Calcium Supplements May Increase Heart Attack Risk

Meta-analysis reveals significant increase in risk in those taking calcium versus those on placebo

31 july 2010-- Calcium supplementation is associated with an increased risk of myocardial infarction, according to a meta-analysis published online July 29 in BMJ.

Mark J. Bolland, Ph.D., of the University of Auckland in New Zealand, and colleagues searched the medical literature for randomized, placebo-controlled studies of calcium supplementation (500 or more mg/day) involving more than 100 subjects (mean age, over 40). The reviewers analyzed 15 studies with an aggregate of more than 20,000 subjects.

In five studies with patient level data, the investigators found that 143 subjects taking calcium had myocardial infarctions compared to 111 on placebo (hazard ratio, 1.31). There were also increases in risk for stroke; the composite end point of myocardial infarction, stroke, or sudden death; and all-cause mortality; however, these were considered nonsignificant. In a meta-analysis of trial level data, 166 subjects taking calcium had myocardial infarctions compared to 130 on placebo (pooled relative risk, 1.27).

"Calcium supplements (without coadministered vitamin D) are associated with an increased risk of myocardial infarction. 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. A reassessment of the role of calcium supplements in the management of osteoporosis is warranted," the authors write.

One study author disclosed receiving research support from and acting as a consultant for the dairy company Fonterra, while four authors reported receiving study drugs for clinical trials of calcium supplementation from pharmaceutical companies.

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