Effects of calcium supplementation on body weight and blood pressure in normal older women: a randomized controlled trial.

Abstract

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. The objective of this study was to assess the long-term effects of calcium on body weight and blood pressure. This is a substudy of an ongoing, double-blind, randomized, controlled trial of calcium supplementation. End points were assessed at 30 months. This study was performed at a university medical center. Normal postmenopausal women (mean age, 74 yr; mean weight, 67 kg; mean blood pressure, 134/70 mm Hg at baseline) participated in this study. Study subjects were treated with calcium (1 g/d; n = 732) and placebo (n = 739). Body weight and blood pressure were the main outcome measures. 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. 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.