Folic acid may boost prostate cancer risk: study

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(Xinhua)
Updated: 2009-03-11 14:23

LOS ANGELES -- Folic acid, taken in high doses, is likely to increase the risk of prostate cancer, according to a University of Southern California study published on Tuesday.

Men who took a daily folic acid supplement of one milligram daily had more than twice the risk of prostate cancer compared with men who took a placebo, lead author Jane Figueiredo reported in the online edition of the Journal of the National Cancer Institute.

Previous studies showed that folic acid, or folate, a B vitamin found in vegetables, beans, fruits and whole grains, can be used to reduce neural tube defects in infants while taken by the mother before or during pregnancy.

"We know that adequate folate levels are important in the prevention of several cancer types, cardiovascular and neurological diseases," said Figueiredo. "However, little has been known about its role in prostate cancer."

The researchers analyzed the results of a trial of 643 men who were randomly assigned to one milligram daily folic acid supplements or placebo.

The estimated prostate cancer risk through 10 years was 9.7 percent for men who took folic acid supplements, compared with 3.3 percent for men who took placebo, said the researchers.

Consumption of folic acid naturally through foods, however, didn't produce the same prostate cancer risk, the researchers said.

"The synthetic form of folate, folic acid, found in supplements, is more bioavailable compared to folate from dietary sources and we know the amount of folate available is critical," Figueiredo explained. "Adequate levels of folate may be beneficial, but too much folate is unlikely to be beneficial."

Alternatively, these results may be due to chance, and replication by other studies is needed, she noted.