Writing in the British Journal of Nutrition, researchers from the Université Laval report that additional calcium from a supplement affected appetite in obese women with average daily calcium intakes of less than 600 milligrams.
"Our hypothesis is that the brain can detect the lack of calcium and seeks to compensate by spurring food intake, which obviously works against the goals of any weight loss program," said lead researcher Angelo Tremblay. "Sufficient calcium intake seems to stifle the desire to eat more."
The study adds to an ever growing body of science linking calcium intake, mainly from dairy products, in weight loss. The topic is a source of controversy with both camps able to quote research that supports their side and undermines the other.
Over 300m adults are obese worldwide, according to latest statistics from the WHO and the International Obesity Task Force. About one-quarter of the US adult population is said to be obese, with rates in Western Europe on the rise, although not yet at similar levels.
Tremblay and his co-workers recruited 63 overweight and obese women (average age 43, average BMI 32 kg/m2) and assigned them to a 15-week weight-reducing programme supplemented with either a daily calcium plus vitamin D supplement (1200 mg calcium and 10 micrograms vitamin D), or placebo.
All the women had daily calcium intakes of less than 800 mg.
At the end of the study, the researchers reported that the calcium plus vitamin D supplements had no statistically significant improvement in fat loss, relative to placebo.
However, when the researchers limited their analysis to women with very low-calcium intakes, defined as less that 600 milligrams, they found that weight loss was almost 6 kg, compared to 1 kg for women in the control group.
The change in the women’s fat mass was related to a change in lipid intake, they added.
“We propose that this change in lipid intake could be influenced by a calcium-specific appetite control,” wrote the researchers.
Dr Tremblay added that sufficient calcium consumption is therefore important to ensuring the success of any weight loss program. Over 50% of obese women who come to the clinic run by his research team do not consume the recommended daily intake, he added.
Calcium and vitamin D are key performers in the dietary supplements industry, with calcium reported to be the biggest seller in the US supplements industry. Annual sales amounted to about $993m (€836m) in 2004, according to the Nutrition Business Journal.
Source: British Journal of Nutrition Mar 2009, Volume 101, Issue 05, Pages 659-663, doi: 10.1017/S0007114508030808“Calcium plus vitamin D supplementation and fat mass loss in female very low-calcium consumers: potential link with a calcium-specific appetite control” Authors: G.C. Major, F.P. Alarie, J. Dor, A. Tremblay