Millions falsely believe they have food allergies

Britain's status as a nation of hypochondriacs was confirmed yesterday by a survey showing that while more than 30 per cent of people believe they have a food allergy, fewer than 2 per cent genuinely do.

The epidemic of heightened psychological sensitivity to foods is revealed in the survey by Datamonitor, a market research agency. The agency blames the rise on "inaccurate self-diagnosis" and a confusion between food allergy and food intolerance.

A genuine food allergy is caused by an immunological response to a food, which may cause a skin rash or diarrhoea. In extreme cases, an allergy can induce anaphylactic shock, the life-threatening reaction that requires emergency treatment with adrenaline.

Food intolerance may be triggered by chemicals in food. However, it is more likely to be a psychological response that has resulted from an associa- tion between a food and a bout of illness.

Tom Sanders, Professor of Human Nutrition at King's College London, said: "Psychological food intolerance involves people who believe that when they eat a food it has an adverse effect. But when you challenge them with the same food fed through a tube [so they are unaware of what they are eating], it has no effect."

Food allergies were becoming more common, even though most of those who thought they had one were misled, he said. A survey of children on the Isle of Wight found that, at most, 2 per cent were allergic to peanuts or shellfish.

One of the fastest-growing allergies is to wheat, which causes bloating and weight loss and affects one person in 300. "People are getting more severe food allergies than in the past," Professor Sanders said. "I have a student who has to carry an adrenaline 'pen' [for giving emergency injections] around with her because she is allergic to peanuts."

Most adverse reactions to foods are to natural products, not to synthetic additives such as colourings and flavour enhancers. Yet the latter are the products that cause most public concern. "The less people have got to worry about, the more they worry about things in their food," Professor Sanders said.

A study by the Government Food Standards Agency in 2000 concluded that food allergies affected between 1.4 and 1.8 per cent of the population – the equivalent of 80,000 to 100,000 people. In children the rate was put at 8 per cent.

The commonest foods that cause a reaction in children are cow's milk, eggs, wheat, nuts and soya, which account for 90 per cent of cases. In adults the commonest foods are nuts, fish and shellfish.

The Datamonitor report says that up to 30 per cent of allergic reactions occurred after the individual had eaten what appeared to be a safe food that was wrongly or inadequately labelled. More sensitive testing for ingredients – reactions can be provoked by one-thousandth of a peanut – and stronger enforcement of labelling laws were required, it said.

Many adults were cutting foods from their diet because they suspected they were allergic to them without evidence and parents were denying certain foods to their children, despite most growing out of their allergies, the report said. "The trend to self-diagnosis is worrying because it means that by eliminating certain food-types up to one-third of people are unnecessarily depriving themselves of nutritious food."