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Diet antioxidant capacity: Relationship to oxidative stress and health
R. L. PRIOR (1). (1) University of Arkansas, Searcy, AR, U.S.A.
Oxidative stress has been implicated in the etiology of many chronic and degenerative diseases, and in the aging process suggesting that antioxidants, both endogenously and exogenously, are necessary to protect cellular components from oxidative damage. Recent research studies have demonstrated that increased dietary intake of total antioxidant capacity is associated with reduced risk for ischemic stroke, hypertension, gastric cancer, endometrial cancer, and improved pulmonary function. Furthermore, consumption of antioxidant rich foods can reverse the postprandial oxidative stress resulting from consumption of an antioxidant free meal. Thus, consumption of dietary antioxidants is important with each meal. Sufficient research data to establish definite reference dietary intakes (RDI), as has been done for vitamins A, C, and E, is not possible for total dietary antioxidants (measured by Oxygen Radical Absorption Capacity (ORAC) or any other antioxidant capacity assay). However, some recommendations can be made based upon recent epidemiological studies and studies of absorption of antioxidant phytochemicals and their effects on<i> in vivo</i> antioxidant status and their ability to prevent postprandial oxidative stress. ORAC intakes of at least 12,000 units (1 unit=1 micromole Trolox Equivalent)) or more may provide reduced risk for the diseases studied and intakes of less than ~7000 units of ORAC per day may lead to increased risk for some diseases. These recommendations are in line with a daily consumption of 7 to 10 servings of fruits/vegetables/grains with some of those foods containing higher amounts of ORAC. Because of differences in the ability of different phytochemicals to quench free radicals, consumption of a mixture of high antioxidant foods would be prudent to provide for this variability.
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