THE ROLE OF FREE-RADICALS IN DISEASE

Evidence is accumulating that most of the degenerative diseases that a fflict humanity have their origin in deleterious free radical reaction s. These diseases include atherosclerosis, cancer, inflammatory joint disease, asthma, diabetes, senile dementia and degenerative eye diseas e. The process of biological ageing might also have a free radical bas is. Most free radical damage to cells involves oxygen free radicals or , more generally, activated oxygen species (AOS) which include non-rad ical species such as singlet oxygen and hydrogen peroxide as well as f ree radicals. The AOS can damage genetic material, cause lipid peroxid ation in cell membranes, and inactivate membrane-bound enzymes. Humans are well endowed with antioxidant defences against AOS; these antioxi dants, or free radical scavengers, include ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), beta-carotene, coenzyme Q10, enzymes suc h as catalase and superoxide dismutase, and trace elements including s elenium and zinc. The eye is an organ with intense AOS activity, and i t requires high levels of antioxidants to protect its unsaturated fatt y acids. The human species is not genetically adapted to survive past middle age, and it appears that antioxidant supplementation of our die t is needed to ensure a more healthy elderly population.