A combination of calcium plus vitamin D during weight loss in overweight and obese women could improve blood cholesterol levels, says new research from Canada.
Researchers from the University of Laval recruited 63 women with an average BMI of kg per sq. m. and assigned them to either a daily calcium (600 mg) plus vitamin D (200 IU) supplement or placebo for 15 weeks.
Calcium, from supplements or dairy, has been linked to weight loss amongst various population groups, but the area remains controversial and results inconsistent. Indeed, two studies from Purdue University reported conflicting claims, with one reporting that young women could burn more calories if they ate three or four dairy servings per day, while the other reported that increased dairy consumption had no effect on weight gain or loss.
A study last year, published in the Journal of the American Dietetic Association (Vol. 106, pp. 1066-1073), brought the focus of the debate back to calcium with the researchers concluding that calcium, in the form of supplements, could be beneficial for weight control, but only in women.
The new study, published in the current issue of the American Journal of Clinical Nutrition, lead author Geneviève Major from the Department of Social and Preventive Medicine at the university's Faculty of Medicine reports that the combination of the vitamin and calcium may improve cholesterol levels during weight loss.
The randomised, double-blind controlled trial recruited 63 women with daily calcium intakes less than 800 milligrams per day, which is the EU recommended daily intake (RDI). They were assigned to either the calcium plus vitamin D group or placebo, with both groups adhering to a weight loss plan whereby their energy intake was restricted by 700 kcal per day.
After 15 weeks of supplementation the researchers report that the calcium supplements significantly improved the total:HDL cholesterol ratio, reported to be the most specific lipid risk factor for CVD. Improvements in the ration of LDL (so-called 'bad' cholesterol) to HDL (so-called 'good' cholesterol) also improved. The improvements in blood lipid levels were independent of fat mass and waist circumference, they said.
"A tendency for more beneficial changes in HDL cholesterol, triacylglycerol, and total cholesterol was also observed in the calcium + [vitamin] D group," said the researchers.
Professor Angelo was not available for comment prior to publication, but told Reuters Health that a number of mechanisms may be behind the apparent effects, including the role of calcium to interfere with fat absorption in the gut, boosting the body's ability to burn fat, or potentially having a satiety role.
"Consumption of calcium + D during a weight-loss intervention enhanced the beneficial effect of body weight loss on the lipid and lipoprotein profile in overweight or obese women with usual low daily calcium intake," concluded the researchers.
Use of these supplements is widely accepted by the general public, with calcium reported to be the biggest seller in the US supplements industry. Annual sales were about $993m (€836m) in 2004, according to the Nutrition Business Journal.
The combination of vitamin D and calcium has long been recommended to reduce the risk of bone fracture for older people, particularly those at risk of or suffering from osteoporosis, which is estimated to affect about 75m people in Europe, USA and Japan.
Source: American Journal of Clinical Nutrition
January 2007, Volume 85, Number 1, Pages 54-59
"Supplementation with calcium + vitamin D enhances the beneficial effect of weight loss on plasma lipid and lipoprotein concentrations"
Authors: G.C. Major, F. Alarie, J. Doré, S. Phouttama and A. Tremblay