The review, published in the April issue of the American Journal of Clinical Nutrition, offers reassurance to those concerned about safety since the media storm surrounding last November's publication of a meta analysis, stating that daily vitamin E doses of 400 IU or more can increase the risk of death and should be avoided.
Led by John Hathcock, VP for scientific and international affairs at the Council for Responsible Nutrition (CRN), the latest investigations took into account 95 clinical trials and epidemiological studies in humans, including the controversial meta-analysis on vitamin E at Johns Hopkins University.
"This peer-reviewed expert analysis should help reassure consumers about the safety of vitamin E for a healthy population at the most common daily doses on the market-400 IU and 200 IU-for vitamin E single supplements," said Hathcock.
He added that they should not view this conclusion as carte blanche to exceed recommended doses on product labels, however, pointing out that the tolerable upper intake level (UL) is a dose at which "there is no known harm but it is not a recommendation or suggestion for daily use."
Vitamins E and C are well known antioxidants which are thought to help protect against Alzheimer's, age-related macular degeneration, cataracts, some cancers and ischemic heart disease.
But these perceived benefits lead some people to consume them in quantities that greatly exceed the recommended daily dose.
"Numerous studies of vitamin C supplementation have provided no pattern of evidence to support concerns about safety other than occasional gastrointestinal upset or mild diarrhea resulting from the osmotic effects of unabsorbed quantities of vitamin C," said the authors.
They also said that evidence of potential adverse effects of high vitamin E intakes in humans, including bleeding, is "not convincing".
These latest conclusions on vitamin E differ significantly from those drawn by the Institute of Medicine (IOM), which extrapolated its UL of 1000mg (equivalent to 1000 IU synthetic or 1500 IU natural) from animal data in some 340 peer-reviewed scientific studies.
The CRN responded to the negative publicity about vitamin E in November by launching an advertising campaign featuring quotes from several health researchers refuting the negative claims, noting the presumed benefits of vitamin E, and drawing attention to the IOM findings.
However some ingredients companies have felt the impact of falling sales. DSM Nutritional Products said it saw a drop in sales the week after the John Hopkins study was reported by the media.
Last week global supplement maker NBTY blamed its considerable decrease in net income in 2Q 2005 on poor sales of vitamin E products, coupled with the low carb lifestyle falling out of favor.