124 - Anti-genotoxic effects of fruit and vegetables and their constituents

Abstract

A diet rich in fruit and vegetables may decrease the risk of cancer. Decrease of endogenous or exogenous genotoxicity by fruit and vegetables may be partly responsible for this effect. Using the Comet assay in a number of in vivo studies, we attempted to identify the fruit and vegetable species, their extracts or isolated compounds able to decrease endogenously or exogenously-induced DNA damage. We found that consumption of apples protected against formation of endogenously oxidized purine bases and increased capacity to protect DNA in lymphocytes in humans. Cloudy apple juice (750 ml, 2 weeks) also showed an increased capacity to protect DNA in humans. Using the1,2-dimethylhydrazine-rat model of carcinogenesis, we demonstrated the anti-genotoxic and anti-carcinogenetic effects of cloudy apple juice but not their fractions. We also observed a significant reduction of irinotecan-induced DNA-strand breaks after a pre-treatment with isolated anthocyans (cyanidin, cyanidin-3-glucoside) and a blackberry extract in rats and demonstrated that daily consumption of tomato oleoresin containing about 15 mg of lycopene decreased endogenous DNA damage. In contrast, 200 g broccoli for 4 weeks or 330 ml carrot juice for 2 weeks had no effect in humans. Also, consumption of 8 servings (about 800 g) of different commonly consumed fruit and vegetables for 4 weeks showed no effect on DNA damage in lymphocytes in humans. These observations indicate that the kind of fruit or vegetable (e.g. apples, blackberries, tomato products) rather than the total amount of different commonly consumed fruit and vegetables is of essential importance for the anti-genotoxic effects in humans.