CRN criticizes vitamin E dosage report
come in for criticism from the Council for Responsible Nutrition,
which says it was based on a flawed study, reports Jess
Halliday.
The report, which NutraIngredients-USA.com covered on Tuesday, claimed that 11.3 percent of survey respondents consume more than 400 IU a day from vitamins, minerals or other dietary supplements.
"If people who consume 400IU or greater of vitamin E per day are indeed at increased risk for premature death, a sizeable percentage of US adults fall into this risk group," wrote the authors, led by Earl Ford of the Centers for Disease Control and Prevention.
They took their premise from the conclusions drawn by Edgar Miller, associate professor of medicine at Johns Hopkins University in Baltimore, in his meta-analysis of vitamin E published in AIM last October.
But the CRN disputed the validity of Miller's analysis and, by extension, find fault with the Ford report.
"The authors start their review with a predetermined conclusion," VP scientific and regulatory affairs Dr Andrew Shao told NutraIngredients-USA.com. "They take the approach that the analysis is fact, but it has many flaws and various biostatisticians have gone on the record saying so."
He said that, in the absence of the Miller study, there would be no basis whatsoever for the latest communication.
The original meta-analysis sought to establish whether there is a dose-dependant response to vitamin E by studying death rates in 14 published clinical trials comparing vitamin E supplementation to placebo, undertaken between 1993 and 2004.
Miller and his team concluded that daily vitamin E doses of 400IU or more can increase the risk of death and should be avoided.
But the CRN took exception to this conclusion, saying that it "inappropriately tries to draw conclusions for the whole population based on a combination of studies of people who were already at grave risk with existing diseases including cancer, heart disease, Alzheimer's, Parkinson's and kidney failure".
The trade body said that even though the researchers noted limitations in their meta-analysis, they continue to "make sweeping generalizations about the use of vitamin E and all-cause mortality for the whole population, although they provide no evidence that these kinds of effects would occur in healthy populations".
Dr Donald Berry of the University of Texas Anderson Cancer Center agrees. "I think that study is flawed," he told NutraIngredients-USA.com. "It is based on a most inappropriate model and is an inappropriate and rather naive analysis. Any reasonable model comes to a different conclusion."
Ford wrote that the findings of a Women's Health Study published in the New England Journal of Medicine produced results consistent with Miller's meta-analysis, but Shao pointed out that these were two very different types of research (the women's study being an intervention trial), so they cannot be directly compared.
Moreover, another Women's Health Study published in the July issue of the Journal of the American Medical Association, actually contradicted Miller's conclusions, finding that vitamin E could lower the risk of heart attacks and stroke in older women as well as cardiovascular deaths, although it is unlikely to prevent heart disease or cancer.
Shao also pointed out that the data for Ford's report was taken from the National Health and Nutrition Examination Survey, which was conducted primarily amongst healthy individuals.
"They combine this with a flawed meta-analysis on diseased individuals, then make an extrapolation to the population as a whole," he said.
