Supplementation Had No Impact on Fat Metabolism
In a rigorously designed study to examine the issue, investigators found no evidence that calcium supplementation influenced energy expenditure or fat-burning in overweight people whose regular diets were deficient in the mineral.
Widely publicized animal and human studies that did suggest a role for calcium in weight loss led to a multimillion dollar ad campaign promoting three servings of dairy products a day with slogans like "Milk your diet. Lose weight!"
The new study was conducted in an effort to confirm or disprove the findings in these earlier studies, metabolic physiologist Hilary Green, PhD, of Nestle, tells WebMD.
"There was no evidence in this latest research to suggest that calcium helps people burn more fat through the mechanisms that were tested," she says.
Calcium and Weight Loss
The 20-week study, conducted by researchers from Switzerland's University of Lausanne and the Nestle Research Center, included 10 overweight or obese people identified before recruitment whose regular diets were low in calcium.
Study participants were randomly assigned to be given either placebo or 800 milligrams of dairy calcium daily for two five-week periods, separated by a 10-week washout phase.
Four weeks into the supplementation phases of the study, researchers performed a battery of tests designed to examine the impact of calcium on fat metabolism.
The tests revealed no differences between the people taking the placebo and the calcium in any of these measures, including resting energy expenditure, fat oxidation, and plasma-free fatty acid concentrations.
In addition, expression of seven key metabolic genes in biopsied fat tissue was not affected by calcium supplementation.
In an accompanying editorial, University of Copenhagen nutrition researcher Arne Astrup, MD, writes that the study makes a strong case against the hypothesis that calcium-controlled pathways in fat tissue help regulate body weight.
But he concludes that there is still good evidence indicating a role for dietary calcium in weight regulation.
The study and editorial appear in the October issue of the American Journal of Clinical Nutrition.