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Folate, Folic Acid May Raise Breast Cancer Risk in Some Women


Women have been urged to ensure they get enough folate or folic acid to prevent birth defects, and also because it reduces the risk of breast cancer. But a new study from Lund University shows that in some women, such advice needs a second look, because folate increases the risk of breast cancer instead.

The recommended intake of folic acid—the synthetic form of the B vitamin added to food—or folate, which is the form found naturally in leafy green vegetables and other foods, is 400 micrograms daily, prior to conception and during early pregnancy. This step has been shown to reduce the risk by up to 70 percent of an infant being born with a serious neural tube defect, such as spina bifida.

In some women, however, their genetic makeup is such that folate increases their risk of developing breast cancer. At Lund University, Ulrika Ericson evaluated the data from the Malmo Diet and Cancer study, which had information and blood samples from more than 17,000 women from the 1990s.

Slightly more than 500 women in the study had developed breast cancer by the end of 2004. When the food habits, folate levels, and genetic make-up of the women in these breast cancer patients were analyzed and compared with those of healthy women in the study, some interesting findings emerged. Women who had consumed the amount of folate recommended in Sweden had 50 percent the risk of developing breast cancer as women who had consumed the lowest amount of folate, indicating that folate protects against breast cancer.

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An unexpected finding was that in some women, the risk of breast cancer increased as their intake of folate increased. These women had inherited a specific variation of an enzyme that dictates how the body uses folate. The greatest risk of breast cancer was found among the ten percent of women who had inherited the enzyme variation from both of their parents. Taking folic acid in supplements added to the increased risk.

Given these findings, Ericson does not believe women should take supplements that contain folic acid unless they have a special reason to do so. She identified two groups of women who would have a special reason: those who have low folate levels and a certain type of anemia, and women who are trying to become pregnant.

She suggests that all other women not take vitamin supplements that contain folic acid until more is known about the link between folate and different types of cancer. For now, women do not know which genetic variant of the enzyme they have. “It is better to eat a diet containing a lot of fruit, vegetables, legumes and wholemeal products,” Ericson says. Such a diet provides a sufficient amount of folate and other nutrients.

In 1992, the US Public Health Service (USPHS) recommended that all women capable of becoming pregnant consume 400 micrograms of folic acid daily. This recommendation was followed by mandatory fortification of cereal grain products with folic acid, which went into effect in January 1998.

In Sweden, the site of the current study, and in many other countries, no such mandate exists. Ericson notes that there needs to be a better understanding of the link between folate and different types of cancer, including breast cancer, before such a move is considered. Otherwise, some women may be placed at increased risk of breast cancer.

Lund University
US Public Health Service