In a predominantly premenopausal population, Eliassen and colleagues evaluated plasma vitamin D levels (25-hydroxyvitamin D) and risk of invasive breast cancer (see article).
During up to 10 years of follow-up after blood samples were collected some 613 cases of breast cancer were confirmed in this cohort. In a detailed analysis that accounted for breast cancer risk factors and many of the issues surrounding blood vitamin D levels (such as season of blood collection, age, and levels of obesity) the authors found no evidence for a protective association. In fact, risk tended to increase with higher vitamin D levels. Risk did not vary for ER positive or ER negative tumors.
Overall, these prospective data do not support any protective benefit for higher vitamin D levels against breast cancer among premenopausal women.
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