Vitamin E was discovered
at UC Berkeley more than 80 years ago and has been a
star among nutrients for two decades now. In 1994, reacting
to promising research, many professionals began recommending
vitamin E supplements as a possible way to reduce the
risk of heart disease, cancer, and other disorders.
Many people, especially when following a low-fat diet,
don't get much vitamin E from food. There was no evidence
of harm, and the theory that antioxidants such as vitamin
E could prevent or delay chronic diseases was plausible
and exciting. In 2001, however, after reviewing subsequent
clinical trials that had yielded disappointing or conflicting
results, many softened their endorsement of E supplements
and halved earlier recommendations to 200-400 IU a day.
Then in 2003 even more disappointing studies were published,
withdrawing some recommendations altogether.
This change, however, is
not based on the much-publicized meta-analysis
published last November, which concluded that high doses
of vitamin E (more than 400 IU a day) taken long term
may slightly increase the overall risk of dying by about
4%. Lower doses (200 IU or less) did not increase the
risk of dying and may even have had a small protective
effect, though the researchers raised doubts about this.
That analysis, done at Johns Hopkins Medical Institutions,
did not involve any new research. Instead, it combined
and re-analyzed data from 19 clinical trials on vitamin
E supplements from the last decade. Its results made
headlines and caused shock waves, especially among the
13% of Americans who take this vitamin to protect their
health, many of whom tossed their bottles of E.
No
proof of harm
The Hopkins meta-analysis
has not convinced us that vitamin E is dangerous. If
you've been taking E pills, don't fear that
you've harmed yourself on the basis of this paper.
Many researchers have raised questions about the way
the analysis was done. Much of the press coverage overstated
the results.
Moreover, there has been
no solid evidence of harm from vitamin E. Of the 19
studies in the analysis, only one found a statistically
significant risk. Three other recent meta-analyses on
E found no increased risk. And after evaluating hundreds
of studies, the Institute of Medicine of the National
Academy of Sciences, which devises the recommended dietary
allowances (RDAs) and safe upper limits for nutrients,
concluded that the upper limit for vitamin E is 1,000
milligrams (about 1,500 IU) a day. It set the RDA, however,
at just 15 milligrams (about 23 IU) a day.
But
no benefits either
What is clear from the four
meta-analyses and Institute of Medicine report mentioned
above is that there's little or no clinical research
showing that vitamin E supplements are beneficial. Nearly
all the clinical trials on E from the past few years
have yielded negative, inconclusive, or neutral results.
Any time it takes so many studies to find a benefit,
there could be conflicting results down the road.
Other important studies on
E are still underway, and some of them probably will
find benefits. Indeed, in September some reported on
a study that found that vitamins C and E, taken together,
seem to decrease the risk of Alzheimer's. However, there
are still too many unanswered questions: Is one form
of vitamin E supplement preferable? What dose is best?
Should E be taken with other antioxidants? Do you have
to start taking it when you're still healthy? Is it
possible that only the vitamin E in food is beneficial?
The
best way to get E: Do eat foods rich in vitamin
E such as nuts, seeds, vegetable oils, whole grains,
and leafy greens. The first three are high in good fats,
but also calories, so don't go overboard. There is promising
research showing that the E in foods is healthful. And
these foods contain other important nutrients as well.
Basic multivitamins are usually advisable, which typically
contains a little more than the RDA for vitamin E.
Additional
Articles on Vitamin E
