For women aged 55 and older, there is a direct relationship between increasing blood levels of vitamin D and decreasing breast cancer risk.
Breast cancer risk markedly lower with serum 25-hydroxyvitamin D concentrations ≥60 vs <20 ng/ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort
Authors: McDonnell, S.L. et. al.
Source: PLOS doi.org/10.1371/journal.pone.0199265
Several studies have shown that vitamin D has beneficial effects against breast cancer. It protects breast cells from damage that may lead to cancer. It also promotes the death of breast cancer cells. While efforts are underway to find vitamin D-derived breast cancer treatments, actual prevention of the disease would be more beneficial.
The researchers’ goal was to determine if there is a relationship between a range of concentrations of vitamin D and breast cancer risk. They gathered data from three studies that evaluated women taking calcium and vitamin D. Almost 100% of these participants were white, and only women aged 55 or older were included.
Comparing the women with vitamin D levels ≥60 ng/ml compared to those with levels <20 ng/ml, the results were striking. The rate of breast cancer development was 82% lower. More women (99.3% vs. 96.8%) were free of breast cancer at four years. Finally, the group with the higher concentration had an 80% lower risk of developing breast cancer. All of these results persisted with the data was controlled for age, BMI, smoking status and calcium supplement intake. Moreover, for the intermediate concentrations of vitamin D (>20 and <60 ng/ml), the incidences and risks of breast cancer declined as the levels rose.
While only evaluating white women over age 55, this study nonetheless reinforces the concept that vitamin D has a protective effect against breast cancer. By describing actual blood concentrations, this data can help guide providers when counseling their patients about taking vitamin D. The researchers recommend further study to understand the effect of vitamin D among populations of color, as well as the effects of even higher vitamin D levels upon breast health.