?To the best of our knowledge, this is the first clinical trial in a population-based postmenopausal women cohort, to observe that increasing calcium intake, in the form of non-dairy calcium supplementation, can prevent gain of fat mass and loss of lean mass,? wrote the researchers, led by Lan-Juan Zhao from the Creighton University Medical Center in Omaha.
?The effect of calcium supplementation in this population-based cohort is consistent with the effect of dairy supplementation in fat and lean mass changes in obese subjects with low baseline calcium intake (< 600 mg/d),? they added.
Calcium or dairy?
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.
In order to examine if calcium supplements could affect obesity or body composition, Dr Zhao and her co-workers recruited 870 postmenopausal women with an average age of 66, an average BMI of 28.8 kg/m2. The women were randomly assigned to one of three groups: One group received two placebo capsules; the second group received calcium supplements and a placebo; and the final group received the calcium plus 1,100 IU of vitamin D3.
While no significant differences were observed for BMI between the groups, the calcium intervention groups were found to gain less trunk fat with increases of 2.4 and 1.4 percent in the calcium and calcium plus vitamin D groups, respectively, compared with the placebo group, where trunk fat increased by 5.4 per cent.
Moreover, the calcium-supplemented groups maintained their lean trunk mass to a greater extent than the placebo group, with reductions of 0.6 and 1 percent in the calcium and calcium plus vitamin D groups, respectively, compared with 2.1 percent in the placebo group.
The researchers noted that the habitual intake of the women before the trial was not low (average of over 1,000 millgrams per day). An earlier study from Canada indicated that the potential benefits of calcium supplements may be limited to women with low habitual intakes of the mineral (British Journal of Nutrition, 2009, Vol. 101, pp. 659-663).
Regarding the potential mechanism, the Canadian study proposed that calcium may affect appetite. Laval University researcher Angelo Tremblay stated: "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. Sufficient calcium intake seems to stifle the desire to eat more."
On the other hand, a meta-analysis published last year in Obesity Reviews (Vol. 10, pp. 475-486) indicated that calcium may aid weight management by increased fat excretion in the feces.
Source: Nutrition & Metabolism
?The effect of calcium and vitamin D supplementation on obesity in postmenopausal women: secondary analysis for a large-scale, placebo controlled, double-blind, 4-year longitudinal clinical trial?
Authors: J. Zhou, L-J. Zhao, P. Watson, Q. Zhang, J.M. Lappe