Effects of calcium supplementation on circulating lipids: potential pharmacoeconomic implications.

For about a century there has been recognition that calcium and lipids bind to one another in the gut, each interfering with the other's absorption. Calcium also causes malabsorption of bile acids, which is likely to contribute further to malabsorption of fat. High dietary calcium intakes may also have stimulatory effects on lipolysis. These mechanisms provide a basis for hypothesising that calcium supplementation may impact on circulating lipid concentrations, and there is now a significant amount of observational and trial data indicating that this is the case. The largest randomised controlled trial of calcium effects on lipids was carried out in 223 healthy postmenopausal women, and found that low density lipoprotein-cholesterol (LDL-C) decreased 6.3% and high density lipoprotein-cholesterol (HDL-C) increased by 7.3% at 1-year. The resultant 16.4% increase in HDL-C/LDL-C ratio would be predicted to reduce cardiovascular event rates by 20-30%, which is consistent with the available observational data. There are no trial data addressing this question and it is possible that other lipid-lowering agents, such as hydroxymethylglutaryl coenzyme A reductase inhibitors, might impact on cardiac event rates by mechanisms other than by lowering cholesterol levels. Therefore, caution is appropriate in incorporating these findings into clinical practice, but the balance of evidence suggests that calcium is a cost-effective adjunct to the dietary management of hyperlipidaemia.