York researchers who pioneered a new diet test which they believe could improve the health of millions of people suffering from chronic illness are to collaborate with York University in a full-scale clinical trial.

John Graham of the privately-run York Nutritional Laboratory says simple changes to the diet of sufferers could save the NHS millions of pounds in drugs and dramatically improve the health of patients.

A mini-survey of 463 patients treated using the laboratory's test, launched 11 months ago, revealed that almost three quarters said their health had improved within 60 days.

Now Mr Graham hopes the full- scale trial, to be launched with professor Trevor Sheldon of York University's Social Sciences Research Institute, will give the laboratory's test full scientific credibility.

He said that could help persuade more doctors to refer patients suffering from chronic illness such as migraine, asthma, skin rashes and arthritis for tests.

Then simply altering their diet to avoid foods they were intolerant to could lead to dramatic improvements in their health - saving the NHS millions in drugs bills and improving the quality of their lives at a stroke.

The nutritional laboratory's latest test uses a pin-prick sample of a patient's blood, diluted and tested with samples of up to 93 common foods.

That enables the laboratory to advise patients which foods to cut out of their diets. The most common foods causing problems, Mr Graham says, are cow's milk, tomatoes, prawns, olives and cheeses.

But he said convincing doctors the method worked was difficult.

He said: "The science has to be completely proved. We want to carry out a full clinical trial within the UK."

Professor Sheldon confirmed the university was applying to the NHS Research and Development programme for funding to run a trial.

He said: "Their results are very encouraging, but it has not been proved yet. If the results do stand up, there could be real benefits, in terms of savings on drugs bills, outpatients visits, visits to GPs and, of course, people's health."

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