Previous studies have suggested that the degenerative brain disorder may in some way be linked to cell damage caused by oxidation, the process by which oxygen is converted into energy.

Vitamins E and C and the carotenoids are known to help minimise this effect by mopping up free radicals, the particles released by oxidation which cause damage.

Researchers from three US centres tested whether the use of these so-called anti-oxidants could have any positive impact on the development of Parkinson's.

They could find no positive effect from taking dietary supplements, but their work does suggest that upping the amount of vitamin E in the diet may have some protective effect.

Long-term study

Sources of vitamin E

Wheat germ Nuts Green leafy vegetables

The researchers, from Harvard School of Public Health, Brigham and Women's Hospital, and Harvard Medical School, examined data on 76,890 women and 47,331 men.

The data was collected on the women since 1984 and on the men since 1986.

By 1998 161 of the women and 210 of the men had been recorded as developing Parkinson's symptoms.

Lead researcher Dr Shumin Zhang said: "In these two large cohorts, we found no evidence that use of vitamin E or C supplements or multivitamins reduced the risk of Parkinson's.

"In contrast, however, higher intake of dietary vitamin E was associated with a significantly lower risk of Parkinson's."

Dr Zhang said it was possible that the people who took part in the study were not representative of the population as a whole.

He also admitted that other dietary or lifestyle factors may be responsible.

Protective effect

Professor Leslie Findley, medical adviser to the European Parkinson's Disease Association, told BBC News Online there was no firm evidence that vitamin E - or any other dietary component - played a role in helping to protect the brain cells.

However, he said there was research to suggest that a lack of vitamin E may be implicated in a condition called cerebellar ataxia in which shrinkage of the brain leads to Parkinson's-type symptoms such as lack of limb control and coordination.

He said: "Drugs that protect the neuron (brain cell) in Parkinson's disease is what everybody is looking for.

"As far as I am concerned the major finding here is that supplements do not make any difference."

Professor Findley said it was sensible for Parkinson's patients to eat a healthy diet and to refrain from smoking.

The research is published in Neurology, the scientific journal of the American Academy of Neurology.