New findings call into question the ability of vitamin E to reduce oxidative stress.
A new study in Free Radical Biology and Medicine has found that the levels of vitamin E necessary to reduce oxidative stress are four to eight times higher than those used in almost all previous clinical trials.
Co-author Dr Balz Frei said this meant all past research had been "fatally flawed".
He continued: "A pill count simply isn't enough to determine the value of vitamin E. We need to select people for trials properly, make sure they are taking the right form of the vitamin, at the right levels and at the right time, and then verify the metabolic results with laboratory testing."
"Only when we do these studies right will we answer questions about the value of vitamin E in addressing cardiovascular disease. So far we've been flying blind."
According to the findings, the amount of vitamin D needed to reduce oxidative stress is 600 to 3,200 IU daily; typically, supplements contain 100 to 400 IU.