In rats, folic acid supplements in doses 2.5 to five times the daily requirement significantly promotes the growth of existing pre-cancerous or cancerous cells in the mammary glands, says study published in PLOS ONE.
"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," Dr. Kim said. "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." The amount of folic acid consumed in North America has increased dramatically in the past 15 years.
Breast Cancer: Breast cancer is the most common cancer among women worldwide. Early detection and life style changes help in controlling breast cancer. Breast cancer incidence increases with age; the older the woman, the more aggressive the evaluation techniques employed. Nevertheless, younger women with breast lumps are at a far greater risk for breast cancer in comparison to asymptomatic women of the same age group, and to older women. Breast cancer mostly occurs in women over the age of 50, and the risk is especially high for women over age 60.
Women are routinely advised to take folic acid supplements before becoming pregnant and while pregnant to prevent neural tube birth defects such as spina bifida. Since 1998, the Canadian and U.S. governments have required food manufacturers to add folic acid to white flour, enriched pasta and cornmeal products as a way of ensuring women receive enough of the B vitamin. In addition, up to 30 to 40 per cent of North Americans take folic acid supplements for possible but as yet unproven health benefits. Dr. Kim is also a professor of medicine at the University of Toronto.This research was funded in part by the Canadian Institutes of Health Research.