Oxidative Damage and Defense
Jacob RA; Burri BJ
American Journal of Clinical Nutrition,
1996 Jun, 63(6):985S-990S
Abstract:
Increased
production of reactive oxygen species is a feature of most, if
not all, human disease, including cardiovascular disease and
cancer. Dietary antioxidants may be especially important in
protecting against human diseases associated with free radical
damage to cellular DNA, lipids, and proteins. Ascorbic acid is an
effective water-soluble antioxidant, and epidemiologic studies
suggest that increased ascorbate nutriture is associated with
reduced risk of some degenerative diseases, especially cancer and
eye cataracts.
Population studies have also shown that high vitamin E intakes are associated with decreased risk of coronary heart disease, possibly as a result of inhibition of atherogenic forms of oxidized low-density lipoprotein.
Recent data suggest that beta-carotene provides protection against lipid peroxidation in humans, as well as provitamin A activity. Yet, present data are not sufficient to quantitate micronutrient requirements needed to protect against oxidative damage. The antioxidant roles of many food constituents, such as polyphenols, have not been clarified. Most antioxidants can act as prooxidants under certain conditions, and more research is needed to determine the occurrence and importance of this in vivo.
The few controlled intervention trials carried out so far have shown mixed results as to the potential of antioxidant supplements for reducing the incidence of chronic diseases. Definitive recommendations on antioxidant intakes for disease prevention must await evidence from controlled studies and intervention trials, some currently in progress.
Overall,
the present data suggest that protection against oxidative damage
and related disease is best served by the variety of antioxidant
substances found in fruit and vegetables. 
