8-6 |
Use of oxidative stress biomarkers to evaluate dietary antioxidants in vivo |
B. FREI, Linus Pauling Institute, Oregon State Univ., 571 Weniger Hall, Corvallis, OR 97331-6512 Oxidative stress leading to oxidative damage to biological macromolecules has been implicated in many human chronic diseases, including cardiovascular diseases, cancer, cataractogenesis, and age-related neurodegenerative diseases, as well as the aging process itself. Oxidative damage in vivo is likely to occur at only a few specific sites or tissues at any given time. Since oxidatively damaged biomolecules are subject to detoxification and metabolism, and may also be ingested from foods, suitable biomarkers of in vivo oxidative damage have proven difficult to identify and validate. Among the most commonly used in vivo markers of oxidative lipid, protein, and DNA damage, respectively, are F2-isoprostanes, protein carbonyls, and 8-oxo-7,8-dihydro-2'-deoxyguanosine. A limited number of reliable studies have used these oxidative stress biomarkers to assess the effects of supplementation with antioxidant vitamins on oxidative damage in humans. The data reviewed indicate that treating subjects who are under increased oxidative stress, in particular smokers, with vitamins C or E is beneficial in reducing oxidative damage to lipids and DNA. A study claiming that vitamin C supplementation causes, rather than prevents, oxidative DNA damage in humans has been shown to be seriously flawed due to ex vivo oxidation artifacts. There is increasing evidence, based on isoprostane measurements, that vitamin C and vitamin E supplementation inhibits lipid peroxidation in patients with diabetes, hepatic cirrhosis, or hypercholesterolemia, and possibly even in healthy subjects. Very few data are available on the role of antioxidants in reducing oxidative protein damage in humans. Future research needs to establish the specificity and accuracy of the oxidative stress biomarkers currently used, their causal relationship to disease outcome, develop new biomarkers, and confirm the efficacy of antioxidant vitamins to limit oxidative damage in humans.
Session 8, Oxidation in heterogenous foods and biological tissues: Impact on food quality and health
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