Does Vitamin D Reduce Breast Cancer Risks?

Breast cancer risks not affected by circulating vitamin D levels in most women

(RxWiki News) Vitamin D3 has been touted as possibly being able to help prevent certain cancers. The role of vitamin D in the prevention of breast cancer has had mixed reviews.

A new study shed more light on vitamin D supplements and breast cancer risks.

After analyzing data from two large studies and 10 previous studies, researchers concluded that vitamin D levels did not affect the breast cancer risks of most women.

There did, however, seem to be a modest association in women 45 years of age and younger, according to the researchers.

"Talk to your doctor about any supplement before you start taking it."

This review was led by Stephanie Scarmo, PhD, of the Department of Population Health at the New York University School of Medicine.

Researchers examined 10 different studies looking for an association between the blood levels of vitamin D - known as circulating 25(OH)D - and breast cancer risks.

We get vitamin D from food and the sun, as well as from vitamin D supplements.

Researchers analyzed the data of two long-term observational studies – the New York University Women’s Health Study (NYUWHS) with 14,274 participants and the Northern Sweden Mammary Screening Cohort (NSMSC), which involved 25,700 women.

Researchers collected blood samples from each woman when they entered the studies. The participants were followed for a number of years.

A total of 1,585 women diagnosed with breast cancer were matched with 2,940 healthy women.

Two blood samples, taken a year apart, were collected from 678 patients and 1,208 controls. Circulating levels of 25(OH)D were measured in each sample.

In addition to this data, the researchers looked at 10 previous studies - seven of which found no association and three of which found possible associations among women of specific ages.

“Circulating 25(OH)D levels were not associated with breast cancer risk overall, although we could not exclude the possibility of a protective effect in younger women [45 years old or younger]," the authors concluded. 

The authors also said, "Recommendations regarding vitamin D supplementation should be based on considerations other than breast cancer prevention.” 

This study was published February 28 in the journal Breast Cancer Research.

The study was supported by the National Cancer Institute and the National Institute of Environmental Health Sciences.No conflicts of interest were disclosed.

Review Date: 
March 5, 2013