Calcium supplements may increase cardiovascular risk

Calcium supplements may increase risk for cardiovascular events in patients with or at risk for osteoporosis, a new study reports.

Researchers performed a meta-analysis of randomized, placebo-controlled trials that looked at use of calcium supplements of at least 500 mg/d in patients older than age 40. Trials that examined calcium supplementation plus vitamin D were excluded. Primary end points were time to first myocardial infarction (MI), first stroke, and first composite end point event (MI, stroke or sudden death). All-cause mortality was the secondary end point. The study was published online July 29 by BMJ.

Fifteen trials involving more than 12,000 patients were included in the study. Of these trials, five had patient-level data and 11 had trial-level data. In the patient-level data, the hazard ratio for MI was 1.31 (95% CI, 1.02 to 1.67; P=0.035) for patients who took calcium versus those who took placebo, and incidence of stroke, the composite end point, and all-cause mortality saw nonsignificant increases in this group. In the trial-level data, the pooled relative risk for MI associated with calcium supplementation was 1.27 (95% CI, 1.01 to 1.59; P=0.038).

The authors noted that their results cannot be generalized to include calcium supplementation plus vitamin D and that the included trials did not use cardiovascular outcomes as primary end points. However, they concluded that calcium supplements are associated with an increased MI risk that could translate to a substantial disease burden, given their widespread use. The role of calcium supplements in osteoporosis management should be reassessed, the authors said.

An accompanying editorial noted that since the benefits of calcium supplements are not definitively proven, any risk associated with their use is not warranted. "On the basis of the limited evidence available, patients with osteoporosis should generally not be treated with calcium supplements, either alone or combined with vitamin D, unless they are also receiving an effective treatment for osteoporosis for a recognized indication," the editorialists concluded.