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Vitamine E en C voorkomen oxidatieschade bij topsport.*
Uit een nieuwe studie door
het bekende Linus Pauling Instituut blijkt dat marathonlopers die 6 weken lang
voor hun wedstrijd extra Vitamine E en C innemen geen oxidatieschade oplopen
door die extreme inspanning.
A new study by researchers in
the Linus Pauling Institute at Oregon State University found that
ultramarathon runners who used supplements of vitamins C and E for six weeks
prior to their races totally prevented the increase in lipid oxidation that is
otherwise associated with extreme exercise.
The type of metabolic damage
observed in these runners is also often found after heart attacks, strokes,
surgery and other traumas, the report noted, and the researchers say this
study provides more evidence for the value of vitamin E supplementation as an
antioxidant that, at the least, can help prevent damaging lipid oxidation and
some of the health concerns associated with it.
The study was just published
in a professional journal, Free Radical Biology and Medicine.
In the controlled research,
the OSU scientists examined 22 runners who performed in a 50-kilometer
"ultramarathon," running more than 30 miles up and down hills near
Corvallis, Ore. Half of the runners were given daily supplements of 1,000
milligrams vitamin C and 400 international units of vitamin E for six weeks
prior to the race, while the other half ate only their normal, healthy diet.
An analysis of
"biomarkers" in the control group that received no supplements
showed significant increases in lipid peroxidation following the race - these
biomarkers were at levels that are often seen after someone has had a heart
attack. The runners taking vitamins C and E were comparatively normal.
Interestingly, the male runners who did not receive supplements continued
their unusually high levels of oxidized lipids for almost a week, while the
metabolism of females returned to normal in a day.
"This study clearly
showed that supplementation with these antioxidant vitamins could help prevent
the significant levels of lipid oxidation that are associated with intense
exercise," said Angela Mastaloudis, an LPI researcher and co-author on
the study. "And it's worth noting that the people who did not take
supplements, but did have a vitamin E intake that would be about the amount
suggested by the federal RDA, did not gain those protective benefits."
According to Mastaloudis and Maret Traber, a co-author and professor with the Linus Pauling Institute, the findings of this study may have ramifications far beyond just people who undergo unusual exercise regimens. Oxidative stress and higher levels of lipid oxidation are seen in a wide range of health problems, ranging from diabetes to heart disease, stroke, Alzheimer's disease, smoking and even obesity, the researchers said.
"Studies such as this are
done with healthy people on good diets facing an unusual stress due to
athletic exertion, but many other people may face similar metabolic stress due
to chronic disease," Traber said. "We often can't do dietary studies
with people who are very ill, due to ethical concerns, so we used marathon
runners to learn more about the effects of stress and ways to prevent damage
from it. These athletes in a race can have a 10- to 20-times increase in whole
body oxygen consumption."
Traber and Mastaloudis said
they wanted to stress that antioxidant vitamins are no substitute for a
healthy lifestyle, balanced diet, proper weight and regular exercise.
"However, this study does
suggest that people who have high levels of oxidative stress and lipid
oxidation due to other chronic health problems might benefit from supplements
of vitamin E that are higher than the current RDA for this vitamin,"
Traber said.
Lipids are fats, the
researchers said, which in the body are found in cell membranes. When they are
oxidized, however, they can ultimately cause a whole range of health concerns,
such as damage to cells, increased blood pressure and blood clotting, plaque
formation in artery walls, and blood vessel constriction.
"One of the things we're
finding more and more is that different antioxidants have fairly specific jobs
that often don't overlap all that much," Traber said. "For instance,
some claims have been made that vitamin E can play a role in preventing DNA
damage, muscle fatigue, muscle damage or improved performance, and we simply
don't find much evidence to support that."
But when it comes to
preventing lipid oxidation and the health concerns associated with that,
vitamin E may be of profound benefit, the OSU researchers said.
"I think it's pretty safe
to say, at this point, that marathon runners should absolutely be taking
supplements of vitamin E," Traber said. "A larger question is to
determine who else could benefit."
It might be quite a few
people, the OSU scientists said. For one thing, various studies have shown
that less than 20 percent of the American public gets even the RDA of vitamin
E, let alone takes a supplement. And this vitamin is most commonly obtained
from fat and oils, which are increasingly being reduced as more people move
towards a low-fat diet.
Traber is one of the nation's
leading experts on vitamin E, and has served on federal panels studying the
recommended levels of this vitamin.
The most recent RDA recommendation, Traber said, is based largely on data that is decades old, and does not really explore the optimal intake for people who have depressed levels of micronutrients for various reasons, such as athletic exertion, heart disease, other degenerative diseases, or simple lack of physical activity. (juli 2004)