Folic acid does not prevent colorectal cancer

Despite the fact that some previous studies have suggested that folate supplementation may help to prevent colorectal cancer, a new study says that is not the case and it may in fact increase the risk for some types of colorectal tumors.

The study which was based on data from 987 adults with a history of precancerous colon polyps, over a ten year period, those who took folic acid developed more growths, or adenomas, several years later than the people who took a placebo.

The researchers say they did not see any real difference in rates of colon cancer, only in the precancerous colon growths.

The study data involved reports from nine clinical centers in the U.S. and Canada between July 1994 and October 2004 and included 1,021 men and women with a recent history of colorectal adenomas but no previous large intestine cancerous tumor.

The participants were randomly assigned to receive folic acid or a placebo, and were separately randomized again to receive aspirin or a placebo.

Two colonoscopic examinations were done at 3 years and 3 or 5 years later and the researchers were surprised to find more adenomas in people who received folic acid.

The researchers concluded that high doses of folic acid taken for up to 6 years, does not decrease the risk of adenoma formation in the large intestine in those with previously removed adenomas and may actually increase the risk of developing the growths.

Scientists are saying that the folic acid fortification, now required in some U.S. foods, should not be increased and that other nations considering fortification should be cautious.

Folic acid is an artificial version of folate, a B vitamin found in leafy vegetables, citrus fruit and beans; it prevents birth defects and is needed for the production of red blood cells.

The study was funded by grants from the National Institutes of Health.

The research appears in the Journal of the American Medical Association.