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Calcium Supplementation Is Associated with Excess Risk for Myocardial Infarction
Marginal-to-moderate bone benefits must be weighed against cardiovascular risks.

Evidence suggests that calcium supplements hasten vascular calcification and increase mortality in patients with kidney failure and raise risk for myocardial infarction (MI) in healthy older women. To further investigate the association between supplemental calcium and adverse cardiovascular events, researchers conducted a meta-analysis of 15 double-blind, randomized trials in which participants (mean age at baseline, >40) received calcium supplements (>/= 500 mg daily) or placebo.

Patient-level data were available for five trials involving >8000 participants (77% women; median follow-up, 3.6 years). MIs occurred in 143 participants randomized to calcium supplements and 111 randomized to placebo — a significant difference. Calcium supplementation was not associated with excess risk for stroke or death. Analyses of trial-level data, involving 11 studies with nearly 12,000 patients, yielded findings similar to those that were based on patient-level data.

Comment:
Calcium supplementation is associated with excess risk for MI. Clinicians should weigh this risk against the marginal-to-modest benefits of calcium supplementation on bone density and fracture risk. Based on current data, the authors estimate that treating 1000 people with calcium supplements for 5 years would prevent only 26 fractures but would cause an additional 14 MIs.

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Paul S. Mueller, MD, MPH, FACP
Published in Journal Watch General Medicine August 31, 2010

Citation(s):
Bolland MJ et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: Meta-analysis. BMJ 2010 Jul 29; 341:c3691. (http://dx.doi.org/10.1136/bmj.c3691)