FROM:
Aust N Z J Ophthalmol 1995 (Feb); 23 (1): 3–7
Florence TM
Centre for Environmental and Health Science Pty Ltd,
Sydney, NSW
Evidence is accumulating that most of the degenerative
diseases that afflict humanity have their origin in
deleterious free radical reactions. These diseases include
atherosclerosis, cancer, inflammatory joint disease, asthma,
diabetes, senile dementia and degenerative eye disease. The
process of biological ageing might also have a free radical
basis. Most free radical damage to cells involves oxygen
free radicals or, more generally, activated oxygen species
(AOS) which include non–radical species such as singlet
oxygen and hydrogen peroxide as well as free radicals. The
AOS can damage genetic material, cause lipid peroxidation in
cell membranes, and inactivate membrane–bound enzymes.
Humans are well endowed with antioxidant defences against
AOS; these antioxidants, or free radical scavengers, include
ascorbic acid (vitamin C), alpha–tocopherol (vitamin E),
beta–carotene, coenzyme Q10, enzymes such as catalase and
superoxide dismutase, and trace elements including selenium
and zinc. The eye is an organ with intense AOS activity, and
it requires high levels of antioxidants to protect its
unsaturated fatty acids. The human species is not
genetically adapted to survive past middle age, and it
appears that antioxidant supplementation of our diet is
needed to ensure a more healthy elderly
population.