Cataracts, clouding of the eye lens, are the principal cause of blindness and visual impairment in the world. They are particularly common among the elderly. New research suggests that the anti-oxidant vitamins C and E may be effective in preventing the developments of cataracts.
The eye lens is continually exposed to light and oxygen. As light is absorbed, it generates an active form of oxygen, oxyradicals. Normally, the body’s enzyme defence system, which involves the anti-oxidant vitamins C and E, protects against the effects of these oxyradicals. However, if for some reason the defence mechanism breaks down and they remain unchecked, the oxyradicals appear to interfere with the normal elimination of damaged proteins from the lens. This can lead to oxidative damage and the development of cataracts.
Studies have shown that vitamins C and E can protect against light-induced cataracts by preventing or slowing down this damage process. People who have higher intakes or blood concentrations of these vitamins have a reduced risk of developing cataracts whereas those with low levels of vitamins C and E are at increased risk of developing the condition.
In the USA, almost 18,000 men took part in a study to examine the effects of vitamin supplementation on the risk of developing cataracts. All were free of cataracts at the start of the study. The group of men who regularly took a multivitamin or who took a multivitamin plus vitamin E and/or C were found to have a 25% lower risk of developing cataracts. In those who had used a multivitamin supplement for more than ten years the risk was reduced further to 32%. The protective effects of multivitamins were even more dramatic among past and current cigarette smokers, whose risk of developing cataracts was reduced by 50% and 60% respectively.