In October 2008, the National Cancer Institute halted a study designed to test whether vitamin E and selenium, taken alone or in combination, could prevent prostate cancer after data showed the supplements might be doing more harm than good. The news didn’t get any better at the annual meeting of the American Urological Association in April 2009.
Canadian researchers hypothesized that vitamin E and selenium, taken with soy protein, might prevent the development of prostate cancer in men who had already been diagnosed with high-grade prostatic intraepithelial neoplasia (HGPIN), a condition thought to be a cancer precursor. They tested their theory in 303 men, with half taking the supplements and the other half taking a placebo daily for three years. The men had prostate biopsies after six, 12, 24, and 36 months to see if they developed prostate cancer.
Over all, 26.4% of the study’s participants developed invasive prostate cancer, with no meaningful difference in the number of cancer cases between the two groups. The findings highlight the importance of conducting randomized trials of dietary supplements, many of which are falsely promoted as cancer fighters.
SOURCE: Fleshner NE, Kapusta L, Hersey K, et al. Randomized Trial of Combination Vitamin E, Selenium, and Soy Protein Among Men with High Grade Prostatic Intraepithelial Neoplasia (HGPIN). Journal of Urology 2009;181(4 Suppl): abstract 736.
Originally published September 2009; last reviewed February 24, 2011.