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Oxidative cell damage is involved in the pathogenesis of atherosclerosis, cancer, diabetes and other diseases. Uptake of fruit juice with especially high content of antioxidant flavonoids/polyphenols, might reduce oxidative cell damage. Therefore, an intervention study was performed with a red mixed berry juice [trolox equivalent antioxidative capacity (TEAC): 19.1 mmol/L trolox] and a corresponding polyphenol-depleted juice (polyphenols largely removed, TEAC 2.4 mmol/L trolox), serving as control. After a 3-week run-in period, 18 male probands daily consumed 700 mL juice, and 9 consumed control juice, in a 4-week intervention, followed by a 3-week wash-out. Samples were collected weekly to analyze DNA damage (comet assay), lipid peroxidation (plasma malondialdehyde: HPLC/fluorescence; urinary isoprostanes: GC-MS), blood glutathione (photometrically), DNA-binding activity of nuclear factor-kappaB (ELISA) and plasma carotenoid/alpha-tocopherol levels (HPLC-DAD). During intervention with the fruit juice, a decrease of oxidative DNA damage (p<5x10(-4)) and an increase of reduced glutathione (p<5x10(-4)) and of glutathione status (p<0.05) were observed, which returned to the run-in levels in the subsequent wash-out phase. The other biomarkers were not significantly modulated by the juice supplement. Intervention with the control juice did not result in reduction of oxidative damage. In conclusion, the fruit juice clearly reduces oxidative cell damage in healthy probands.

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Apple juice containing high amounts of antioxidative polyphenols might protect the intestine against oxidative cell damage. We investigated the preventive effectiveness of polyphenolic juice extracts of different origins (cider and table apples) in comparison to their major constituents in human colon cell lines (Caco-2, HT29). Parameters studied were (oxidative) DNA damage (Comet assay), glutathione level (photometric kinetic assay), cellular redox status (dichlorofluorescein assay) and antioxidant capacity. The extracts (50-250 microg/mL) modulated DNA damage and redox status in a concentration-dependent manner at 24-h incubation. The pomace extraction technology, applied for juice preparation, and the preferential selection of cider apple varieties influenced the polyphenolic pattern and increased the biological effectiveness of the extracts. The preventive potential of major juice constituents (1-100 microM, 24 h) strongly differed: rutin, epicatechin and caffeic acid clearly reduced (oxidative) DNA damage (Caco-2), chlorogenic acid efficiently decreased cellular reactive oxygen species level (HT29, Caco-2). The aglyca quercetin and phloretin exhibited the highest preventive/antioxidant capacity in all assays. The stability of the compounds inversely correlated with their preventive effectiveness and might contribute to the observed cell specific sensitivities. In conclusion, apple juice extracts distinctly reduce oxidative cell damage in human colon cell lines, an effect, which in part can be accounted for by their major constituents.

Epidemiological and experimental evidence increasingly suggests coffee consumption to be correlated to prevention or delay of degenerative diseases connected with oxidative cellular stress. In an intervention study comprising 33 healthy volunteers, we examined DNA-protective and antioxidative effects exerted in vivo by daily ingestion of 750 mL of freshly brewed coffee rich in both green coffee bean constituents as well as roast products. The study design encompassed an initial 4 wk of wash-out, followed by 4 wk of coffee intake and 4 wk of second wash-out. At the start and after each study phase blood samples were taken to monitor biomarkers of oxidative stress response. In addition, body weight/composition and intake of energy/nutrients were recorded. In the coffee ingestion period, the primary endpoint, oxidative DNA damage as measured by the Comet assay (± FPG), was markedly reduced (p<0.001). Glutathione level (p<0.05) and GSR-activity (p<0.01) were elevated. Body weight (p<0.01)/body fat (p<0.05) and energy (p<0.001)/nutrient (p<0.001-0.05) intake were reduced. Our results allow to conclude that daily consumption of 3-4 cups of brew from a special Arabica coffee exerts health beneficial effects, as evidenced by reduced oxidative damage, body fat mass and energy/nutrient uptake.