THE INTEGRATED ANTIOXIDANT SYSTEM

The diversity and depth of the body's antioxidant protection system is reviewed. Components of both endogenous and exogenous origins contribute protection, and new data suggests that some components interact to spare or replace each other. Evidence from both animal and human studies shows that glutathione and vitamin C can act in concert to alleviate a variety of oxidant stresses. results from in vitro and animal studies indicate that vitamin C regenerates tocopherol in the lipid phase, but this interaction has not yet been shown to be important to human nutrition and metabolism. Newer evidence suggests that beta-carotene and tocopherol may act synergistically against lipid peroxidation, and the polyphenols, such as flavonoids provide antioxidant protection which is enhanced by vitamin C. The diverse roles of iron and copper in redox biochemistry is illustrated by their incorporation in protective metalloenzymes and by some proposed interactions with vitamins. The emerging picture of synergisms and interactions suggests that antioxidant protection may be more flexible and efficient than indicated by studies of single nutrient effects. The apparent versatility of the oxidant defense system implys that it is capable of taking advantage of diverse antioxidants provided by the diet, as well as excesses of a particular antioxidant nutrient.