Magazine article Science News

Antioxidants: Confirming a Heart-Y Role

Magazine article Science News

Antioxidants: Confirming a Heart-Y Role

Article excerpt

In cigarette smokers, vitamin C supplements reduce signs of chemical reactions believed to play a pivotal role in the development of artery-clogging plaque, a new study finds. A second study reports that vitamin C can restore normal functioning to impaired blood vessel walls in otherwise healthy smokers. Together, the reports refine the picture of how antioxidant vitamins combat heart disease.

A wealth of accumulating evidence now implicates free radicals and other oxidants-short-lived, biologically damaging molecular fragments-in aging and a host of chronic diseases (SN: 5/18/96, p. 331; 8/1/92, p. 76). "Because of their very evanescence, [these oxidants] are extraordinarily difficult to measure in the body," notes Garret A. FitzGerald of the University of Pennsylvania Medical Center in Philadelphia.

In 1990, however, a team of researchers led by Jason D. Morrow and L. Jackson Roberts II at Vanderbilt University in Nashville discovered a novel class of chemicals-termed F2-isoprostanes-produced by the oxidation of fats in the body. In the May 4, 1995 New England Journal of Medicine, the scientists showed that smokers produce far higher concentrations of these compounds than nonsmokers do.

That was not surprising, since cigarette smoke can flood the body with copious quantities of oxidants. Moreover, smokers tend to exhaust the body's stores of vitamin C-a premier oxidant quencher-more quickly than nonsmokers. The study's real benefit, Roberts says, was to establish that isoprostanes are stable, highly quantifiable markers of internal oxidation that can be tested outside the body.

FitzGerald's team focused on urinary excretion of one isoprostane, known as 8-epi, to explore how a series of treatments altered internal oxidation among 24 smokers in Dublin. They describe their findings in the July 1 Circulation. During the 3 weeks that six of the volunteers swapped their heavy cigarette habits for nicotine patches, 8-epi concentrations fell about 23 percent; even so, they were about 75 percent higher than concentrations in 24 nonsmokers. …

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