According to a study in the June 6 issue of JAMA, folic acid supplements do not appear to reduce risk of colorectal tumors. Some previous studies have suggested that folate supplementation may help to prevent colorectal tumors.
Bernard F. Cole, Ph.D., of Dartmouth Medical School, Hanover, N.H., and colleagues evaluated the effect of folate for the prevention of new colorectal adenomas in persons with a history of these types of lesions. The trial was conducted at 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.
Participants were randomly assigned to receive 1 mg/day of folic acid (n = 516) or placebo (n = 505), and were separately randomized to receive aspirin (81 or 325 mg/day) or placebo. Follow-up consisted of two colonoscopic examination cycles (the first interval was at 3 years and the second at 3 or 5 years later).
Contrary to what the researchers expected, more adenomas were seen in people who received folic acid. In the first follow-up interval, adenomas occurred in 42.4 percent of the participants in the placebo group and 44.1 percent of the participants in the folic acid group. In the second follow-up interval, adenomas occurred in 37.2 percent of the participants in the placebo group and 41.9 percent of the participants in the folic acid group.
In both follow-up intervals, participants in the folic acid group tended to have higher rates of advanced adenomas and multiple adenomas. Advanced adenomas have features, such as larger size, that increase the risk that they will develop into colorectal cancer. In the first follow-up interval, advanced adenomas occurred in 8.6 percent of the participants in the placebo group and 11.4 percent of the participants in the folic acid group.
The respective numbers in the second follow-up intervaPage: 1 2 Related medicine news :1
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