The diversity and depth of the body's antioxidant protection system is
reviewed. Components of both endogenous and exogenous origins contrib
ute protection, and new data suggests that some components interact to
spare or replace each other. Evidence from both animal and human stud
ies shows that glutathione and vitamin C can act in concert to allevia
te a variety of oxidant stresses. results from in vitro and animal stu
dies 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 wh
ich 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 e
merging picture of synergisms and interactions suggests that antioxida
nt protection may be more flexible and efficient than indicated by stu
dies of single nutrient effects. The apparent versatility of the oxida
nt defense system implys that it is capable of taking advantage of div
erse antioxidants provided by the diet, as well as excesses of a parti
cular antioxidant nutrient.