No Differences in DNA Damage and Antioxidant Capacity Between Intervention Groups of Healthy, Nonsmoking Men Receiving 2, 5, or 8 Servings/Day of Vegetables and Fruit

Abstract

The effects of different intake levels of vegetables and fruit (VF) on some cancer-relevant biomarkers such as DNA damage and oxidative stress were investigated. In a randomized controlled trial, 64 nonsmoking male subjects were asked to consume a diet with 2 servings of VF/day for 4 wk. Then subjects were randomly assigned to 1 of 3 groups with either a low (2 servings/day), medium (5 servings/day), or high (8 servings/day) intake level of VF for another 4 wk. At the end of study, the plasma lutein, zeaxanthin, α -carotene, and β-carotene but not cryptoxanthin and lycopene concentrations were significantly higher in subjects consuming 8 servings/day than in those receiving 2 servings/day. Different levels of VF consumption and plasma carotenoid concentrations did not result in differences in the levels of endogenous DNA strand breaks, oxidative DNA damage, antigenotoxic capacity of lymphocytes, plasma markers for lipid peroxidation (malondialdehyde, 8-iso-prostaglandin-F_2α) and antioxidant capacity [trolox-equivalent antioxidant capacity assay]. Thus, although consumption of 8 servings vs 2 servings/day of VF for 4 wk significantly increased the carotenoid level in plasma, there were no differences in DNA damage, lipid peroxidation, and antioxidant capacity markers among healthy, well-nourished, nonsmoking men.

ACKNOWLEDGMENTS

We thank E. Hoch, Ute Stadler-Prayle, R. Lambertz, and B. Mathony-Hohlschuh for their excellent technical assistance. Tomato and carrot juices were provided by Schoenenberger Pflanzensäfte GmbH, Magstadt, Germany, which is gratefully acknowledged. This study was supported by a grant from the World Cancer Research Fund (2002/15).

Notes

^a Abbreviations are as follows: BMI, body mass index; VF, vegetables and fruit. Values were calculated based on the food composition database of the German Food Code BLSII.2 at baseline (before the VF restriction (≤2 servings/day). There were no significant differences between groups. No significant changes in BMI, energy, and macronutrient (protein, carbohydrates, fat) intake were observed during the intervention (for additional information see Ref. 11). Data are from Ref. 11.

^b n = 21.

^a Values were calculated by using a dietary record specifically assessing the daily intake of vegetables and fruit (VF). One serving = 100 g of VF or 200 ml juice. Vegetable intake included carrots, green beans, peas, broccoli, zucchini, tomato, kohlrabi, brussels sprouts, red cabbage, cauliflower, spinach, corn, and salsifies. Salad intake included lettuce, tomato, carrot, corn, radish, cucumber, fennel, and cabbage. Fruit intake consisted of apples, pears, kiwi, banana, peaches, nectarines, cherries, strawberries, and red currants. All groups were instructed to consume 2 servings/day during Weeks 1–4. Data from Ref. 11.

*In the comet assay, the amount of damaged DNA was expressed as the percentage of DNA in the tail (TI).

*P < 0.05 vs. 2 servings by ANOVA and Dunnett's post hoc test.

^a Data are from Ref. 11.

^b P = 0.08 vs. baseline with 2 servings/d by Student's t-test.