A new study from Brazil corroborates the evidence gathered by previous research, suggesting that women with low levels of vitamin D after menopause onset have a higher risk of developing breast cancer.

The National Cancer Institute (NCI) note that "approximately 12.4% of women will be diagnosed with female breast cancer at some point during their lifetime."

Worldwide, breast cancer is the most commonly diagnosed form of cancer in women.

Some of the main risk factors for breast cancer include being a woman, advancing age, and obesity after menopause.

Over the past few years, many studies have also been discussing the importance and potential impact of vitamin D in relation to breast cancer risk.

For instance, one such study—covered by Medical News Today earlier this year—that worked with a cohort of participants from Japan found that the women with the highest levels of vitamin D in their system had a significantly lower risk of cancer, compared with those with the lowest vitamin D levels.

Now, researchers at the Sao Paulo State University in Brazil have reached similar conclusions after analyzing the medical data of 627 Brazilian women aged 45–75.

Their findings are reported in a study paper—the first author of which is Dr. Murilo Renato Matos Machado—that appears in the journal Menopause, of the North American Menopause Society (NAMS).

'Vitamin D may stop cancer cell growth'

These participants consisted of two groups of women: 209 diagosed with breast cancer, plus 418 cancer-free women who acted as the control group. All the participants had to have stopped menstruating for at least 12 months.

Comparing the medical information collected from the two groups of women, the researchers note that, at the time of diagnosis, the women with breast cancer had higher rates of low or very low serum (blood) vitamin D, compared with their cancer-free counterparts.

Also, a larger number of the women who had breast cancer had a high BMI or obesity, compared with the participants without breast cancer.

Finally, in conducting risk analysis—wherein the team adjusted for relevant modifying factors, such as age, BMI, and time from menopause onset—they concluded that women with breast cancer had a 1.5-fold higher risk than women without cancer to develop low vitamin D levels.

The authors hypothesize that appropriate levels of vitamin D in the system might help lower the risk of cancer by hindering cell proliferation.

According to Dr. JoAnn Pinkerton, the executive director of NAMS, "Although published literature is inconsistent about the benefits of vitamin D levels [in] breast cancer, this study and others suggest that higher levels of vitamin D in the body are associated with lowered breast cancer risk."

"Vitamin D may play a role in controlling breast cancer cells or stopping them from growing. Vitamin D comes from direct sunlight exposure, vitamin D3 supplements, or foods rich in vitamin D."

–Dr. JoAnn Pinkerton

Some foods with a high content of vitamin D, and that people may want to consider adding into their regular diets, include: fatty fish, such as salmon or tuna; some sea foods, such as oysters; and mushrooms and egg yolks.