Effects of Calcium Supplementation on Body Weight and Blood Pressure in Normal Older Women: A Randomized Controlled Trial

Abstract

Abstract Context: Epidemiological data suggest that high calcium intakes are associated with decreased body weight and blood pressure. However, there is little evidence from randomized trials that addresses these important issues. Objective: The objective of this study was to assess the long-term effects of calcium on body weight and blood pressure. Design: This is a substudy of an ongoing, double-blind, randomized, controlled trial of calcium supplementation. End points were assessed at 30 months. Setting: This study was performed at a university medical center. Participants: Normal postmenopausal women (mean age, 74 yr; mean weight, 67 kg; mean blood pressure, 134/70 mm Hg at baseline) participated in this study. Intervention: Study subjects were treated with calcium (1 g/d; n = 732) and placebo (n = 739). Main Outcome Measures: Body weight and blood pressure were the main outcome measures. Results: Weight decreased by 368 ± 132 g (mean ± se) with calcium treatment and by 369 ± 134 g with placebo (P = 0.93). Fat and lean masses did not show an effect of calcium. Blood pressure showed transient reductions of 1–2 mm Hg at 6 months in the calcium group, resulting in a significant between-group difference only for systolic pressure (P = 0.048). At 30 months, the change from baseline in systolic pressure was 0.0 ± 0.9 mm Hg in the calcium group and 2.4 ± 0.9 mm Hg in the placebo group (P = 0.14). For diastolic pressures, the changes were −0.2 ± 0.4 and 0.8 ± 0.4 mm Hg, respectively (P = 0.13). In those with baseline calcium intakes less than 600 mg/d, the treatment effect was greater and did persist. Conclusions: Calcium supplementation of 1 g/d does not produce biologically significant effects on body weight, and its hypotensive effect is small and transient in most women.