Food intolerance: sifting the facts from the fantasies

Just how common is wheat allergy?

Last year, a two page feature article in the Express newspaper carried the headline, “Are you allergic to bread?” The thrust of the article was that one in three people has an intolerance to wheat which causes anything from bloating to depression. Unfortunately, the headline was both alarmist and misleading. More unfortunately still, the article contained several scientifically meaningless statements, contradictions, and factual errors. There were statements suggesting that fermentation of foods in the gut is similar to “low grade poisoning,” and wheat is “very hard for our bodies to digest.”

The suggestion that wheat intolerance affects 35% of the population was a gross overestimate, and no scientific studies have shown the incidence to be anywhere near this high. The current estimate, based on a study conducted by the then Ministry of Agriculture, Fisheries, and Food for the total prevalence of all food allergies (including peanuts) in the United Kingdom is 1.4% of the adult population.1 Coeliac disease is the main form of wheat intolerance and is characterised by a specific physiological pathology whereby a T cell mediated delayed hypersensitivity is triggered by consumption of the wheat protein, gluten. Coeliac disease is estimated to have an underlying prevalence--that is, diagnosed plus undiagnosed cases--of 0.3%.2

Techniques have improved

The highly sensitive techniques now available mean that it is possible to identify people with coeliac disease that had previously been undiagnosed because the symptoms were relatively mild. To the casual observer, this might be taken as an indication that the prevalence of coeliac disease is increasing. However, the reality is that a proportion of cases, such as those with mild symptoms, had simply not been picked up. Symptoms of coeliac disease classically include diarrhoea, weight loss, and malnutrition, but not the symptoms mentioned in the article, …