Reports from clinical trials involving vitamin E supplementation have been mixed. Many of these studies focused on heart disease, with some showing benefits, while others did not. Some trials have reported adverse health outcomes associated with vitamin E supplements. Perhaps most concerning were the results of SELECT clinical trial – a cancer prevention study that found high-dose (400 IU/day) vitamin E supplementation increased the risk of prostate cancer in healthy men.
Often these clinical trials, as with the SELECT trial, provided vitamin E in dosages far exceeding dietary intake recommendations (15 mg/day or 22.5 IU/day of α-tocopherol). Thus, based on the totality of the evidence to date, the Linus Pauling Institute no longer recommends high-dose vitamin E supplements. However, this should not be interpreted to mean that vitamin E itself is something to be avoided.