The effect of dietary lycopene on bioavailability, tissue distribution, in vivo antioxidant properties and colonic preneoplasia in rats

Recent studies have suggested a protective role for lycopene, an antioxidant carotenoid, in the prevention of chronic diseases including cancer and coronary heart disease. Tomatoes and tomato products are the major dietary source of lycopene. The aim of this study was to investigate the bioavailability, tissue distribution, and the in vivo antioxidant properties of lycopene and its role in colon carcinogenesis. Male Fischer 344 rats were used in this study. Lycopene in the form of 6% oleoresin was incorporated into an AIN93M diet at a concentration of 10 ppm lycopene. Azoxymethane (AOM) was used as-the colon specific chemical carcinogen. Serum and tissue lycopene levels were measured as estimates of lycopene uptake and tissue distribution. Serum TBARS and thiols were measured as indicators of lipid and protein oxidation. Incidence and size of aberrant crypt foci (ACF) were measured as preneoplastic markers. Dietary lycopene was absorbed and distributed to various tissues. An increase in serum thiols and a decrease in serum TBARS was observed in rats fed the lycopene diet. Incidence of ACF in lycopene fed rats showed a trend towards reduced numbers and size. Effects were more pronounced when lycopene was fed during the promotion stage than during the initiation stage. Based on these results it is concluded that dietary lycopene is absorbed by rats and distributed to various tissues. It acts as an antioxidant in reducing oxidation and thereby may protect against AOM induced ACF incidence, Dietary lycopene may play an important role in protecting against oxidative stress and colon carcinogenesis. (C) 1999 Elsevier Science Inc.