There was a time when the term "free radicals" referred
to left-leaning hippies and wacko political activists
who had yet to be incarcerated for their views. Now the
term brings to mind cancer-causing molecules that bop
around triggering oxidative damage. The fear these free
radicals inspire has sent hordes of people to their pharmacy
shelves in search of supplements like vitamin E that are
rumoured to stave off the damage. But new research suggests
that this strategy may be much more dangerous than the
free radicals themselves.
A team of researchers led by Dr
Edgar Miller, III, at Johns Hopkins University in Baltimore,
MD, used the rigorous statistical muscle of meta-analysis
to examine 19 studies. These gold-standard, randomized,
placebo-controlled trials looked at the effects of supplemental
doses of vitamin E.
The outcome of their analysis supports
the view that high doses are linked with "all-cause
mortality." And, as if that weren't enough, the dose-dependent
increase in risk of death begins at 150 IU/day. Typical
over-the-counter vitamin E pills are 400 IU.
The results were presented in New
Orleans at the annual meeting of the American Heart
Association 2004 Scientific Sessions, and were simultaneously
published as an early release article in the November
10 online issue of the Annals of Internal Medicine.
VITAMIN
E OD
When the researchers analysed the pooled data from 135,967
people, "it was clear that as the vitamin E dose increased,
so does all cause mortality," said Dr Miller at the
presentation. Indeed, at "the most common marketed dose
of 400 IUs, the risk of dying is about 10% higher than
risk among people not taking the vitamin," he states.
"I think people take vitamin E
because they think it's going to make you live longer,
but this [study] doesn't support that," Dr Miller commented
at a press conference following the presentation.
Rather than helping prevent oxidative
damage by free radicals, large doses may overwhelm the
body's innate antioxidant arsenal, according to the
researchers. The resulting cumulative damage to the
body could contribute to the higher mortality evident
in those taking higher doses of vitamin E.
"It doesn't get clearer than that
— don't take it," said Dr Raymond Gibbons, professor
of medicine at the Mayo Clinic, and chair of the New
Orleans meeting's scientific committee. Dr Gibbons has
been urging his patients to refrain from taking vitamin
E pills for years. Not surprisingly, reaction from those
who sell vitamin supplements has been heated.
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