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Calcium and Vitamin D Intake and Risk for Breast Cancer

Higher calcium and vitamin D intake showed modest benefit in premenopausal women.

Animal experiments and observational human studies suggest that calcium and vitamin D may decrease risk for breast cancer. Researchers prospectively assessed this relation among 10,000 premenopausal and 20,000 postmenopausal women enrolled in the Women’s Health Study. Calcium and vitamin D intake was determined from self-reported questionnaires about food and vitamin supplement intake.

During a mean follow-up of 10 years, the overall incidence of invasive breast cancer was 2.6% among premenopausal women and 3.6% among postmenopausal women. The hazard ratio for developing invasive breast cancer was 0.61 for premenopausal women at the highest versus lowest quintiles of calcium intake and 0.65 for vitamin D intake. No relation was found between calcium and vitamin D intake and risk for invasive breast cancer among postmenopausal women.

Comment: In this large, prospective study, a higher intake of calcium and vitamin D was associated with a lower risk for invasive breast cancer among premenopausal but not postmenopausal women. Although the hazard ratios appear relatively large, the absolute risk reduction was modest. Limitations of this study include ascertainment of calcium and vitamin D intake only once at baseline and the possibility that unmeasured confounding variables explain the findings in this nonrandomized assessment of diet.

— Jamaluddin Moloo, MD, MPH

Published in Journal Watch General Medicine June 14, 2007

Citation(s):

Lin J et al. Intakes of calcium and vitamin D and breast cancer risk in women. Arch Intern Med 2007 May 28; 167:1050-9.

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