Supplementation with folic acid significantly increases the risk of prostate cancer, according to the results of a study recently published in the Journal of the National Cancer Institute.[1]

The role of micronutrients in relationship to cancer incidence has become a major focus among researchers. Some dietary choices have been shown to reduce the risk of developing certain types of cancers; however, newer research has also shown an increase in incidence associated with some nutrients. The nutritional prevention of cancer is a complex issue. Dietary intake of certain nutrients often produces different results from supplementation. Research is ongoing in this area.

The Aspirin/Folate Polyp Prevention Study was a placebo-controlled, randomized trial of aspirin and folic acid supplementation for the prevention of colorectal adenomas. The study included 643 men who were randomly assigned to placebo or supplementation with folic acid. The men completed food frequency questionnaires (FFQ) and also provided nonfasting blood samples for the measurement of circulating levels of folate and other B vitamins. The men were followed for a median of seven years.

The results indicated that the estimated probability of being diagnosed with prostate cancer was 9.7% for the men in the folic acid group compared with 3.3% in the placebo group. Interestingly, the baseline dietary folate intake and the level of circulating folate in the blood among the placebo group were associated with a decreased incidence in prostate cancer.

The researchers concluded that daily supplementation with 1 mg of folic acid was associated with an increased risk of prostate cancer; however, they acknowledged that supplementation may have different effects from dietary intake.

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