[Roles of folate metabolism in prostate cancer]

Epidemiological surveys show that folic acid can prevent prostate cancer, but fortified folic acid may increase the risk of the malignancy. The physician data queries from the National Cancer Institute of the USA describe folate as protective against prostate cancer, whereas its synthetic analog, folic acid, is considered to increase prostate cancer risk when taken at levels easily achievable by eating fortified food or taking over-the-counter supplements. We review the current literature to examine the effects of folate and folic acid on prostate cancer, help interpret previous epidemiologic data, and provide a clarification regarding the apparently opposing roles of folate for patients with prostate cancer. A literature search was conducted in Medline to identify studies investigating the effect of nutrition and specifically folate and folic acid on prostate carcinogenesis and progression. In addition, the National Health and Nutrition Examination Survey database was analyzed for the trends in serum folate levels before and after mandatory fortification. Folate likely plays a dual role in prostate carcinogenesis. There remains some conflicting epidemiologic evidence regarding folate and prostate cancer risk. However, there is growing experimental evidence that higher circulating folate levels can contribute to prostate cancer progression. Further research is needed to clarify these complex relationships.