Folic Acid Fortification: Good for Pregnancy, Not So Much Later in Life

There's no question that the addition of folic acid to most breads, pasta and rice has led to a noticeable decrease in the rate of neural tube impairments, such as spina bifida and anencephaly, in newborns. In fact, according to the Boston Globe, fortifying foods with this essential B vitamin has saved more than 1,000 babies born in the U.S. and Canada each year from these debilitating and sometimes deadly impairments.

But all this fortification could be too much of a good thing, according to data from researchers at Tufts University, who found that the rate of decrease corresponds to a noticeable increase in the rate of cases of colorectal cancer. Lawrence Lindner of the Globe writes:

The study, published in Cancer Epidemiology Biomarkers & Prevention, shows that before the late 1990s, the incidence of colon cancer was decreasing on a steady, predictable curve, presumably because of increased screening with colonoscopies, during which precancerous polyps and early cancers are removed. However, the curve has shifted.

Colon cancer cases continue to decline, but since the advent of folic acid fortification, there have been four to six more cases of colon cancer per 100,000 people in the United States and Canada each year than the original curve would have projected -- translating to an estimated extra 15,000 people diagnosed per year in this country and another 1,500 in Canada.

Nothing's been proven for sure, but the theory is that while folic acid can help protect noncancerous cells from becoming cancerous, "an estimated 35 percent to 50 percent of people over 50 already have precancerous polyps -- and for them, the extra folic acid may be dangerous," writes Lindner. "The precancerous cells replicate more rapidly than normal ones, and folic acid seems to put that process into overdrive."

Joel Mason, the leader of the study and director of the Vitamins and Carcinogenesis Laboratory at the USDA Human Nutrition Research Center at Tufts, said this doesn't mean folic acid fortification should cease.

"It is highly unlikely that women in their 20s and 30s, childbearing age, harbor any precancerous or cancerous cells, and there is incontrovertible evidence now that supplemental quantities of folic acid are going to help prevent really devastating birth defects," Mason said.

Rather, once people reach middle age, they should be cautious about taking supplemental folic acid in multivitamins.

"The single biggest risk factor for colon cancer is older age," adds Mason.