Supplemental Calcium Fails to Prevent Weight Gain

BOSTON — Two years of treatment with supplemental calcium failed to significantly prevent weight gain in overweight, middle-aged adults, Dr. Jack Yanovski reported at the annual meeting of NAASO, the Obesity Society.

Multiple epidemiologic and observational studies have suggested that greater calcium intake is associated with less adiposity and reduced weight gain, but there have been no large clinical trials directly assessing the effects of calcium supplementation on body weight and composition.

To address the hypothesis of whether calcium can help prevent weight gain, a 2-year, double-blind trial randomized 340 healthy subjects to 1,500 mg calcium carbonate per day or placebo, said Dr. Yanovski, who heads the unit on growth and obesity in the Developmental Endocrinology Branch of the National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md.

Participants were informed that the study's purpose was to examine the health effects of calcium supplementation. They completed questionnaires every 3 months regarding their health and activities, and they were evaluated yearly for body weight and composition.

Mean age of the participants was 38.8 years, mean body mass index (BMI) was 33.4 kg/m

There were no baseline differences between the calcium and placebo groups in terms of age, BMI, sex, race, or reported dietary calcium intake, which was a mean of 882 mg/day. Roughly 23% of patients reported calcium intake that was extremely low, less than 600 mg/day, he said.

A total of 77% of patients in the calcium group completed the 2-year study, as did 71% of those in the placebo group, Dr. Yanovski said. Most of the noncompleters were lost to follow-up, and there were very few adverse effects.

“To assess blinding, we asked them if they thought they were receiving calcium or placebo, and somewhat to our surprise, almost two-thirds of both groups thought they were receiving placebo,” he said.

At the conclusion of the investigation, body weight had increased by a mean of 0.26 kg in the calcium group and by 0.96 kg in the placebo group, BMI had increased by 0.09 kg/m

None of these differences was statistically significant, he said.

Secondary analyses also found no differences in changes between males and females, among those with low baseline calcium intake, or between those classified as overweight or obese, he said.

“In summary, currently available data do not support the hypothesis that calcium supplementation is effective for avoiding weight gain or assisting in weight reduction,” Dr. Yanovski said.

A key proponent of the concept that calcium plays a role in obesity is Michael Zemel, Ph.D., of the University of Tennessee's Nutrition Institute, Knoxville. According to Dr. Zemel, the primary effect of dietary calcium on weight gain “appears to be inhibition of calcitrophic hormone effects on adipocyte energy storage and utilization,” (J. Am. Coll. Nutr. 2005;24[6 suppl.]:537S-46S).

Dr. Zemel also has emphasized the importance of dietary foods rather than supplements, explaining that dairy products contain bioactive compounds that may act synergistically with calcium to affect adipocyte metabolism.

The fact that Dr. Yanovski's study looked at calcium supplements instead of dietary calcium may have been a factor in its negative findings, an audience member suggested. Dr. Yanovski added that designing a randomized trial to look at dairy product consumption would be “very difficult to do in humans.”

BOSTON — Two years of treatment with supplemental calcium failed to significantly prevent weight gain in overweight, middle-aged adults, Dr. Jack Yanovski reported at the annual meeting of NAASO, the Obesity Society.

Multiple epidemiologic and observational studies have suggested that greater calcium intake is associated with less adiposity and reduced weight gain, but there have been no large clinical trials directly assessing the effects of calcium supplementation on body weight and composition.

To address the hypothesis of whether calcium can help prevent weight gain, a 2-year, double-blind trial randomized 340 healthy subjects to 1,500 mg calcium carbonate per day or placebo, said Dr. Yanovski, who heads the unit on growth and obesity in the Developmental Endocrinology Branch of the National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md.

Participants were informed that the study's purpose was to examine the health effects of calcium supplementation. They completed questionnaires every 3 months regarding their health and activities, and they were evaluated yearly for body weight and composition.

Mean age of the participants was 38.8 years, mean body mass index (BMI) was 33.4 kg/m

There were no baseline differences between the calcium and placebo groups in terms of age, BMI, sex, race, or reported dietary calcium intake, which was a mean of 882 mg/day. Roughly 23% of patients reported calcium intake that was extremely low, less than 600 mg/day, he said.

A total of 77% of patients in the calcium group completed the 2-year study, as did 71% of those in the placebo group, Dr. Yanovski said. Most of the noncompleters were lost to follow-up, and there were very few adverse effects.

“To assess blinding, we asked them if they thought they were receiving calcium or placebo, and somewhat to our surprise, almost two-thirds of both groups thought they were receiving placebo,” he said.

At the conclusion of the investigation, body weight had increased by a mean of 0.26 kg in the calcium group and by 0.96 kg in the placebo group, BMI had increased by 0.09 kg/m

None of these differences was statistically significant, he said.

Secondary analyses also found no differences in changes between males and females, among those with low baseline calcium intake, or between those classified as overweight or obese, he said.

“In summary, currently available data do not support the hypothesis that calcium supplementation is effective for avoiding weight gain or assisting in weight reduction,” Dr. Yanovski said.

A key proponent of the concept that calcium plays a role in obesity is Michael Zemel, Ph.D., of the University of Tennessee's Nutrition Institute, Knoxville. According to Dr. Zemel, the primary effect of dietary calcium on weight gain “appears to be inhibition of calcitrophic hormone effects on adipocyte energy storage and utilization,” (J. Am. Coll. Nutr. 2005;24[6 suppl.]:537S-46S).

Dr. Zemel also has emphasized the importance of dietary foods rather than supplements, explaining that dairy products contain bioactive compounds that may act synergistically with calcium to affect adipocyte metabolism.

The fact that Dr. Yanovski's study looked at calcium supplements instead of dietary calcium may have been a factor in its negative findings, an audience member suggested. Dr. Yanovski added that designing a randomized trial to look at dairy product consumption would be “very difficult to do in humans.”

BOSTON — Two years of treatment with supplemental calcium failed to significantly prevent weight gain in overweight, middle-aged adults, Dr. Jack Yanovski reported at the annual meeting of NAASO, the Obesity Society.

Multiple epidemiologic and observational studies have suggested that greater calcium intake is associated with less adiposity and reduced weight gain, but there have been no large clinical trials directly assessing the effects of calcium supplementation on body weight and composition.

To address the hypothesis of whether calcium can help prevent weight gain, a 2-year, double-blind trial randomized 340 healthy subjects to 1,500 mg calcium carbonate per day or placebo, said Dr. Yanovski, who heads the unit on growth and obesity in the Developmental Endocrinology Branch of the National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md.

Participants were informed that the study's purpose was to examine the health effects of calcium supplementation. They completed questionnaires every 3 months regarding their health and activities, and they were evaluated yearly for body weight and composition.

Mean age of the participants was 38.8 years, mean body mass index (BMI) was 33.4 kg/m

There were no baseline differences between the calcium and placebo groups in terms of age, BMI, sex, race, or reported dietary calcium intake, which was a mean of 882 mg/day. Roughly 23% of patients reported calcium intake that was extremely low, less than 600 mg/day, he said.

A total of 77% of patients in the calcium group completed the 2-year study, as did 71% of those in the placebo group, Dr. Yanovski said. Most of the noncompleters were lost to follow-up, and there were very few adverse effects.

“To assess blinding, we asked them if they thought they were receiving calcium or placebo, and somewhat to our surprise, almost two-thirds of both groups thought they were receiving placebo,” he said.

At the conclusion of the investigation, body weight had increased by a mean of 0.26 kg in the calcium group and by 0.96 kg in the placebo group, BMI had increased by 0.09 kg/m

None of these differences was statistically significant, he said.

Secondary analyses also found no differences in changes between males and females, among those with low baseline calcium intake, or between those classified as overweight or obese, he said.

“In summary, currently available data do not support the hypothesis that calcium supplementation is effective for avoiding weight gain or assisting in weight reduction,” Dr. Yanovski said.

A key proponent of the concept that calcium plays a role in obesity is Michael Zemel, Ph.D., of the University of Tennessee's Nutrition Institute, Knoxville. According to Dr. Zemel, the primary effect of dietary calcium on weight gain “appears to be inhibition of calcitrophic hormone effects on adipocyte energy storage and utilization,” (J. Am. Coll. Nutr. 2005;24[6 suppl.]:537S-46S).

Dr. Zemel also has emphasized the importance of dietary foods rather than supplements, explaining that dairy products contain bioactive compounds that may act synergistically with calcium to affect adipocyte metabolism.

The fact that Dr. Yanovski's study looked at calcium supplements instead of dietary calcium may have been a factor in its negative findings, an audience member suggested. Dr. Yanovski added that designing a randomized trial to look at dairy product consumption would be “very difficult to do in humans.”