Interní Med. 2009; 11(1): 30-33

Free radicals, antioxidants and ageing

MUDr. Jan Pláteník Ph.D

Ústav lékařské biochemie 1. LF UK, Praha

The aerobic metabolism inevitably involves production of oxygen radicals. Oxidative damage to biomolecules has to be counteracted

by antioxidant defense. Oxidative stress has been implicated in pathogenesis of many inflammatory and degenerative diseases; and

accumulation of errors of body antioxidant defense and repair systems is the very mechanism of physiological ageing. However, dietary

supplementation of antioxidant vitamins C, E and also beta-carotene and selenium, which was subject of large and repetitive studies,

brings clear benefits only in cases of dietary deficiencies, otherwise is either ineffective, or even harmful. The reasons for this antioxidant

paradox should be sought in complexity of the body antioxidant defense systems, of which the low-molecular – weight antioxidants

represent only a small component, and in further complex interactions of the used compounds with human body. Certain effects on

ageing can perhaps be offered by caloric restriction and the stress reaction (oxidative stress inducing resistance to further stress, e.g.

physical exercise). Eating fruits and vegetables is beneficial to human health probably due to contents of antioxidant phenols. Extra

supplementation with vitamin C, E, and beta-carotene in persons on a normal diet does not seem to be medically justified at present. Only

smokers need higher doses of vitamin C, on the other hand they should avoid supplements with beta-carotene.

Keywords: Key words: reactive oxygen species, oxidative stress, antioxidant defense, dietary antioxidants, radical theory of ageing, caloric restriction.

Published: March 1, 2009  Show citation