Antioxidants and Ageing -

Role of Antioxidants

It is now well established that there is a positive correlation between diet and length of life. In many animal species, lifespan can be increased up to 50% by suitable modification of the diet. Whether this enhancement is due to a reduction in free radical action, so that bodily antioxidants can more readily cope, remains to be seen. There is evidence that rats on low calorie diets suffer less free radical damage to their body proteins than those on unrestricted diets. This may be because they have larger quantities of the important enzymes that protect against free radicals . But antioxidants are unlikely to be the whole story, for in rats living longer on restricted diets there is known to be increased expression of certain genes in liver tissue. So genetic factors are also probably involved.

There is, however, some more direct evidence of increased free radical action with age. Scientists at the University of Kentucky have been studying the performance of gerbils in running mazes. Old gerbils, on average, make twice as many mistakes as young gerbils. But if old gerbils are given the free radical trapping antioxidant, butyl alpha phenylnitrone (PBN) for two weeks, their performance improves so as to be very bit as good as that of young gerbils. When the PBN is stopped, they go back to making as many mistakes as before.

The researcher, Thomas Johnson, of the University of Colorado has been able to breed a strain a roundworm with a lifespan more than twice that of others of the same species. The remarkable thing about these long living worms is that they have significantly higher levels of the enzymes super oxide dismutase and catalase than their less fortunate friends. These enzymes are natural antioxidants and are exactly the same as those that protects humans against free radicals.

It is, of course, arguable whether one can safely supply to humans results that have been obtained on little white furry rodents and roundworms. But the findings in these animal experiments do make it clear that, in a range of living creatures, there is an important link between antioxidants and ageing.

Here is another piece of strongly suggestive evidence. Proteins that have been damaged by free radical oxidation can be detected by highly sensitive tests for particular bits of protein components (amino acids) that are released in the course of the damage. Post-mortem examinations on human brains shows that old people have more of these bits in their brains than do young people. The inference is that natural antioxidants are not working as well in older people as they do in the young. If this is so, there is a strong probability that supplementary antioxidant vitamins can make up for the age-related deficiencies of the natural antioxidants that mop up free radicals in younger people.