SOD is an enzyme produced by the body and present in every cell. It is thought to play a major role in the protection of cells against oxidative damage and is also available as a nutritional supplement on some markets.
However a new theory put forward by a team of UK scientists suggests that the oxygen free radicals produced by white blood cells, said to be responsible for numerous diseases ranging from cancer to arthritis, may not in fact be responsible for causing disease.
Dr Tony Segal and colleagues wrote in the journal Nature earlier this year that "the basic theory underlying the toxicity of oxygen radicals is flawed".
The researchers said they had discovered that it is not free radicals that give white blood cells their destructive power, but enzymes which effectively digest foreign invaders. Production of these enzymes is triggered by the flow of the mineral potassium within the cell.
When the scientists blocked this process, the cells were unable to fight pathogens, showing that free radicals may not be toxic as thought.
The theory would not only have a major impact on research into SOD, thought to neutralize the free radical substance superoxide, but also on much of the nutraceutical industry, which has aimed to prevent disease by fighting the build-up of free radicals with antioxidants, such as vitamin C or E.
However Professor Joe McCord from the University of Colorado, credited with the co-discovery of SOD in 1969, which prompted an explosion in the study of the role of antioxidants, will take up the other side of the debate at a round table organized by the Societe Francaise des Antioxydants at its third conference on SOD next Friday.
Other research to be presented at the conference offers new evidence surrounding SOD's role in the ageing process. A study on Drosophila flies by John P. Phillips from the University of Guelph in Canada looks at SOD's ability to protect mitochondria and how this process may be linked to the benefits of dietary restriction on extending lifespan.
The conference, taking place at the Institut Pasteur in Paris, will also look at the bioavailability of SOD and its protection when passing through the stomach.
Two companies, Bionov and Ninapharm have recently developed SOD dietary supplements derived from watermelon, said to be the richest plant source of the enzyme. Prior to this, the enzyme was produced from red blood cells but this was stopped in 1992 because of fears of contamination with disease.