Radical threat to body tissue

No expensive face cream is complete these days without the promise of an agent to wage war on oxygen free radicals.

Now scientists are suggesting that the ravages of these cellular troublemakers run deeper than wrinkles, and may be linked to common disorders of old age such as muscular degeneration.

In their chilling propaganda, cosmetic companies describe free radicals as treacherous cell matter that passes its time hacking at the delicate connective tissue that holds the skin together. In so doing it reduces the face to a battleground of premature wrinkles.

But while there is little evidence to support the industry's claims of jarred antioxidant remedies, a growing chorus of scientists are convinced that the scare-mongering may for once be well founded.

Malcolm Jackson, professor in the department of medicine at Liverpool University, is dedicated to studying the activity of free radicals in muscle tissue. He concludes that these unstable particles are probably released during sustained exercise training and in competition, and may spell disaster for anyone engaged in strenuous sport.

"The way we use the muscle is the key to the prevalence of free radicals - exhaustive exercise causes them to increase and they are likely to be released into the body and may have effects on other tissues," he said.

The familiar phenomenon of muscle pain after unaccustomed or excessive exercise is almost certainly associated with structural damage to the tissue, but it is only recently that these changes have been linked to the appearance of biochemical markers of muscle damage.

Professor Jackson said: "If these (biochemical markers) can be demonstrated to be caused by free radicals, there would be big implications for the prevention of muscle damage during training regimes in athletes and for the prevention of muscle pain and damage in people who are usually sedentary, undertaking unaccustomed exercise."

He added: "This raises the question of whether exercise is truly beneficial or not. Definitely in the short term it has important cardio-vascular benefits but potentially it may also have deleterious effects."

A free radical is defined as a particle capable of independent existence that contains one or more unpaired electron. The unpaired electrons confer a charge on the particle, making it highly reactive and capable of damaging a multitude of biological substances.

Free radicals are formed as a by-product of normal metabolism, but a muscle's unique ability to undertake very rapid and coordinated changes in energy supply renders it particularly susceptible to free radical damage.

These changes require major variations in the oxygen flux through the tissue and a corresponding electron flux through the intra-cellular chain reaction that releases energy, which in turn may predispose to the formation of oxygen-centred free radicals.

Researchers in Professor Jackson's unit have earmarked Vitamin E as a promising scavenger of free radicals, though its protective properties remain a mystery.