[The role of dietary plant polyphenols in health maintenance].

Plant polyphenols are typical representatives of natural substances in foods of plant origin, in particular in fruit, tea and vegetables. They display multiple structure-conditioned interactions with various biomolecules. Their general property is the antioxidant and chelating effect and modulation of activity of various enzyme systems. In the diet they act mostly as health promoting factors during various chemical and physical stresses of the organism. They are antiatherogenic and anticarcinogenic, on the principle of inhibition of oxidative destruction of various oxylabel biological structures, inhibition of processes of bioactivation of carcinogens, blocking LDL oxidation and stimulating the activity of antioxidant and detoxication enzymes. Some of them have mutagenic properties in genotoxicity tests (quercetin, colours of red wine, phenolic acids of coffee), however, the results of animal experiments and epidemiological studies do not confirm the risk of neoplastic disease in subjects with a normal intake of these substances. The biological activity of plant polyphenols is part of the activity of other chemopreventive dietary constituents and essential nutrients. In this complex polyphenols act in many ways on the principle of synergism. The use of the health promoting properties of polyphenols isolate from plants and their administration in a pure state is not foreseen. However, under conditions it is desirable to increase the consumption of foods which are important sources of these substances.