Calcium from dairy sources, but not supplements, decreased excess levels of fat in the blood after eating, says research from Denmark that is yet another twist to the calcium-dairy weight loss debate.
The study, published in the American Journal of Clinical Nutrition, reports that triacylglycerol levels in the blood (the major fat form in the blood after absortpion) were between 15 and 19 per cent lower amongst subjects consuming a dairy source of calcium than subjects receiving calcium carbonate supplements.
"As far as we know, the present study is the first to show that an increased calcium intake from dairy products exerts a lowering effect on postprandial fat absorption," wrote lead author Janne Kunchel Lorenzen from the University of Copenhagen.
Lorenzen and co-workers recruited 18 subjects (average age 25.7, average BMI 27.1 kg per sq. m) and randomly assigned them to consume test meals containing high (HC meal: 172 mg/MJ), medium (MC meal: 84 mg/MJ), or low (LC meal: 15 mg/MJ) amounts of calcium from dairy or a high amount of supplemental calcium (S meal: 183 mg/MJ)in the form of calcium carbonate, in a cross-over design. All subjects consumed the four test meals.
The researchers report that consumption of dairy calcium significantly decreased the postprandial lipid response by 17 and 19 per cent after the MC meal the HC meal, respectively, compared to the LC meal, and 15 and 17 per cent after the MC meal and the HC meal, respectively, than after the S meal.
No statistically significant changes in appetite sensation, or on energy intake at the subsequent meal, between either source of calcium, they said.
"Increased calcium intakes from dairy products attenuate postprandial lipidemia, most probably because of reduced fat absorption, whereas supplementary calcium carbonate does not exert such an effect," stated the researcher.
The researchers suggest that the form of the calcium may play an important role in the effects observed, with dairy calcium found mostly in the form of calcium phosphate. Previous studies have suggested that calcium phosphate may bind to bile acids and partially inhibit the formation of micelles that transport the fat from the intestine to the blood stream.
The researchers called for further studies to re-examine these conclusions.
Last year, Dr. Michael Zemel from the University of Tennessee told attendees at the Paris Anti-Obesity Therapies 2006 conference that dairy can help reduce body fat and that calcium only accounts for about 40 per cent of the effect.
Dairy industries in Europe and the US have been promoting milk-based products for consumers who want to slim for some time but the new findings underline that further work needs to be done to support such claims.
Source: American Journal of Clinical Nutrition
March 2007, Volume 85, Number 3, Pages 678-687
"Effect of dairy calcium or supplementary calcium intake on postprandial fat metabolism, appetite, and subsequent energy intake"
Authors: J.K. Lorenzen, S. Nielsen, J.J. Holst, I. Tetens, J.F. Rehfeld and A. Astrup