Vitamin D and Cancer Rates in Postmenopausal Women

Vitamin D supplementation in women does not affect cancer rates in postmenopausal women, although the results of a recent study suggest more research is needed. In a four-year study from Nebraska, 2,303 healthy postmenopausal women were randomized to vitamin D3 2,000 IU/day along with calcium 1,500 mg/day or matching placebo. Vitamin D treatment raised serum levels from an average of 32.8 ng/mL to 43.9 ng/mL in the treatment group. A new cancer diagnosis was confirmed in 45 participants in the vitamin D/calcium group (3.89%) and 64 (5.58%) in the placebo group (difference, 1.69%; 95% CI, -0.06% to 3.46%; P = 0 .06), a nonsignificant difference. There were more kidney stones in the treatment group. The authors concluded that vitamin D plus calcium did not reduce cancer rates significantly, but more research is needed. (JAMA 2017;317:1234-1243)