In 1956, Denham Harman proposed the theory of ‘oxidative stress‘; in which he claimed that ageing is caused by a build-up of molecular damage to cells, from the actions of reactive forms of oxygen such as superoxide.

These free radicals (oxygen molecules with an imbalance of protons to electrons) are created as by-products of cells metabolising sugars to release energy – So, the Diet and Beauty industry claims that Antioxidants such as vitamins C and E supposedly work to mop these up, thus minimising potential cell damage.

The oxidative stress theory has dominated the field of ageing research ever since it was proposed, but now, a recent study published in the journal Genes and Development, suggests that the idea is probably incorrect and that superoxide is not a major cause of ageing.

David Gems, of University College London, and colleagues at the Institute of Healthy Ageing studied the action of key genes involved in removing superoxide from the bodies of the nematode worm Caenorhabditis elegans, a commonly used organism in research into ageing. By manipulating the worm’s genes, they were able to control the nematode’s ability to ‘mop up’ surplus superoxide and limit potential damage caused by free radicals. This modification should have given the GM nematodes an advantage over normal nematodes, in terms of ageing and lifespan.

However, contrary to the results predicted by the free radical theory of ageing, the researchers found that the lifespan of the worms was relatively unaffected by their ability to tackle the surplus superoxide. So, these findings, combined with similar recent findings from the University of Texas, using mice, suggest that the oxidative stress theory is incorrect.

Dr Gems, who led the study, noted that molecular damage was probably caused by numerous different chemicals within the cell, and went on to say:

Our results spectacularly failed to support the view of the free radical theory.

The fact is that we don’t understand much about the fundamental mechanisms of ageing – the free radical theory has filled a knowledge vacuum for over 50 years now, but it doesn’t stand up to the evidence.

A healthy, balanced diet is very important for reducing the risk of developing many diseases associated with old age, such as cancer, diabetes and osteoporosis, but there is no clear evidence that dietary antioxidants can slow or prevent ageing. There is even less evidence to support the claims of most anti-ageing products.

Dr Alan Schafer, Head of Molecular and Physiological Sciences at the Wellcome Trust, who funded the research, said:

With increasing lifespan comes greater exposure and vulnerability to the ageing process. Research such as this points to how much we have to learn about ageing and the importance of understanding the mechanisms behind this process.

This new study will encourage researchers to explore new avenues in ageing research.

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Posted by Jonathan in Biochemistry, Biology

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