Some, such as digitalis and quinine, have been used for medicinal purposes for centuries. The anticancer effects of many of them, however, are only beginning to be explored.
Phytochemicals differ from vitamins and minerals in that they have no known nutritional value.
Some are antioxidants, protecting against harmful cell damage from oxidation. Others perform different functions that help prevent cancer. Today's laboratory pioneers are still deciphering the many ways phytochemicals in foods may offer front-line defenses against cancer. Isothiocyanates, for example, found in cruciferous vegetables like broccoli and cabbage, protect against cancer through their effect on enzymes. Saponins, found in beans and legumes, may prevent cancer cells from multiplying by influencing a genetic material in the cells.