Recent study results suggest that supplementary vitamin D does not reduce the risk of breast cancer in postmenopausal women.
36,200 women involved in the Women’s Health Initiative (WHI) Study were assigned to take either 1000 mg of calcium and 400 IU of vitamin D each day or a placebo. The women were also allowed to take supplementary vitamin D if they wanted to regardless of whether they had been assigned to the treatment group or the placebo group.
Results showed that over the 7-year-long study period a similar number of women in both groups developed invasive breast cancer – 528 women assigned to take calcium and vitamin D, compared to 546 in the placebo group.
The authors concluded: “Although further study of relationships among calcium plus vitamin D supplement use and breast cancer can be considered, current evidence does not support their use in any dose to reduce breast cancer.”
Chlebowski RT, Johnson KC, Kooperberg C, et al. Calcium Plus Vitamin D Supplementation and the Risk of Breast Cancer. Journal of the National Cancer Institute. Advance access publised online November 11th 2008. doi:10.1093/jnci/djn360
