Calcium supplements may raise MI risk

Calcium supplementation is associated with an increased risk of myocardial infarction (MI), according to a meta-analysis published online July 29 in BMJ and reported by HealthDay News.

Mark J. Bolland, PhD, 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, >40 years). The reviewers analyzed 15 studies with an aggregate of more than 20,000 subjects.

In 5 studies with patient level data, the investigators found that 143 subjects taking calcium had MIs compared with 111 on placebo (hazard ratio, 1.31). There were also increases in risk for stroke; the composite end point of MI, 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 MIs compared with 130 on placebo (pooled relative risk, 1.27).

“Calcium supplements (without co-administered vitamin D) are associated with an increased risk of myocardial infarction,” the authors wrote. “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.”

One study author disclosed receiving research support from and acting as a consultant for the dairy company Fonterra, while 4 authors reported receiving study drugs for clinical trials of calcium supplementation from pharmaceutical companies.