Energy restriction and oxidative DNA damage in humans.

The cancer-preventive effect of energy restriction in rodents has been related to a decrease in oxidative damage to DNA. We have investigated the effect of energy restriction on the rate of oxidative DNA modification estimated from the urinary excretion of the repair product, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), in healthy, normal weight men. Before and after 10 weeks on a diet containing 80 (n = 16) or 100% (n = 8) of the estimated weight-maintaining energy, resting metabolic rate (RMR) was measured and 24-h urine was collected for 8-oxodG determination by HPLC. During the study, the weight loss was 10 and 2.5% of the initial weight, mostly in terms of fat, and the RMR decreased by 13 and 8% in the energy-restricted and control groups, respectively. With the use of t tests there was no significant difference within or between groups with respect to 8-oxodG excretion. However, if RMR was included as a covariate in multifactorial ANOVA, an average relative 17% (2-31%; 95% confidence interval) increase in 8-oxodG excretion in the energy-restricted group was significantly different from the corresponding value of the control group (P < 0.02). In the energy-restricted group the change in 8-oxodG excretion was correlated closely with the decrease in RMR (r = 0.63; P = 0.013). In the present study, 20% energy restriction for 10 weeks did not reduce oxidative DNA damage; we question a beneficial effect on cancer risk in normal weight humans.(ABSTRACT TRUNCATED AT 250 WORDS)