Cut the risk of Cataract -

Cataract and Free Radicals

The mechanisms of the development of age related cataract are still a matter of argument, but it is becoming increasingly obvious that oxidation of the lens protein is an important factor. The fine protein fibres of which the internal lenses are made are themselves transparent. The transparency of the lens as a whole depends on the uniformity of diameter of these fibres and the evenness and parallelism with which they are laid down in the lens. When protein is damaged, this uniformity of structure is lost, and the fibres, instead of transmitting light evenly, cause it to be scattered and even reflected. The result is severely defective vision.

The view that age-related cataract may be due to free radical damage is indirect but very strong and is based largely on the differences between the levels of antioxidants in the bodies of people with cataract compared with those in comparable people with clear lenses. These trials have been reported in various respectable medical and scientific journals such as the British Medical Journal, Archives of Ophthalmology, Annals of the New York Academy of Science, and the American Journal of Clinical Nutrition.

One of the most impressive studies was carried out in the Department of Biomedical Sciences, University of Tampere, Finland, and published in the British Medical Journal in December 1992. in this project, 47 people with cataract and a carefully selected comparable group of 94 people with clear lenses were compared. The normal 'controls' were selected to be as similar as possible to those with cataracts in terms of age, sex, occupation, smoking history, blood cholesterol levels, body weight, blood pressure and the presence or absence of diabetes. All had blood samples taken that were analysed by highly sensitive method for levels of vitamin E and beta carotene. Beta carotene is the orange pigment in carrots and other vegetables that is converted in the liver to vitamin A.

The results showed that there was a significant relationship between the levels of vitamin E and beta carotene and the likelihood of having cataract. Low blood levels of these antioxidant vitamins were founding the cataract group; higher levels in the clear lens controls. People low in both vitamins were two and a half times as likely to have cataracts as those with higher levels. The authors of the study concluded: Low serum concentrations of the antioxidant vitamins alpha to copherol ( vitamin E) and beta carotene are risk factors for end stage senile cataract. Controlled trails of the role of antioxidant vitamins in cataract prevention are therefore warranted.

Another study, carried out in Canada and reported at an international conference, involved 175 cataract patients and the same number of people with clear lenses. Again, this study showed a meaningful difference in the intake of vitamins E and C in the two groups. Those who had taken extra C and E vitamins for five years or more were significantly more numerous in the clear lens group than in the cataract group. The epidemiologist, Professor James Robertson, head of the project, said, 'Supplementary vitamins C and E are associated with a significant reduction in risk of cataracts.'