Oxidative DNA damage, antioxidants and DNA repair: applications of the comet assay

Estimates of background levels of oxidative base damage in human white bloo d cells vary enormously, from 300 down to 0.4 molecules of 8-oxoguanine per 10(6) guanines. An EC-funded Concerted Action, the European Standards Comm ittee on Oxidative DNA Damage, is currently attempting to resolve the discr epancy and to agree a realistic estimate of basal endogenous oxidation. Oxi dation of lymphocyte DNA is a useful marker of oxidative stress, and this c an be decreased by supplementation with pure antioxidants or with foods ric h in antioxidants. The steady-state level of DNA oxidation is ultimately co ntrolled by the process of DNA repair; the extent to which this varies betw een individuals has vet to be established.