People who take calcium supplements without coadministered vitamin D may be increasing their risk for heart attack by as much as 31%, based on the findings of a recent meta-analysis.

Many take calcium supplements to prevent or treat osteoporosis. But these products may increase the risk of cardiovascular events in healthy older women, prompting researchers to evaluate evidence from several randomized controlled trials of calcium supplements (>500 mg/day).

In five studies, 143 people taking calcium supplements suffered a heart attack, compared with 111 given a placebo, representing a 31% increased risk for MI. Nonsignficant increases were also seen in the incidence of stroke and in the composite end point of heart attack, stroke, or sudden death. Similar results were seen in 11 other trials, in which 166 supplement users and 130 placebo-takers had heart attacks.

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“As calcium supplements are widely used, these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population,” investigators noted (BMJ. 2010;341:c3691; available at, accessed September 15, 2010). “A reassessment of the role of calcium supplements in the study management of osteoporosis is warranted.”

Data suggest that these cardiovascular risks are associated only with calcium-supplement use, not dietary calcium intake. n