Diet modification affects DNA oxidative damage in healthy humans

DNA 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a promising biomarker for oxidative damage. We assessed its responsiveness to diet in 32 nonsmoking, healthy subjects (12 male, 20 female) aged 31 +/- 7.6 years. They consumed two liquid formula diets (Ensures) as the sole source of nutrition for 10-d in a randomized crossover design, with 5-d control solid food diets as washout before each liquid diet period. Reformulated Ensure (Re-En) had a vitamin E/ PUFA of 3.5 compared to standard Ensure (En) of 1.1. We hypothesized that subjects would have lower leukocyte 8-OHdG/deoxyguanosine (dG) ratios while consuming Re-En compared to En. But 8-OHdG/dG ratios did not change with the consumption of either Re-En or En. The mean ratios of 8-OHdG/dG after 10 days of Re-En and En consumption were (2.12 +/- 0.68) X 10(-5) and (2.16 +/- 0.63) X 10(-5), respectively. However, there was a 22% decrease in 8-OHdG/dG by the end of the study and a significant downward trend of leukocyte 8-OHdG among all subjects throughout all nutrient-rich diet phases as the study progressed (Test for trend: p = .04; paired t-test: p = .07). Because all the experimental diets provided antioxidant nutrients at higher quantities than typically consumed by a U.S. age-matched population, this study adds to the few in vivo studies that show a decrease in DNA damage in healthy nonsmoking subjects through dietary intervention. (C) 1999 Elsevier Science Inc.