There has been a great deal of interest in recent years regarding the use of vitamin supplements as a means of preventing many types of cancers -- including prostate cancer. One vitamin supplement that has gained a particularly high level of attention is folic acid.
So, is there any link between taking folic acid supplements and prostate cancer?
One study from 2009 showed that, amongst more than 600 men who had taken folic acid supplements as part of a study to determine if aspirin or folic acid intake could reduce the number of colon polyps, there was a significantly higher rate of prostate cancer in those men who had taken the folic acid supplements versus those who had not. The men were instructed to take more than two times the normal daily requirement for folic acid. Other men were give a placebo (a pill that looked identical to the folic acid pill, but without any actual nutritional or active component).
In fact, in this study (which was published in the Journal of the National Cancer Institute), the rate of prostate cancer over the course of 10 years in men who took the folic acid supplements was 9.7% while it was only 3.3% in men not taking the supplements.
The study found no significant increase in the rates of prostate cancer for men who were taking aspirin supplements.
While this study was not done with the intention of determining the effect of folic acid supplementation on prostate cancer risk and it was also too small of a study to truly show a cause-effect relationship, it does give a fairly clear signal that the folic acid supplements do not provide a protective benefit against prostate cancer.
Previous studies have shown that folic acid supplements also do not provide measurable protection against colon cancer (or against developing colon polyps).
Folic acid is only one of many vitamin supplements that have not been shown to benefit patients seeking to lessen their risk of prostate cancer. Other studies have shown that two very promising vitamin (or mineral) candidates -- vitamin E and selenium -- afford no benefits for lowering the risk of prostate cancer.
Figueiredo JC, Grau MV, Haile RW, et al. Folic acid and risk of prostate cancer: results from a randomized clinical trial. J.Natl.Cancer Inst.101(6):432–5.
Jacobs EJ, Rodriguez C, Mondul AM, et al. A large cohort study of aspirin and other nonsteroidal anti-inflammatory drugs and prostate cancer incidence. J.Natl.Cancer Inst.97(13):975–80.
Lippman SM, et al. Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51