Effect of dietary phytochemicals on cancer development (review).

Vegetables, fruits, and whole grains contain a wide variety of phytochemicals that have the potential to modulate cancer development. There are many biologically plausible reasons why consumption of plant foods might slow or prevent the appearance of cancer. These include the presence in plant foods of such potentially anticarcinogenic substances as carotenoids, chlorophyll, flavonoids, indole, isothiocyanate, polyphenolic compounds, protease inhibitors, sulfides, and terpens. The specific mechanisms of action of most phytochemicals in cancer prevention are not yet clear but appear to be varied. Considering the large number and variety of dietary phytochemicals, their interactive effects on cancer risk may be extremely difficult to assess. Phytochemicals can inhibit carcinogenesis by inhibiting phase I enzymes, and induction of phase II enzymes, scavenge DNA reactive agents, suppress the abnormal proliferation of early, preneoplastic lesions, and inhibit certain properties of the cancer cell.