: TEE = 60% REE + 10% TEF + 30% NREE.

An elegant study performed by Dr. Rudy Leibel explored the effects of weight loss or weight gain on metabolism in 23 lean and 18 patients with obesity who were placed in a metabolic chamber. Weight loss of 10% or 20% body weight led to a decrease in TEE roughly equal to about 300 kcal/d, and an increase in body weight of 10% caused an increase in TEE of about 500 kcal/d. These changes led to the patient reverting to the prior weight (before weight loss or gain). In other words, Dr. Leibel postulated a feedback mechanism for the effect of fat mass decrease or increase on energy metabolism. The feedback mechanism or signal from fat was subsequently found to be leptin.

In a later study, Dr. Leibel and colleagues investigated the effects of body fat mass change on TEE and found that a 10% reduction in weight caused a decrease of TEE by 21%, comprising a decrease in NREE of 37.5% and a decrease in REE of 11.6%.

Therefore, the biggest change in TEE comes from NREE or exercise energy expenditure. The 35% variance in NEE change was accounted for by a decrease in muscle work efficiency in generating 10 watts or low levels of work such as walking.

In other words, when persons with obesity or lean persons lose weight, the efficiency of muscle at low levels of work increases such that one burns less energy when walking than one normally would. This helps conserve energy and tends to cause the body to go back to the higher weight.
 

So, How Can One Change Metabolism?

Let’s say one did lose weight and wants to counteract this TEE loss and increased muscle efficiency at low levels of work.

To counteract this effect, one should increase muscle work beyond low level so that more energy is expended. Another way would be to increase muscle mass so that there is more muscle that can do work.

This is exactly how metabolism can be altered or increased. What can be changed most readily, and what we have the most power over in our bodies, is the NREE.

To do this, muscles need anabolic power — the power to heal and build muscle mass. Anabolic power comes from eating healthy protein sources such as lean chicken, fish, beef, and eggs as well as dry beans, tofu, and dairy products.. It seems that older adults (> 60 years) need more protein than younger adults to build muscle mass, due to the body’s natural aging process which leads to sarcopenia. How much more? Studies show between 1.2 and 1.5 g/kg of body weight per day, whereas younger persons need 0.80 g/kg.

Developing sarcopenia with age involves muscle losing the ability to use protein and amino acids to rebuild injured tissue.

Let’s put this in perspective for treating obesity.

Obesity is brought on by the body’s defense of a higher body weight by interaction with the environment of highly processed foods that work on the reward pathway, leading to weight gain and resistance to satiety. Weight loss via diet, exercise, and medications works, but this weight loss is also accompanied by a decrease in TEE.

Weight loss is primarily fat mass loss, but depending on the degree of protein intake and muscle resistance training, 20%-50% of the total weight loss is muscle mass loss. Therefore, higher-protein diets and resistance exercise can be useful in preserving muscle mass and counteracting the decrease in TEE, maintaining energy expenditure. In older patients, an additional factor is the muscle’s lack of ability to use protein as an anabolic agent to protect muscle mass and thus the need for higher protein loads to do this.

All in all, can doctors help patients boost their metabolism, especially as they lose weight and maintain that loss? Yes — through protein intake and resistance exercise training.

Here are some tips to help your patients get cardio and resistance exercise into their routine.

First find out whether your patient prefers a social exercise interaction or solo training. If social, then the gym or classes such as cycling or boot camps at those gyms may work for them, especially if they can go with a friend. If solo is better, than a gym in the home might work. Peloton bikes are expensive but the interaction is all on the website!

A personal trainer may help motivate the patient if they know someone is waiting for them.

Let’s hit the gym!

Another note: There are agents in the obesity treatment pipeline that purport to change body composition while helping patients lose weight. Some of these agents are myostatin antagonists and antibodies that inhibit the activity of myostatin to break down muscle. These agents have been found to build muscle mass, but whether the quality of the muscle mass leads to an increase in muscle strength or functionality remains controversial. The next frontier in obesity treatment will be about decreasing fat mass and increasing muscle mass while making sure that increased muscle mass leads to improved functionality.

In the meantime, aside from new agents on the horizon, the best and healthiest way to keep metabolism on the up and up is to eat healthy lean proteins and exercise. How much exercise? The recommendation is 30-60 minutes of moderate to vigorous physical activity at least 5 days per week; plus 20 minutes of resistance exercise training 2-3 days per week for upper- and lower-extremity and core strength.

Again, let’s hit the gym!
 

Dr. Apovian is in the department of medicine, and codirector, Center for Weight Management and Wellness, Section of Endocrinology, Diabetes, and Hypertension, at Brigham and Women’s Hospital, Harvard Medical School, Boston. She disclosed ties with Altimmune, Cowen and Company, Currax Pharmaceuticals, EPG Communication Holdings, Gelesis, Srl, L-Nutra, and NeuroBo Pharmaceuticals, and Novo Nordisk. She received research grant from the National Institutes of Health, Patient-Centered Outcomes Research Institute, and GI Dynamics.

A version of this article appeared on Medscape.com.