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Cardiovascular Risk and Calcium Supplementation in Postmenopausal Women

Calcium supplementation might raise, rather than lower, cardiovascular risk in postmenopausal women.

In a previous randomized trial, researchers found that calcium citrate supplementation favorably altered blood lipids in postmenopausal women (Am J Med 2002; 112:343). Furthermore, observational studies have shown that postmenopausal women who have high calcium intakes experienced fewer adverse cardiovascular events and deaths than did women with low calcium intakes. However, prospective data are lacking.

New Zealand investigators randomized 1471 postmenopausal women (mean age, 74) to daily calcium citrate (1 g) or placebo. Study participants and their family members reported adverse cardiovascular events, which were verified by medical record reviews. After 5 years, 21 women in the calcium group had experienced 24 myocardial infarctions, whereas 10 women in the placebo group experienced 10 MIs (P=0.047). However, no between-group differences were observed in stroke, sudden death, or a composite of the three endpoints. When events that were not reported by the participants or families but were found in a national database were added to the analysis, no differences were noted in the individual endpoints or in the composite endpoint. However, the incidence of the composite endpoint in the calcium group (23.3/1000 person-years) was higher than the rate in the placebo group (16.3/1000 person-years; P=0.043).

Comment: The results of this study suggest that calcium supplementation does not lower cardiovascular risk in postmenopausal women but, instead, could raise it. However, the few differences between the calcium and placebo groups barely achieved statistical significance. Until larger prospective trials are conducted to establish the true cardiovascular risk, if any, of calcium supplementation in these patients, clinicians should weigh these possible risks against the presumed beneficial role of calcium in preventing osteoporosis.

— Paul S. Mueller, MD, MPH, FACP

Dr. Mueller is an Associate Professor of Medicine in the Division of General Internal Medicine at Mayo Clinic in Rochester, Minnesota.

Published in Journal Watch General Medicine February 19, 2008

Citation(s):

Bolland MJ et al. Vascular events in healthy older women receiving calcium supplementation: Randomised controlled trial. BMJ 2008 Feb 2; 336:262.

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