Reprinted with the kind permission of Life Extension.
July 24 2017. The July 2017 issue of Environmental Health Perspectives published the finding of researchers at the National Institutes of Health of a lower risk of breast cancer over five years of follow-up in association with higher levels of serum vitamin D or vitamin D supplementation.
The current investigation included participants in the Sister Study, which enrolled women with no history of breast cancer who had a sister diagnosed with the disease. Serum samples from 1,611 subjects who subsequently developed breast cancer and 1,775 randomly selected participants were analyzed for 25-hydroxyvitamin D levels [25(OH)D]. Average vitamin D intake and supplement use during the year prior to enrollment were estimated from data provided by questionnaire responses.
A serum 25(OH)D level of at least 38 nanograms per milliliter (ng/mL) was associated with a 21% lower adjusted risk of developing breast cancer over follow-up in comparison with levels of 24.6 ng/mL or less. The use of a vitamin D supplement at least four times per week was associated with an 11% lower risk of the disease, which declined to a 17% lower risk among postmenopausal women.
“To date, the randomized clinical trials of vitamin D supplementation have provided little evidence of benefit from supplementation,” the authors remark. “However, certain features, including small sample size, nonadherence, and combined treatment regimens or off-protocol supplementation made it difficult for those trials to establish causality or to identify effective dose levels. In principle, a randomized, placebo-controlled trial of vitamin D supplements alone among women who abstain from self-supplementation would be the best way to assess the effects of vitamin D on breast cancer risk.”
“Our results support the hypothesis that vitamin D supplementation could be effective for breast cancer prevention and may help to establish clinical benchmarks for beneficial 25(OH)D levels,” they conclude.