That finding, published in the June 16 issue of the Annals of Internal Medicine, comes from a two-year study of 340 overweight or obese adults in the Washington, D.C., area.
Participants were about 39 years old, on average; most were women. They volunteered for a study about the health effects of calcium but weren't told that it was about weight.
Participants took 1,500 milligrams of either calcium carbonate or a placebo daily for two years, without knowing whether they were taking calcium or the placebo. They weren't asked to diet or exercise for the study.
At the end of the study, participants had gained nearly 3 pounds and 1.8 pounds of fat mass, on average. There were no differences in weight gain or fat mass gain in patients taking calcium compared to those taking the placebo. No side effects were related to calcium supplements.
"Even though there may be other important reasons, such as fracture prevention, to recommend dietary calcium supplementation, we conclude that the extant data suggest that calcium supplementation is unlikely to have clinically significant efficacy as a preventive measure against weight gain in persons who are already overweight or obese," write the researchers, who included Jack Yanovski, MD, PhD, of the National Institutes of Health (NIH).
Supplements Industry Responds
In the statement, Douglas MacKay, ND, vice president for scientific and regulatory affairs at the council, says if the study had also included overweight and obese adults who were assigned to follow a healthy diet and to exercise -- with or without calcium supplements -- "perhaps we would have seen very different results."
MacKay also notes that studies have shown that most Americans don't get enough calcium, especially if they're on low-calorie diets.
"Despite the results of this study, American adults, particularly those who are consuming low-calorie diets, should continue to feel confident in the many benefits that calcium supplements provide. The overwhelming body of evidence suggests that adults still need 1,000-1,500 mg of calcium daily (combined from whole foods as well as supplements) and this study does nothing to change that," MacKay says.