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Vitamin E may counteract effect of free radicals

(Miami University)
Citation: Cancer Weekly, March 22, 1993 p8(2)

Subjects: Vitamin E Physiological aspects
Free radicals (Chemistry) Physiological aspects
Exercise Physiological aspects
Reference #: A13638755

Full Text COPYRIGHT Charles Henderson, Publisher 1993
Miami University


Researchers concede they can't prove its value, but some believe additional vitamin E is a good idea for exercisers worried about potentially dangerous free radicals, which have been implicated in cell damage ranging from cancer and heart disease to aging.


The researchers are looking at signs that exercise increases production of free radicals.


The radicals are unstable oxygen molecules with an extra electron that try to become balanced by latching onto more electrons, setting off a chain of electron -grabbing that batters other molecules. "Right now, as you are breathing air, about 5 percent of the oxygen is breaking down into free radicals," said Helaine M. Alessio, associate professor of exercise physiology at Miami University in Oxford, Ohio. When you exercise, your oxygen consumption easily could increase tenfold, so your production of free radicals could theoretically increase tenfold as well, Alessio said. But researchers don't yet know exactly how much free radicals do increase or what the consequences are, she said.


And one prominent researcher doubts the effects are meaningful in practice. "This is an interesting idea here, and there's no question from these observations that in the short run exercise may yield higher indices of oxidative stress," said Dr. Charles H. Hennekens, professor of medicine and preventive medicine at Harvard Medical School, Cambridge, Massachusetts. But Hennekens says these effects seem to be short -term and overbalanced by the obvious good that exercise does. He notes that exercise is associated with reduced risk of heart disease and some forms of cancer - which works against the argument that free radicals raise an exerciser's risk of those conditions.


To an extent, free radicals are good because they work as part of the white blood cell's defenses against infection and injury, said Lester Packer, professor of molecular and cell biology at the University of California, Berkeley. But they can get out of hand, he said. Free radicals can damage cell membranes and protein, said Robert R. Jenkins, a professor of biology at Ithaca College in Ithaca, New York. "The major concern would be cell damage where free radicals actually enter the nucleus and affect DNA," said Alessio. "Once you do that, you're talking the next generation of cells."


Several antioxidant enzymes work to control oxygen free radicals, according to researcher Li Li Ji of the University of Illinois, Urbana. And it appears that the stress of exercise makes skeletal muscle more efficient in using these enzymes, Ji wrote in Medicine and Science in Sports and Exercise, the journal of the American College of Sports Medicine. The journal published a five-part section on free radicals. Vitamins C and E and the compound beta-carotene also act as antioxidants, but whether exercisers need supplements is unproven, Alessio said.



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