Is the cardiovascular risk of calcium supplementation exaggerated?

Calcium supplements may not increase the risk of cardiovascular disease (CVD) according to a recent study in Osteoporosis International.

Researchers at Brigham and Women’s Hospital performed a prospective cohort study of calcium supplement use and incident CVD in the 74,245 women in the Nurses’ Health Study who were free of CVD and cancer at baseline. Supplement intake was assessed every 4 years. Outcomes confirmed by medical review were stroke, either ischemic or hemorrhagic, and incident coronary heart disease (CHD), either nonfatal or fatal myocardial infarction.

In 24 years of follow-up, 4565 cardiovascular events were recorded, including 1856 strokes and 2709 CHD. The women who took calcium supplements had higher levels of physical activity, lower trans fat intake, and smoked less than their counterparts who did not take supplements. After adjusting for age, body mass index, dietary calcium, vitamin D intake, and other CVD risk factors, the relative risk (RR) of CVD for women taking >1000 mg/day of calcium compared with none was 0.82 (95% confidence interval [CI] 0.74 to 0.92; P<0.001). The RR for CHD in women who took >1000 mg/day of calcium supplements versus none was 0.71 (95% CI 0.61 to 0.83; P<0.001); for stroke, the RR was 1.03 (95% CI 0.87 to 1.21; P = 0.61). Relative risks were similar in analyses limited to women who had regular physical exams, women without hypertension, and non-smokers.

The investigators concluded that their findings did not support the hypothesis that calcium supplement intake leads to an increased risk of CVD in women.

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