Two large trials revealed that selenium, vitamin E and C didn’t reduce the risk of developing prostate cancer.

In one of the trials, carried out by Dr. J. Michael Graziano of Brigham and Women’s Hospital, over 14,000 male doctors age 50 or more were assigned to take vitamin C, vitamin E, both of them or placebos. The health of each participant was followed over a period of eight years on average. During the clinical trial, almost 2,000 men developed prostate cancer. However, researchers found that the intake of the supplements didn’t have an impact on participants’ likelihood of developing the disease, or any other malignancy.

The other trial, conducted by the University of Texas M.D. Anderson Cancer Center, involved more than 35,000 men age 50 or older, who were also randomly assigned to selenium, vitamin E or dummy pills groups. Data showed that, after 5 years on average, more than 1,700 cases of cancer emerged. Researchers halted the study due to the disastrous results showing that the vitamin and the antioxidant, taken alone or together, failed to cut the risk of prostate or other cancers in the male participants.

According to Dr. Peter H. Gann of the University of Illinois at Chicago, "it may be time to give up the idea that the protective influence of diet on prostate cancer risk […] can be emulated by isolated dietary molecules given alone or in combination to middle-aged and older men."

A recent similar study found a little more cases of prostate cancer in the participants who only took vitamin E and, in addition to this, a little more cases of diabetes in those who only took selenium.