Men's Osteoporosis Support Group

Calcium supplements and myocardial infarction

BMJ. 2010 Jul 29;341:c3691. doi: 10.1136/bmj.c3691. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. Bolland MJ and others. PMID: 20671013. There is also free full text for this article. This study was a meta-analysis that included several controlled clinical trials of individuals taking calcium supplements as part of their medication regimen for osteoporosis. The study found, "In the five studies contributing patient level data, 143 people allocated to calcium had a myocardial infarction compared with 111 allocated to placebo (hazard ratio 1.31, 95% confidence interval 1.02 to 1.67, P=0.035)." So this is a 31% higher risk for myocardial infarction in the calcium supplement group compared to placebo. The authors concluded, "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." [Bold text added by the editor].

Editor's comments: The full-text article explains possible reasons for increased cardiovascular risk, "Calcium supplements acutely increase serum calcium levels to a modest degree. Serum calcium levels have been positively associated with an increased incidence of myocardial infarction in large observational studies. Primary hyperparathyroidism, a condition in which serum calcium levels are raised, has also been associated with an increased risk of cardiovascular events and death." They also state, "Our graphical data are consistent with the possibility that an increased risk of myocardial infarction with calcium supplements emerges quickly, pointing to mechanisms such as increased coagulability or altered vascular flow, perhaps mediated directly through the calcium sensing receptor or indirectly through alterations in calcitropic hormones." They also suggest that, "Incorporating the results from the current analysis of studies contributing patient level data, treatment of 1000 people with calcium for five years would cause an additional 14 myocardial infarctions, 10 strokes, and 13 deaths, and prevent 26 fractures."

Note that this study doesn't include individuals who take vitamin D supplements with their calcium, so, at least for now, that is not a known risk factor. And, I would expect that most individuals taking osteoporosis medication would be taking a combination of calcium and vitamin D supplements. If you aren't doing so, this meta-analysis suggests that you would be on the safe side to take both calcium and vitamin D, and not take only calcium supplements.

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