Researchers found Folic acid supplements often taken by breast cancer patients and survivors could actually be promoting tumor growth.
A research team found these supplements increased the growth of existing breast cancer in rats, a St. Michaels Hospital news release reported.
The B vitamin folate (folic acid when in its synthetic form) has caused controversy in the medical community over whether or not folic acid promotes breast cancer growth.
This study is the first to show that taking doses of folic acid 2.5 to five times higher than the daily requirement "significantly promotes" the growth of existing precancerous and cancerous cells in the mammary glands of rodents.
"This is a critically important issue because breast cancer patients and survivors in North America are exposed to high levels of folic acid through folic acid fortification in food and widespread use of vitamin supplements after a cancer diagnosis," Doctor Young-In Kim a physician and researcher at St. Michael's Hospital, said in the news release. "Cancer patients and survivors in North America have a high prevalence of multivitamin and supplement use, with breast cancer patients and survivors having the highest prevalence."
Over the past 15 years folic acid consumption has drastically increased in the U.S, although pregnant women are encouraged to take the supplements to prevent birth defects such as spina bifida. Between 30 and 40 percent of North Americans take folic acid supplements despite the fact that its health benefits have never been proven.
Since the late 1990s U.S. and Canadian governments have required food manufacturers to enrich flour, cornmeal, and pasta with folic acid to help women consume enough vitamin B.
Researchers suggest the supplements could be useful in conditions such as "cognitive enhancement, [other types of] cancer, psychiatric illnesses, and cardiovascular conditions," MayoClinic reported. It can also relieve symptoms associated with low blood folate levels.
