Drs Elmer Cranton and James Frackelton describe them, in an article entitled 'Free Radical Pathology in Age Related Diseases' published in The Journal of Holistic Medicine (1984 6(1)) as follows: 'Every free radical has an unpaired electron in an outer orbit, causing it to be highly unstable and to react almost instantaneously with any substance in its vicinity. These reactions often cause a cascade of new free radicals in a multiplying (chain-reaction) effect.' It is such free radical activity which allows high level radiation to damage and kill, as the rays (gamma, X, ultraviolet, cosmic etc.) knock electrons out of orbiting pairs, thus producing free radicals.

Radiation is one extreme of the range of this phenomenon, although some scientists describe the damage free radicals cause to cells in everyday life as 'continuous internal radiation'. Surprisingly perhaps, a good deal of free radical activity is produced by the body itself for specific purposes (killing bacteria for example and in detoxification processes). This phenomenon can therefore be considered to be 'controlled internal radiation'. Oxygen in its everyday form is an amazing substance which can either generate free radicals or can help to switch them off. As Cranton and Frackelton explain it:

A liter of normal atmospheric air on a sunny day will contain over one billion hydroxyl free radicals, whereas oxygen at normal physiological concentrations in living tissues neutralizes more free radicals than it produces. When oxygen levels are reduced (low), as occurs in ischemic tissues (lacking good blood supply and therefore poorly oxygenated) oxygen becomes a net contributor of free radical damage.

Some oxygen processes are more likely to produce large quantities of free radicals than others, and it is when there is either too much or too little oxygen present in a metabolic reaction that the worst situations arise. Evolutionary processes have fortunately helped to ensure that we can survive in an oxygen environment through the provision of an army of substances which protect us, with healthy body cells producing and/or using over a dozen antioxidant control substances.

What free radicals do
If cellular damage is a cause of ageing, and if we can slow down that damage, it makes sense to think that ageing can be retarded. For example, when free radical activity is taking place, damage to cells occurs, protein synthesis becomes impaired, proteins become cross-linked and tangled, tissues become less pliable, arteries incur damage leading to atherosclerosis, genetic material (DNA/RNA) is damaged leading to possible cancer development and to inefficient repair processes, age pigments accumulate which literally drown the cells in lipofuscin, preventing them from functioning, and in general all the signs and indications of ageing are promoted, whether this is stiffness, poor circulation or wrinkles (cross-linkage), not to mention diseases such as atherosclerosis, arthritis, cancer and, it is now believed, Alzheimer's disease.