Although medical diagnoses of adverse reactions to certain foods are on the irse, the truth is that many people believe in intolerances that do not exist.
It is the scourge of birthday parties and affects an increasing number of children, but could peanut allergy soon be a thing of the past? In early trials, doctors at Addenbrooke's Hospital in Cambridge, UK, claim to have successfully treated 20 children suffering from severe peanut allergies - symptoms of which include potentially dangerous swelling of the airways, breathing problems and asthma - by "retraining" their faulty immune systems. After six months of taking controlled doses of peanut flour, some of the youngsters could eat up to 12 of the nuts a day without experiencing any life-threatening allergic reaction.
Although it is not being billed as a cure, experts hope that the discovery will not only ease the lives of many affected children in the future, but also enable parents who are over-sensitive to the concept of food allergies to relax. For although allergies and intolerances are on the rise among children, there are far more parents who erroneously believe their child needs to avoid certain foods. It is generally accepted that six to eight per cent of children suffer from a food allergy (that figure drops to three per cent in adulthood), yet more than one fifth of parents believe their child to be allergic to peanuts, dairy, wheat or shellfish. The result, say some, is a burgeoning paranoia about food allergies that can have a negative impact on a child's life.
"A real food allergy can be serious and have severe implications," says Catherine Collins, the chief dietician at St George's Hospital in London and a spokeswoman for the British Dietetic Association. "But there is a lot of hype surrounding intolerances and allergies and commercial companies make a lot of money from tests like hair analysis and inaccurate blood analysis that wrongly claim to diagnose them. The result is that children not only become anxious about food, but that they sometimes cut out entire food groups because their parents believe them to be problematic."
Collins says she has come across children who are eating far too few dairy foods to support their growth because parents think they are lactose intolerant. "There is so much confusion about what an allergy is," she says. "And the power of persuasion plays a huge part in people thinking that their child has one." A true allergy occurs when the immune system responds to an offending food by producing large quantities of immunoglobulin E. It can be fatal, with symptoms including swollen lips, an itchy throat, nausea and anaphylaxis. Food intolerances are more common, but less easily diagnosed. There are no confirmed figures, but up to one fifth of people suffer at some time or another, according to the charity Allergy UK. What marks intolerances apart from allergies is that they are not life-threatening and often require no form of dietary manipulation. Indeed, many of the symptoms often associated with an intolerance such as headaches, bloating and nausea occur hours after a food has been eaten and can usually be attributed to something else.
Collins says that the accepted way to treat an intolerance is to build up a resistance by gradually eating more of the offending item: "An intolerance is different to an allergy and exposure to tiny amounts of a food will help to lessen the risk more than avoiding it altogether. Even people with a severe lactose (milk sugar) intolerance can tolerate 6g of lactose a day." She strongly advises against any commercially available tests that claim to diagnose or treat an intolerance. "They are not only a waste of money, but are often very inaccurate," Collins says. "They cause more anxiety than they are worth."
It is because of inaccuracies in testing that misdiagnoses of allergies and intolerances have soared in recent years and that, consequently, parents have become more paranoid. A recent study in Denver looked at 125 children with an average age of four who had been diagnosed with a total of 60 food allergies between them, although none by medical professionals. Dr David Fleischer, a paediatric allergist who led the research, presented each of the children with carefully controlled "food challenges" in which, much like the peanut approach, they were fed minute amounts of the food that was considered to be the problem. By the end of the study, 90 per cent of the allergies turned up negative. "In our department we see people who have undergone commercial tests and are avoiding up to 30 foods as a result," Fleischer says. "It transforms their life when we confirm that, actually, their allergy doesn't exist."
Not that persuading people they have an imaginary allergy is always easy. Psychologists at the University of California in Irvine were studying false memories when they discovered that perceived problems with food can easily be manipulated. The researchers asked 336 subjects to complete a survey about their early eating memories. A week later they were each handed a bogus dietary profile which contained a single untruthful fact about the history of their relationship with food. Some were told that they had become sick when eating pickles or hard-boiled eggs. Around 40 per cent of people said they clearly remembered having an adverse reaction to the food in question or believed their intolerance to be real. Compared with a control group, those who were fed the falsehood also said they would avoid the offending food whenever possible.
Further proof that people are increasingly phobic about food comes from psychologists at the University of Birmingham who interviewed 300 people with a supposed food intolerance and 600 people who considered themselves healthy. However, they found little convincing evidence to link food to any of the symptoms - which ranged from headaches and upset stomachs to hyperactivity - that the sufferers had complained about. Although the researchers acknowledged that real intolerances do exist, they said that most of those reported by their subjects "were based on pure fantasy".
One woman even thought that she was allergic to bananas because her mouth became numb when she ate banana-flavoured ice cream, but investigation found it was the coldness of the dessert and not its fruit content that was the problem. So how do experts explain the benefits reported by some people when they cut out a food only for their energy to be boosted or their abdominal bloating to be reduced? Collins says a placebo effect may be at play. "Sometimes people are so set on the idea that changing their diet will make them feel better that it does up to a point," she explains. "And if they were eating too much of something like wheat, which many people do, then reducing their intake probably will make them feel less lethargic. But to say they have an intolerance is completely inaccurate."