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The goal of this study was to test the hypothesis that increased consumption of vegetables and fruit would reduce markers of oxidative cellular damage that can be assessed in blood or urine. Twenty-eight women participated in a 14 day dietary intervention. The primary end-points assessed were: 8-hydroxydeoxyguanosine (8-OHdG) in DNA isolated from peripheral lymphocytes, determined by HPLC with electrochemical detection; 8-OHdG excreted in urine, measured by ELISA; malondialdehyde (MDA) in urine, measured by fluorimetric detection following derivatization with thiobarituric acid and separation via HPLC; urinary 8-isoprostane F-2alpha (8-EPG) detected by ELISA. Pre- and post-intervention plasma levels of selected carotenoids were determined by HPLC. Subjects were free living and consumed a completely defined recipe-based diet that increased their average daily consumption of vegetables and fruit from 5.8 servings at baseline to 12.0 servings throughout the intervention. Overall, the level of 8-OHdG in DNA isolated from lymphocytes and in urine and the level of 8-EPG in urine were reduced by the intervention, whereas urine concentrations of MDA were minimally affected. The reduction in lymphocyte 8-OHdG was greater in magnitude (32 versus 5%) in individuals with lower average pre-intervention levels of plasma alpha-carotene (56 ng/ml) than in individuals with higher average pre-intervention plasma levels of alpha-carotene (148 ng/ml). The results of this study indicate that consumption of a diet that significantly increased vegetable and fruit intake from a diverse number of botanical families resulted in significant reductions in markers of oxidative cellular damage to DNA and lipids.