Antioxidants 'cannot slow ageing'

Diets and creams claiming their antioxidant properties could cheat ageing may be worthless, a study says.

Using Nematode worms, scientists found even those given enhanced antioxidant powers to deal with tissue damaging "free radicals" did not live longer.

The team from University College London said, in the Genes and Development journal, there was "no clear evidence" they could slow ageing.

Antioxidants are a staple of the beauty and health industries.

This has been based on a 50-year-old theory. The free radical theory has filled a knowledge vacuum for over 50 years now, but it doesn't stand up to the evidence

Dr David Gems
UCL

In 1956, it was suggested that ageing was caused by a build-up of molecular damage caused by reactive forms of oxygen, called superoxides or free radicals, circulating in the body. This is known as oxidative stress.

Antioxidants supposedly worked to mop up these free radicals, minimising their damage.

This week's study, however, could explain why many studies aimed at proving the theory have been inconclusive.

Nematode worms

The tiny Nematode worm, despite appearing to be far-removed from the human species, is a useful tool for scientists who want to explore how our bodies work.

They share many genes with humans, and, crucially, have a lifespan measured in days, which allows scientists to get clues about long-term changes.

The UCL team, led by Dr David Gems, genetically manipulated nematodes so that their bodies were able to "mop up" surplus free radicals.

This in theory, should give them an advantage over normal nematodes in terms of ageing and lifespan.

However, these worms lived just as long as the others, suggesting that "oxidative stress" is less of a factor in the ageing of our cells and tissues as some have suggested.

Dr Gems said: "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.

"It is clear that if superoxide is involved, it plays only a small part in the story - oxidative damage is clearly not a universal, major driver of the ageing process."

He said a healthy, balanced diet was important for reducing the risk of many "old age" diseases, such as cancer, diabetes and osteoporosis, but there was no clear evidence that eating antioxidants could slow or prevent ageing, and even less evidence to support the claims made by antioxidant pills and creams.

'No magic bullet'

The research was supported by the Wellcome Trust, and Dr Alan Schafer, its head of molecular and physiological sciences, said: "Research such as this points to how much we have to learn about ageing, and the importance of understanding the mechanisms behind this process."

A spokesman for the British Dietetic Association said that it had been hard to find the evidence to support antioxidants from previous studies.

She said: "All the evidence has come from epidemiological studies looking at the whole diet - where there was some sign of benefit to people who ate diets with antioxidants, but also who ate lots of other good things.

"What this shows is that there is likely to be no one 'magic bullet' in terms of diet and health -the important thing is still achieving a healthy balance."

A spokesman for the Cosmetic Toiletry and Perfumery Association said cosmetic companies carry out extensive research and rigorous scientific studies to ensure claims are supported by robust evidence.

"Findings on the genetics of a particular nematode worm may not be directly relevant to the complex process of ageing as it happens in higher animals such as the human," the association added.

Source: http://news.bbc.co.uk/2/hi/health/7754644.stm, 01 Dec 2008