According to a study published in this week’s Journal of the American Medical Association (JAMA), taking folic acid, vitamin B6 or vitamin B12 supplements does not reduce (or increase) the risk of invasive cancer or breast cancer in women. This study was conducted because previous studies had suggested a protective effect for B vitamins against cancer.

In the JAMA study, the researchers examined the incidence of invasive cancer and breast cancer among 5,442 female health professionals who took daily supplements of folic acid and vitamins B6 and B12 and those who took a placebo. There was no real difference in cancer rates between the groups of women studied. Women in this study had preexisting heart disease or several risk factors for heart disease.  

B vitamins are important for growth and other cellular functions. Leafy green vegetables and fortified cereals are a good source of folic acid and other B vitamins. Folic acid is added to cereals and breads to prevent serious birth defects.  The March of Dimes recommends that women take a daily multivitamin with 400 micrograms of folic acid before and during early pregnancy to prevent neural tube defects in babies.

At least for now, there appears to be little benefit for women who take folic acid or other B vitamin supplements in order to prevent cancer.  

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