Total antioxidant capacity as a tool to assess redox status: Critical viewand experimental data

The measure of antioxidant capacity (AC) considers the cumulative action of all the antioxidants present in plasma and body fluids, thus providing an integrated parameter rather than the simple sum of measurable antioxidants. The capacity of known and unknown antioxidants and their synergistic inter action is therefore assessed, thus giving an insight into the delicate bala nce in vivo between oxidants and antioxidants. Measuring plasma AC may help in the evaluation of physiological, environmental, and nutritional factors of the redox status in humans. Determining plasma AC may help to identify conditions affecting oxidative status in vivo (e.g., exposure to reactive o xygen species and antioxidant supplementation). Moreover, changes in the pl asma AC after supplementation with galenic antioxidants or with antioxidant -rich foods may provide information on the absorption and bioavailability o f nutritional compounds. Consequently, this review discusses the rationale, interpretation, confounding factors, measurement limits, and human applica tions of the measure of plasma AC. (C) 2000 Elsevier Science Inc.