Cancer chemoprevention by phytochemicals may be one of the most feasible approaches for cancer control. For example, phytochemicals obtained from vegetables, fruits, spices, teas, herbs and medicinal plants, such as carotenoids, phenolic compounds and terpenoids, have been proven to suppress experimental carcinogenesis in various organs. These candidates should be evaluated by intervention studies, before acceptance as cancer preventive agents for human application. Phytochemicals may also be useful to develop “designer foods” or “functional foods” for cancer prevention. We are now planning animal foods, such as meats, eggs and milk, which contain anti-carcinogenic phytochemicals. In prototype experiments, expression of genes for synthesis of phytochemicals, such as phytoene and limonene, has been successful in cultured animal cells.
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