CORVALLIS, Ore. Generations of studies on vitamin E may be largely meaningless, scientists say, because new research has demonstrated that the levels of this micronutrient necessary to reduce oxidative stress are far higher than those that have been commonly used in clinical trials.
In a new study and commentary in Free Radical Biology and Medicine, researchers concluded that the levels of vitamin E necessary to reduce oxidative stress as measured by accepted biomarkers of lipid peroxidation are about 1,600 to 3,200 I.U. daily, or four to eight times higher than those used in almost all past clinical trials.
This could help explain the inconsistent results of many vitamin E trials for its value in preventing or treating cardiovascular disease, said Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University, and co-author of the new commentary along with Jeffrey Blumberg, at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.
The methodology used in almost all past clinical trials of vitamin E has been fatally flawed, said Frei, one of the worlds leading experts on antioxidants and disease. These trials supposedly addressed the hypothesis that reducing oxidative stress could reduce cardiovascular disease. But oxidative stress was never measured in these trials, and therefore we dont know whether it was actually reduced or not. The hypothesis was never really tested.
The level of vitamin E that clearly can be shown to reduce oxidative stress, new research is showing, is far higher than the level that could be obtained in any diet, and is also above the tolerable upper intake level outlined by the Institute of Medicine, which is 1,000 I.U. a day. OSU researchers are not yet recommending that people should routinely take such high levels, but they do say that controlled clinical trials studying this issue should be aware of the latest findings and seriously consi
|Contact: Balz Frei|
Oregon State University