Seven divers took part in the trials

The scientists from Croatia and Norway gave vitamins C and E, which work as antioxidants, to divers, the Journal of Physiology reported.

The vitamins stopped ill-effects of the dive on the cells lining blood vessels, which can lead to high blood pressure and other associated diving problems.

But diving experts said the vitamins would have a limited impact.

The intervention showed a positive effect Ante Obad, lead researcher

The researchers, from the University of Split School of Medicine in Croatia and the Norwegian University of Science and Technology carried out the study on seven professional divers before a 30-minute, 30-metre dive.

They performed two dives 24 hours apart, with doses of vitamins C and E administered two hours before the second one.

Six of the divers took part in a second trial eight months later, in which some were given antioxidants while others received a dummy pill.

The team found that antioxidant treatment prevented endothelial dysfunction, which stops the cells lining blood vessels working properly, causing high blood pressure.

High blood pressure is relatively common in divers and can lead to conditions such as pulmonary oedema - fluid on the lungs which can be found in divers.

Decompression

It is thought endothelial dysfunction is caused by gas bubbles getting into the circulatory system during and after decompression from dives.

Lead researcher Ante Obad said: "The intervention showed a positive effect. Although generally safe, diving may be associated with serious, and sometimes fatal consequences, which are usually related to decompression sickness.

"This raises the possibility that pre-dive intake of antioxidant vitamins may prevent some of the negative effects of diving."

But a spokesman for the London Diving Chamber, which offers medical advice and treatment to divers, said the use of antioxidants such as vitamins C and E would have a limited effect.

"Antioxidants basically remove excess by-products form the blood system. But the impact on diving-related illnesses would be pretty insignificant.