Meta-analysis supports calcium’s weight management potential
Every 1,000 milligram increase in calcium intake was associated with a statistically significant reduction in body weight of 0.076 kg, according to results published in the American Journal of Clinical Nutrition.
While no association was observed for calcium intake and waist circumference in the overall study cohort, the researchers did observe an association between calcium and lower waist circumference in people genetically predisposed to large waistlines.
Debate
The meta-analysis adds to the on-going debate on the potential role of calcium (and dairy) for weight management. A relationship between dairy intake and weight reduction has been reported in numerous studies, including a 2011 review published in Nutrition Reviews (Vol. 69, pp. 335-343). Scientists at the University of Exeter in the UK concluded that a daily dose of 1,000 milligrams of calcium was associated with a “small, significant reduction in body fat” of around 2 kg per year.
In addition, a meta-analysis in 2009 supported a causal relationship between calcium and fat loss.
One of the lead researchers in this area, Dr Michael Zemel from the University of Tennessee, has previously said that dairy can help reduce body fat and that calcium only accounts for about 40% of the effect.
The new meta-analysis indicates that genes may play a role in any association between calcium and waist circumference, but the authors stressed that this finding needs to be replication in additional studies.
Meta-analysis details
Led by Sofus Larsen from the Institute of Preventive Medicine at the Bispebjerg and Frederiksberg Hospitals in Copenhagen, the authors examined the relationship between diet, 54 single-nucleotide polymorphisms (SNPs), and BMI, waist circumference, or waist-hip ratio from 7,569 individuals from the three studies: the Danish Diet, Cancer and Health Study, the INTER99 study, and the MONItoring trends and determinants of CArdiovascular disease Study.
Results showed that a significant association was observed between body weight and increasing calcium intakes, but this was not linked to any SNPs. On the other hand, a significant interaction between calcium and six waist circumference-associated SNPs in relation to changes in waist circumference was observed.
Biological plausibility?
Commenting on the potential mechanism by which calcium beneficially impact body weight, the researchers said that calcium has been reported to bind insoluble soap in the diet and reduce the absorption of fat, and increase the excretion of fat in feces.
There are also suggestions that higher calcium levels may influence levels of the active form of vitamin D called 1,25-vitamin, which in turn results in lower intracellular concentrations of calcium. This is thought to stimulate the breakdown of fats (lipolysis) and inhibit the accumulation of fat in fat cells (adipocytes).
With respect to the potential genetic associations between calcium and waist circumference, the authors wrote: “It would be highly speculative to make suggestions about exactly what mechanisms might underlie the observed interaction between the developed score of 6 waist circumference -associated SNPs and calcium in relation to [the change in waist circumference], given the lack of knowledge about the mechanisms these genetic variants are involved in.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.113.076596
“Interaction between genetic predisposition to obesity and dietary calcium in relation to subsequent change in body weight and waist circumference”
Authors: S.C. Larsen, L. Angquist, T. Singh Ahluwalia, T. Skaaby, et al.
