Folate is a B vitamin required by the body for multiple normal functions. Along with other B vitamins such as B6 and B12, folate is important in sustaining our DNA. Eating a healthy diet that includes the right amount of folate may be an important factor in lowering risk of breast cancer, particularly in young women.

The largest folate study to date–the EPIC study–was published in the January 2015 issue of the Journal of the National Cancer Institute by de Batlle and colleagues. More than 350,000 women in ten European countries participated in the study examining their diet, lifestyle, and medical history. These women were followed for 11 years to determine patterns in breast cancer development. In younger women who were still menstruating, the risk of breast cancer was lower with more folate intake. The finding in this study is significant given that breast cancer in younger women is often more aggressive than in older women. The risk was even lower when tumors without estrogen or progesterone receptors (ER- or PR-) were considered. Risk of cancer that is estrogen receptive (ER+) is strongly driven by estrogen exposure over time. However, other studies have suggested the risk of ER- cancers may be more sensitive to dietary components, such as B vitamins.

Folate is already recognized as an important component of a healthy diet and can be found in foods such as green vegetables like broccoli, green beans, peas, dark leafy lettuce, and spinach. Folate is also found in many fruits, vegetables, and seeds. Previous studies of folate and breast cancer risk have yielded mixed results with no clear consensus. However, other health benefits of folate are well known, such as protection from cardiovascular disease, lower risk of colon cancer, and improved health of pregnant women and their unborn infant. Prenatal vitamins are designed to supplement the diet with 400 micrograms of folate to protect mother and baby. The amount of folate in the diet needed to impact breast cancer risk remains unclear. Interestingly in the EPIC study, breast cancer risk was lower with increasing folate intake, and lowest in women taking 400 micrograms daily.

Another important risk factor for developing breast cancer is drinking alcohol. Women with more than moderate drinking habits increase their chances of breast cancer diagnosis. Alcohol prevents the body’s ability to use folate. Previous studies indicate that in women who drink alcohol, increased folate levels may “cancel out” some of the increased breast cancer risk. In the EPIC study, women who consume two drinks per day had significantly lower chance of breast cancer if they had high folate levels. Further study will be needed to confirm these results, but avoiding heavy drinking and eating a healthy diet rich in folate may help lower a woman’s risk of developing breast cancer.

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Hank Schmidt, MD, PhD FACS, is and Assistant Professor in the Department of Surgery at Icahn School of Medicine at Mount Sinai and Director of the Cancer Risk Program at Dubin Breast Center of the Tisch Cancer Institute.