Effect of 5 y of calcium plus vitamin D supplementation on change in circulating lipids: results from the Women's Health Initiative

Background: Dietary calcium and vitamin D intakes may be inversely associated with cardiovascular disease (CVD) risk, possibly because of their potential beneficial effects on circulating lipids. Clinical trials that have evaluated the effect of calcium supplementation on lipids are limited by a short follow-up, and data on vitamin D are scarce. Objective: The objective was to evaluate the effect of a longer-term effect (over 5 y) of calcium and vitamin D (CaD) supplementation on changes in the concentrations of several lipids: LDL, HDL, non-HDL, total cholesterol, triglycerides, and lipoprotein(a) [Lp(a)]. Design: The study was conducted in 1259 postmenopausal women in the Calcium plus Vitamin D Trial (1 g elemental Ca as carbonate plus 400 IU vitamin D-3/d compared with placebo) of the Women's Health Initiative. Analyses were conducted by intention-to-treat. Repeated measurements on lipids during follow-up were analyzed by linear mixed-effects models. Results: Overall, the change in lipids was relatively small [<= 5% except for Lp(a), which was 20-25%], and there was no significant difference in the mean change of any lipid variable between the active and placebo groups. Conclusions: Our results indicate that CaD supplementation is not associated with lipid changes over 5 y. Existing and future CaD trials should consider evaluating this association for different doses of supplements. This study was registered at clinicaltrials.gov as NCT00000611. Am J Clin Nutr 2010; 91: 894-9.