Abstract
Carotenoids are natural pigments of plant origin and have been expected to act as dietary anti-carcinogen. However, large-scale human intervention studies started in 1980's did not support the idea that beta-carotene, the most popular carotenoid in plant foods, is helpful in cancer prevention. Thus, other carotenoids including lycopene and xanthophylls should be paied more attention, because human diet contains a variety of such carotenoids. So many animal studies strongly suggest that these carotenoids, alone or in mixture, are effective in lower incidence of tumor formation. These antitumorigenic effects of carotenoids observed in animal studies must be explained mechanistically in terms of their actions on cell propagation and metabolism. Recently, effects of carotenoids on cell proliferation and differentiation have been reported. Recent our findings on oxidative cleavage of carotenoids, effects of oxidized carotenoid and diverse dietary carotenoids against cancer cells, and their absorption are described.
