One in four has an allergic disease

The Allergy Research Foundation (ARF) says there is now abundant evidence that conditions such as irritable bowel syndrome and asthma are linked to food allergies.

But the ARF says the connection is still not fully recognised by many GPs, with the result that many patients suffer years of misery before they are properly diagnosed.

An ARF conference on Tuesday will highlight new research that suggests the link between food intolerance and medical problems is very strong.

This includes work by Professor Joseph Egger, professor of neurology at the Children's Hospital, Munich, who has used brain mapping to show the changes that take place in children suffering from attention deficit disorder after they have eaten certain foods, such as milk, chocolate and cereals.

It is estimated that one in four people suffers from some form of allergic disease, whether it be a food or environmental sensitivity.

Childhood disease

Food intolerance is believed to cause or exacerbate such conditions as asthma, migraine, nasal congestion, eczema, hyperactivity, irritable bowel syndrome and Crohn's disease.

One in 10 children has eczema and an estimated one in seven has asthma but exactly how many cases are linked to food is not known.

Between 6% and 10% of children under the age of three will have symptoms associated with food - probably milk. But most of those will disappear as they become older.

For the 22% of those with irritable bowel syndrome, the ARF believes a change in diet can help alleviate the problems in half of those cases.

And evidence shows that 50% of those suffering from Crohn's disease feel better when a particular food is eliminated from the diet.

Doctors are sceptical

However, many doctors are still resistant to the idea that medical conditions can be effectively managed by controlling diet, rather than by more traditional pharmaceutical methods.

Dr Michael Tettenborn, a consultant paediatrician at the Frimley Children's Centre in Surrey, has used diet management to tackle a range of problems in children, including attention deficit disorder, irritable bowel syndrome and migraine.

Milk has been linked to medical conditions

Dr Tettenborn says: "We are trying to get the message over to the medical profession that diet management is a useful tool to explore.

"There is great potential for managing patients with food intolerance through diet, rather than through costly medication."

Dr Tettenborn says many doctors had been turned against dietary management because some people had made excessive claims about its potential impact.

He says scepticism had been fuelled further by non-medical practitioners inventing tests of "very dubious validity" to prove the worth of the technique.

Another problem was that medical students were not taught about the subject during their training.

And drug companies were reluctant to research the benefits of diet management because they could not make money out of it.

'Re-education needed'

Professor Jonathan Brostoff, professor of allergy and environmental health, University College, London, said re-education of doctors was vital.

"The education system does not even mention nutrition, let alone food intolerance. We do not have a body of doctors who have learned about the role of food and diet in health," he says.

"The way we diagnose food intolerance is a bit 'suck it and see', and unfortunately the medical profession, which is very much clinical science-orientated, has made this sort of approach unacceptable."

The ARF is calling for the government to fund research into food intolerance and asking for charitable donations.