High Levels of Vitamin D Appear to Protect Against Breast Cancer

Considerable evidence points to the important role of vitamin D in preventing breast cancer. But a new study suggests that high levels of vitamin D may be especially protective against estrogen-positive breast cancer, the most common type.

Kristina M. Blackmore, a research associate at Mount Sinai Hospital in Toronto, and her colleagues compared vitamin D levels in 759 women diagnosed with breast cancer and 1,135 women without the disease.

High vitamin D levels, from either sun exposure or dietary sources, were associated with a 24 percent lower risk of both estrogen-positive and progesterone-positive breast cancer. The growth of these types of breast cancer are stimulated by the hormones estrogen and progesterone.

Blackmore also found that high vitamin D levels were associated with a lower risk of estrogen- and progesterone-negative cancers, but the relationship was not as strong.

Reference: Blackmore KM, Lesosky M, Barnett H, et al. Vitamin D from dietary intake and sunlight exposure and the risk of hormone-receptor-defined breast cancer. American Journal of Epidemiology, 2008; doi 10.1093/aje/kwn198.