Abstract
Phytonutrients in plants play a great role in their protection against certain
bacteria, viruses, and fungi resulting from certain detoxification processes within the
plant. There are many recommendations to increase the intake of high amounts of fresh
colored vegetables and fruits, besides whole grains (cereals) and beans, which contain
phytoconstituents to lower the risk of certain cancers, diabetes and hypertension, in
addition to certain heart diseases. The effect of phytonutrients differs according to their
chemical class and amount. They may act as antioxidants which prevent the effect of
carcinogens on the healthy body. The sources constituents and mechanisms of the
phytonutrients are summarized in this chapter.