Though the mechanism is not completely clear, phytochemicals' actions may protect us from a host of diseases. Some of these beneficial chemicals block various hormone actions and metabolic pathways that are associated with the development of cancer and heart disease, and other chemicals stimulate protective enzymes.
Phytochemicals are in plants and plant-derived foods.
They are naturally occurring, non-nutritive chemicals. The phytochemicals appear to work alone and in combination, and perhaps in conjunction with vitamins and other nutrients in food, to prevent, halt or lessen disease. The phytochemical is often found in the coloring agent in fruits and vegetables, so eating the brighter colored types may have benefits. However, there are also several beneficial phytochemicals in colorless or less colorful fruits and vegetables as well. For example, onions and corn are both full of phytochemicals.