Data are now available from more than 35,000 men aged 50 and older who participated in the NCI-funded Selenium and Vitamin E Cancer Prevention Trial (SELECT), indicating that selenium and vitamin E supplements did not prevent prostate cancer, when taken either alone or together. The data also show small, statistically insignificant increases in prostate cancer cases among men who took only vitamin E and also in adult-onset diabetes cases among men taking only selenium.

Another trial, the Physicians' Health Study II, followed more than 14,600 male physicians aged 50 years and older who took vitamin E, vitamin C, a combination of both, or placebos over a 10-year period. The rates of prostate, colorectal, lung, and other cancers were similar among all study groups.

Results from both trials were published online December 9 in the Journal of the American Medical Association. "Physicians should not recommend selenium or vitamin E - or any other antioxidant supplements - to their patients for preventing prostate cancer," wrote Dr. Peter Gann of the University of Illinois at Chicago in an accompanying editorial.