Folic Acid Increases The Risk Of Prostate Cancer

By Margarita Nahapetyan

A new 10-year study by scientists at the University of Southern California (USC), revealed that men who have been taking 1 mg of folic acid supplements on a daily basis, increased their chance of developing prostate cancer.

However, the incidence of prostate cancer in the study was slightly lower in men who simply got adequate amounts of folic acid from their dietary intake. The research based its findings on a secondary analysis of the Aspirin/Folate Polyp Prevention Study (AFPP), a placebo-controlled randomized trial that was carried out to determine the effect of aspirin and folic acid on colon polyps in men and women who were at high risk for the disease. The study, conducted between 1994 and 2006, showed that while aspirin reduced the risk of colon polyps, folic acid actually increased the incidence of advanced and multiple polyps.

Folic acid (synthetic version of folate) is a B vitamin that is present in many green, leafy vegetables, beans, fruits, peas, nuts as well as in fortified cereals and whole grains. There is a proven evidence that folic acid reduces neural tube defects, like spina bifida, in infants while taken by women before or during pregnancy. According to a number of scientists, circulating levels of folate are crucial for preventing many diseases, including cancer, heart disease and neurological diseases, but they warn that too much circulating folate may be harmful.

In the current investigation, the scientists looked at the impact of folic acid supplements on prostate cancer risk. They recruited 643 men, and tracked them for slightly more than ten years. All men have been randomly assigned to placebo group or supplement group with daily low-dose aspirin and 1 mg of folic acid on a daily basis - more than twice the recommended daily amount of the most multivitamins for men and for women who are not pregnant or nursing.

According to the results, the estimated prostate cancer risk after ten years, was 9.7 per cent for the men who took the daily 1-mg supplements of folic acid, compared to 3.3 per cent risk for those who took a placebo. Aspirin alone was found to have no significant effect on prostate cancer risk, but taking folic acid was found to increase the risk for prostate cancer by 163 per cent. It was also found that the men who had high levels of folate in their blood and who consumed diet rich in folate, appeared to have a reduced risk of prostate cancer. But the researchers said that the difference was not statistically significant. It remains unclear why dietary and circulating folate among non-multivitamin users may be inversely associated with risk, said a lead author of the study, Jane Figueiredo, an assistant professor of preventive medicine at the University of Southern California.

The analysis joins a growing number of studies suggesting that nutritional supplements are of no benefit for preventing cancer. The experts wonder if the results of the current study are strictly due to chance, and say that much more investigation and research about the risk of prostate cancer from folic acid supplements are needed in order to make any certain and definite conclusions.

The report appears online, in March issue of the Journal of the National Cancer Institute. The study was funded by the U.S. National Cancer Institute and the U.S. National Institutes of Health.