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Most of the excitement, however, is being generated by a group of vitamins -- C, E and beta carotene, the chemical parent of vitamin A -- that are known as antioxidants. These nutrients appear to be able to defuse the volatile toxic molecules, known as oxygen-free radicals, that are a byproduct of normal metabolism in cells. These molecules are also created in the body by exposure to sunlight, X rays, ozone, tobacco smoke, car exhaust and other environmental pollutants.
Free radicals are cellular renegades; they wreak havoc by damaging DNA, altering biochemical compounds, corroding cell membranes and killing cells outright. Such molecular mayhem, scientists increasingly believe, plays a major role in the development of ailments like cancer, heart or lung disease and cataracts. Many researchers are convinced that the cumulative effects of free radicals also underlie the gradual deterioration that is the hallmark of aging in all individuals, healthy as well as sick. Antioxidants, studies suggest, might help stem the damage by neutralizing free radicals. In effect they perform as cellular sheriffs, collaring the radicals and hauling them away.
Supporters of this theory speculate that antioxidants may one day revolutionize health care. Biochemist William Pryor, director of the Biodynamics Institute at Louisiana State University, foresees screening people through a simple urine, blood or breath test to assess how much damage free radicals have done to tissue, much as patients today are screened for high cholesterol. "If you can predict who is most susceptible to oxidative stress," notes Pryor, "you can treat them with antioxidants more effectively." Ultimately, says biochemist Bruce Ames at the University of California, Berkeley, "we're going to be able to get people to live a lot longer than anyone thinks."
In that brave new world, people might pop vitamins C and E to deter the development of cataracts, the clouding of the lens in the eye that afflicts 20% of Americans over 65. Patients taking high doses of both vitamins appear to reduce the risk of cataracts by at least 50%, according to a Canadian study. Vitamin C may be especially efficient because it concentrates in the eye. Scientists at the National Eye Institute estimate that if cataract ; development could be delayed by 10 years, about half of cataract surgery could be eliminated.
Vitamin E may be particularly helpful in preventing free radicals from injuring the heart. Doctors speculate that giving the vitamin to patients during or shortly after a heart attack might help preserve heart muscle. One clue from a study at Toronto General Hospital: rabbits injected with vitamin E within two hours of a heart attack showed 78% less damage to heart tissue than was expected. The vitamin appears to speed recovery in patients who have had coronary-bypass operations, suggesting that nutrient supplements may one day become part of standard pre-op procedure.