Vitamin D supplement use associated with lower risk of breast cancer – ProHealth
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.