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Many health benefits are associated with a high dietary intake of vegetables and fruit (VF); however, little effort has been expended to determine whether the botanical families from which high-VF diets are formulated affect their biological activities. The objective of this study was to determine whether the botanical diversity of high-VF diets alters the response in oxidative biomarkers for lipid peroxidation and DNA oxidation. Two diets were developed that varied in botanical diversity and provided 8-10 servings of VF/d. The high botanical diversity diet (HBD) included foods from the 18 botanical families that induced a reduction in oxidative damage of lipids or DNA. The low botanical diversity diet (LBD) emphasized 5 of these botanical families based on reports that their bioactive components had high antioxidant activity. A total of 106 women completed the study. Participants consumed 9.1 +/- 2.6 and 8.3 +/- 2.1 servings of VF/d with the LBD and HBD diets. Only the HBD diet induced a significant reduction in DNA oxidation (P < 0.05). Both the LBD and the HBD diets were associated with a reduction in lipid peroxidation (P < 0.01). These findings indicate that botanical diversity plays a role in determining the bioactivity of high-VF diets and that smaller amounts of many phytochemicals may have greater beneficial effects than larger amounts of fewer phytochemicals.

Background: Health benefits associated with diets rich in vegetables and fruit (VF) are often attributed to the antioxidant activity of their constituent phytochemicals. However, in vivo evidence that VF actually reduce markers of oxidative stress is limited., Objective: An 8-wk dietary intervention was conducted to test the hypothesis that increased VF consumption decreases oxidative stress. Urinary excretion of 8-isoprostane F2alpha (8-iso-PGF2alpha) was used as an index of whole-body lipid peroxidation., Design: The diets evaluated had comparable amounts of all macronutrients but varied in their content of VF. After a 2-wk low-VF (3.0 servings/d) run-in diet, 246 women were randomly assigned to receive either 3.6 (low) or 9.2 (high) servings VF/d. The low-VF group was switched to the high-VF diet during the final 2 wk of the study. Blood and first-void urine specimens were obtained at baseline and at 2-wk intervals thereafter., Results: The run-in diet reduced 8-iso-PGF2alpha concentrations by 33% (P < 0.0001). The excretion of 8-iso-PGF2alpha with the low-VF diet remained the same as that with the run-in diet, whereas urinary concentrations of 8-iso-PGF2alpha were further reduced (P < 0.01) by the high-VF diet, either fed throughout the study or when the diet was switched from low to high VF (P = 0.05). The greatest reductions in 8-iso-PGF2alpha were observed in subjects in the highest quartile of baseline concentrations of 8-iso-PGF2alpha., Conclusions: A significant reduction in the excretion of 8-iso-PGF2alpha was induced by the run-in diet and the high-VF diet. The degree of reduction was related to the subject's baseline urinary concentration of 8-iso-PGF2alpha.

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.