Fooled by Folic Acid?

Folic acid supplement shown to increase risk of breast cancer in female rats

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) According to a new study working with rat animal models, female offspring of rats who took folic acid supplements before conception, during pregnancy and while breast-feeding have twice the rate of breast cancer.

These female rats also exhibited more tumors that developed at a faster rate than the others, according to research from St. Michael's Hospital in Tornoto, led by Dr. Young-in Kim, a gastroenterologist.

For the study, half of a group of rats were given the equivalent of folic acid a pregnant woman would take three weeks before mating and throughout the pregnancy and lactation. After weaning, half of the female offspring were given the same amount of folic acid supplement as the pregnant rats. The rats whose mothers took folic acid supplements and were subsequently fed a supplemented folic acid diet had a twofold increase in the rates of mammary tumours than the control groups.

Dr. Kim cautioned more studies in humans would be need to happen before pregnant women begin to panic based on the study's findings, especially since rats and humans metabolize folic acid differently.

Folic acid, a B vitamin, is routinely advised for pregnant women to prevent against birth defects such as spina bifida.

While natural folate -- found in green, leafy vegetables -- may prevent certain cancers, it may also play a role in increased risk of other cancers, according to the study led by Dr. Kim.

Dr. Kim concluded that folic acid may decrease some cancers while promoting others.

Severe folic acid supplement side effects may include rash, hives, itching, difficulty breathing, tightness in the chest, and swelling of the mouth, face, lips or tongue. There are no reported common side effects to taking folic acid supplements.

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Review Date: 
February 14, 2011
Last Updated:
February 15, 2011