The scientists investigated the benefits of antioxidant use in preventing or curing illness and came to the conclusion that ingesting these substances has no benefits. They prove beneficial only in cases where there is an established vitamin deficiency.

Professor Ghezzi explains, 'Many people assume that taking antioxidants is good for them. Our research shows that this is only the case when an individual has been diagnosed with an obvious vitamin deficiency'.

No study to date has ever shown any benefits from antioxidants. On the contrary, some antioxidants are even harmful. This is because when antioxidants are ingested, the oxygen molecules affect not only disease but also the body's immune system and ability to synthesise certain hormones; these effects may be harmful and have negative consequences that outweigh the good.

'Nevertheless', says Professor Schmidt, 'oxidative stress can be valuable in treating disease under certain conditions. But that would entail the use of traditional medicines rather than antioxidants to treat the illness, since they attack only the sources of the oxygen molecules that are causing the disease in question, while leaving sources of healthy oxygen molecules unaffected'.

Our bodies need oxygen. Yet that same oxygen can also be the cause of oxidative stress and disease. Oxidative stress is a metabolic condition in which a greater number of reactive oxygen bonds are released than usual. It may be the result of factors such as excessive alcohol consumption, smoking, medicine use, physical or psychological stress, prolonged sun exposure, air pollution, intensive exercise or being overweight. To compensate for the effect, many people take antioxidants as a dietary supplement.

The study findings have been published in the British Journal of Pharmacology.