Calcium supplement intake and risk of cardiovascular disease in women
Some recent reports suggest that calcium supplement use may increase risk of cardiovascular disease. In a prospective cohort study of 74,245 women in the Nurses' Health Study with 24 years of follow-up, we found no independent associations between supplemental calcium intake and risk of incident coronary heart disease (CHD) and stroke.
Some recent reports suggest that calcium supplements may increase cardiovascular disease (CVD) risk. The objective was to examine the independent associations between calcium supplement use and risk of CVD.
We conducted a prospective cohort study of supplemental calcium use and incident CVD in 74,245 women in the Nurses' Health Study (1984–2008) free of CVD and cancer at baseline. Calcium supplement intake was assessed every 4 years. Outcomes were incident CHD (nonfatal or fatal MI) and stroke (ischemic or hemorrhagic), confirmed by medical record review.
During 24 years of follow-up, 4,565 cardiovascular events occurred (2,709 CHD and 1,856 strokes). At baseline, women who took calcium supplements had higher levels of physical activity, smoked less, and had lower trans fat intake compared with those who did not take calcium supplements. After multivariable adjustment for age, body mass index, dietary calcium, vitamin D intake, and other CVD risk factors, the relative risk of CVD for women taking >1,000 mg/day of calcium supplements compared with none was 0.82 (95 % confidence interval [CI] 0.74 to 0.92; p for trend <0.001). For women taking >1,000 mg/day of calcium supplements compared with none, the multivariable-adjusted relative risk for CHD was 0.71 (0.61 to 0.83; p for trend < 0.001) and for stroke was 1.03 (0.87 to 1.21; p for trend = 0.61). The relative risks were similar in analyses limited to non-smokers, women without hypertension, and women who had regular physical exams.
Our findings do not support the hypothesis that calcium supplement intake increases CVD risk in women.
KeywordsCalcium supplements Cardiovascular disease Coronary heart disease Prospective study Stroke
We are indebted to the participants in the Nurses’ Health Study for their continuing cooperation. Funding. This research was supported by the National Institutes of Health grants HL092947, HL34594, HL088521, DK091417, CA087969 and DK100447.
Conflicts of interest
Julie M. Paik, Gary C. Curhan, Qi Sun, Kathryn M. Rexrode, JoAnn E. Manson, Eric B. Rimm, and Eric N. Taylor declare that they have no conflicts of interest. The authors declare no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.
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