Inhibition of oxidative DNA damage, 8-OHdG, and carbonyl contents in smokers treated with antioxidants (vitamin E, vitamin C, beta-carotene and red ginseng).

The chemopreventive effects of antioxidants (vitamin E, beta-carotene, vitamin C and red ginseng) on oxidative DNA and protein (globin) damages were comparatively investigated in the peripheral blood of smokers (> or = 20 cigarettes/day). Smokers showed a lower baseline level of plasma micronutrients (vitamin C and beta-carotene) (P < 0.01) and higher baseline level of oxidative DNA or protein damage than non-smokers (N = 5; P < 0.05). During daily supplementation of antioxidants (200 IU vitamin of E, 9 mg of beta-carotene, 500 mg of vitamin C, or 1.8 g of red ginseng) for 4 weeks, smokers plasma antioxidant concentrations increased linearly, while their mean levels of 8-hydroxydeoxyguanosine (8-OHdG) and carbonyl contents decreased compared with those in smokers supplemented with a placebo (P < 0.05). Levels of urinary and plasma cotinine remained steady in smokers regardless of supplementation with antioxidants. 8-OHdG and carbonyl content decreased in a time-dependent manner (as the total intake dose increased) after supplementation with vitamin E (8-OHdG, 33.8%; carbonyl content, 43.6%) or red ginseng (8-OHdG, 31.7%; carbonyl content, 21.3%). These preliminary data suggest that supplementation with antioxidants might protect smokers from oxidative damages and could reduce cancer risk or other diseases caused by free radicals associated with smoking.