Extra Vitamin E Found Safe Yet Ineffective; Debate Goes On


The good news from a new pooled analysis of 57 studies is that, despite some red flags from previous research, vitamin E supplements are safe and dont increase the risk of death. But neither do the once-highly touted supplements help you live longer, the review reports, despite hopes their antioxidant effects might fight chronic disease. Calling their meta-analysis the largest and most inclusive to date, scientists concluded in Current Aging Science that vitamin E supplementation cannot be endorsed as a means of reducing mortality.

Erin L. Abner, MPH, of the University of Kentucky, and colleagues combined results from clinical trials between 1988 and 2009 totaling more than 24,000 participants, lasting an average of 2.6 years. Prior findings on vitamin E supplementation of more than 400 IU daily had been contradictory, with some studies reporting a slight but significant increase in mortality. But the new review concluded, Supplementation with vitamin E appears to have no effect on all-cause mortality at doses up to 5,500 IU per day.

Neither, however, did Abner and colleagues find a positive effect from vitamin E supplements. In theory, they noted, antioxidants such as vitamin E should benefit conditions associated with oxidative stress. But their review of randomized clinical trials found that vitamin E supplementation for prevention or treatment of disease has not been supported by the accumulated evidence.

Dont think for a minute, however, that this meta-analysis represents the last word on vitamin E supplements. Jeffrey B. Blumberg, PhD, director of Tufts HNRCA Antioxidants Research Laboratory, says, I guarantee you there will be more such meta-analyses, all of them limited by the factors these authors list at the end of their report plus more they do not discuss.

Abner and colleagues noted that such analyses are fraught with potential sources of statistical bias, as well as the challenges of combining different study populations. How strictly participants adhere to a supplementation regimen is another potential issue. And, although some included trials lasted up to 10 years, the average of just 2.6 years may not be long enough for vitamin Es benefits to prove significant.

Moreover, as the researchers also conceded, such trials often dont focus on vitamin E in isolation. Blumberg explains, The analysis includes many trials that tested vitamin E in combination with one or more other nutrients as well as drugs, and in patients at high risk of dying from their disease. It nonetheless attributes the effect on all-cause mortality-in this case a null outcome-to be due only to vitamin E.

Blumberg and colleagues published their own meta-analysis last year in the journal Nutrients, after the scare in which vitamin E was thought to actually increase mortality. Of 66 trials of antioxidant supplements including vitamin E, they found 39 had a null outcome (neither positive nor negative), 24 had a positive outcome and only 3 showed negative results.

In any case, Blumberg says, the latest meta-analysis notion that vitamin E might benefit mortality is flawed. To the extent that many studies hypothesized vitamin E supplements might reduce the risk of one or another chronic disease, none ever suggested that it would reduce total mortality. Indeed, has anyone ever suggested that a single nutrient can reduce ones death from all known causes-including accidental deaths and homicide? Nutrients are not miracles.

He points out that many studies, including trials funded by the US Department of Agriculture and the National Institutes of Health, continue to probe possible health benefits of extra vitamin E, alone or in combination. While the vitamin E debate goes on, however, keep in mind that the major source of vitamin E continues to be food.

TO LEARN MORE: Current Aging Science, 2011, 4. Nutrients, August 30, 2010; online at dx.doi.org/10.3390/nu2090929.


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