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Eric Klein, MD and his associates wanted to study the effects of selenium and Vitamin E on prostate cancer. They created the “Selenium and Vitamin E Cancer Prevention Trial” or SELECT trial, to see how these agents affected the occurrence of prostate cancer. 34,887 men were placed in 4 groups; 1 each with selenium or vitamin E, 1 with both, and 1 with neither. This is an important study because they randomized a large number of people and achieved excellent statistical power for the study with minimal bias. The study participants had no clinical evidence of prostate cancer at enrollment based on PSA and digital rectal exam (DRE). A 7 year minimum time of follow-up was proscribed with a 12 year maximum. The men were at least 50 years old if African-American, or 55 for other men.
The initial report in 2008 showed no reduction in the risk of prostate cancer with either selenium or Vitamin E, but a recent update with longer-term followup has generated new findings. It seems that in the vitamin E group 620 men developed prostate caner, compared to 575 taking selenium alone or 529 when taking neither. These results are too different to be random results, and the conclusion of the study is that supplementation of 400 IU of vitamin E a day carries a higher risk for the development of prostate cancer. The grade of the cancer did not seem to be affected. The daily recommended dose of vitamin E is only 22.4 IU, so it is hard to get 400 IU in a normal diet.
This is only one study, albeit a good and well-designed one. There will certainly be more information on this in the coming years.