Bad medicine: food intolerance

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“Do you believe that non-coeliac gluten sensitivity exists?” In a recent poll on bmj.com, 66% of the 941 well educated respondents said that they did—despite the lack of objective scientific evidence.1 2 Many doctors themselves have a gluten-free diet for many reasons, such as heart, bowel, and joint problems; migraine; or just to be generally “healthier.” Modern medicine has a thick veneer of science and evidence, but underneath it is really just opinion⇑.

Non-coeliac gluten sensitivity is just one of many “food intolerances.” Allergy UK, a charity sponsored by the food industry, claims that “45% of people” have a food intolerance. Doctors are berated for their lack of knowledge, and there is pressure for more allergy specialists. In the charity’s emotive Stolen Lives report,3 these intolerance are said to cause aches and pains, rashes, lethargy and anxiety, headaches, runny noses, and much more. But these symptoms are common medically unexplained symptoms, nebulous, and present in conditions like fibromyalgia and chronic fatigue syndrome. Much of “the science” of food intolerances is driven by reported increases in IgG concentrations with certain foods. These IgG concentrations are common in asymptomatic populations, have not been shown to be causally associated with symptoms in controlled studies, and are considered clinically “irrelevant” in guidelines.4 But this hasn’t stopped the allergy industry’s drive for profit. The “Yorktest” website, for example, offers celebrity endorsement, with cameos from well known television doctors, and a range of allergy testing that costs up to £299 (€356; $474).5

Then there are the interests of big food corporations. Almost a fifth of the US population buys gluten-free products. Annual growth in these products is 28%, and it is estimated that the market will be worth $6.6bn by 2017.6 Wheat-free or gluten-free products are twice the price, and presumably twice as profitable.7 Industry awards for “free from” foods, sponsored by supermarket and food producers, legitimise this new business bonanza as good for health.8

The number of patients who believe that food intolerance causes their symptoms is constantly increasing. Doctors are pressurised to test and treat—the prescription of gluten-free and wheat-free products has tripled over the past decade.9 10 Modern parents restrict children’s diets in a belief that they have allergies—limiting milk, eggs, fruit, corn, peanuts, fish, soya, and the rest. Perhaps there is no harm in this food anxiety culture. But where will this dubious “free from” food fad lead? Food intolerance is being driven by profit and market forces, not medical forces, and this is always bad medicine.