Calcium Supplements May Raise Risk of Heart Attack

A new study has found that people who took calcium supplements had nearly double the risk of heart attack compared to those who do not take any dietary pills.

Researchers at the University of Zurich (Switzerland), the German Cancer Research Center (Heidelberg), and other institutions conducted a prospective study to evaluate the associations of dietary calcium intake and calcium supplementation with mitral infarct (MI), stroke risk, and overall cardiovascular disease (CVD) mortality. The researchers used data regarding 23,980 participants in the European Prospective Investigation into Cancer and Nutrition study, aged 35–64 years, who were free of major CVD events at recruitment. Calcium intake from diet was calculated from participants' food-frequency questionnaires filled out before enrollment, as well as if they were regularly taking dietary supplements.

The results showed that after 11 years of follow-up, the participants had suffered 354 MIs, 260 strokes, and 267 CVD related deaths. Associations for stroke risk and CVD mortality were overall null, but in comparison with non-users of any supplements, users of calcium supplements had a statistically significantly increased hazard risk (HR) for MI of 1.86; MI HR was even more pronounced for calcium supplement only users (2.39). The researchers also found that the source of calcium in the diet--dairy versus nondairy--did not affect risk of MI, stroke, or cardiovascular death very much. The study was published early online on May 23, 2012, in Heart.

“This study suggests that increasing dietary calcium intake from diet might not confer significant cardiovascular benefits, while calcium supplements, which might raise MI risk, should be taken with caution,” concluded lead author Sabine Rohrmann, MD, of the University of Zurich Institute of Social and Preventive Medicine.

Calcium supplements, which are commonly recommended to the elderly (particularly postmenopausal women) to maintain bone health and prevent osteoporosis, have also been suggested as beneficial agents to improve serum cholesterol profile and to control hypertension. However, no strong epidemiological evidence suggests that calcium supplementation might provide cardiovascular benefits.

Related Links:
University of Zurich
German Cancer Research Center