[The role of alimentary oxidants and antioxidants in carcinogenesis]

Malignancies have a distinguished role among leading causes of death around the world. As a result of more effective preventive efforts of cardiovascular diseases malignancies will reach the top of death statistics in the near future. The increased incidence of malignant tumors may be attributed to smoking, in temperate alcohol abuse, as well as inappropriate nutrition. Inappropriate nutrition is thought to be responsible for the development of about 30-50% of malignancies. In the present review the authors analyze the uniform theory of carcinogenesis and the possible mechanisms by which certain nutritive factors may interfere with the complex process of carcinogenesis. The mechanism of "oxidative stress" is detailed, in particular the impact of prooxidants (also referred to as free radicals) on tumor development and the central role of lipid peroxidation. In addition to alimentary free radicals the relevance of alcohol abuse in carcinogenesis is also studied. Against the undesirable free radical reactions a complex natural antioxidant (free radical scavenger) system exists, that is responsible for anticarcinogenesis. The authors introduce the dietary antioxidants, their known effects of mechanisms, and their possible role in chemoprevention and therapy of malignancies, based on several experimental and epidemiological data.