Chemoprotective substances comprise a large (broad) group of natural substances occurring in plant foods. In humans, they exert a lot (plenty) of biological effects mostly by having a favourable influence on the health, especially as anticarcinogens and antiatherogenic agens. Antioxidant defense mechanisms as well as a stimulation and/or inhibition of enzymes engaged in various metabolic or regulation processes such as controlling the detoxification activities, signal transduction, cell division and apoptosis and lipid metabolism are of the particular significance regarding the biological activites of these substances. A support and promotion of health through prevention of cardiovascular and tumor diseases and the reduction of the other health risks is a very real consequence of sufi‘icient and regular intake offood containing the chemoprotective factors.

Keywords: Chemoprotective substances; Antioxidants; Anticancerogens; Fruit; Vegetables