September 6, 2016

expert reaction to study looking at prevalence of coeliac disease and of people following a gluten-free diet in the US

Publishing in JAMA Internal Medicine a group of researchers have reported that the incidence of coeliac disease has not changed in recent years, but the number of people in the USA who follow a gluten-free diet has increased significantly.

Prof. Anthony Frew, Professor of Allergy & Respiratory Medicine, Royal Sussex County Hospital, said:

“This study is of interest and fits with our feeling within the allergy community that many people have put themselves on gluten-free diets without any clinical evidence of gluten sensitivity. The work itself is well done and provides pretty convincing evidence of a flat trend in coeliac disease in the US, so no increase in its incidence.

“The tendency to blame gluten for a variety of ailments has increased in recent years – there is absolutely no evidence that wheat-free diets are intrinsically ‘healthy’. There are some people who are not coeliac but are intolerant of wheat and get bloating, abdominal discomfort and variable bowel movements after eating wheat, which most doctors would label as irritable bowel syndrome (IBS). This is not a new phenomenon and relates to undigested wheat getting into the large bowel where it is fermented and produces gas which in turns causes bloating, wind etc.

“Health practitioners often recommend reducing the intake of wheat in IBS and symptoms often improve. This is not a food allergy but can be appropriately labelled as an intolerance. Complete avoidance of wheat is not usually necessary to relieve IBS symptoms, whereas in coeliac disease there is an immune reaction against wheat proteins (gluten). Patients with proven coeliac disease are entitled to gluten-free products on prescription but those with IBS are not. Many people with intolerance refer to themselves as being ‘allergic to wheat’. This is not technically correct: in medicine an allergy means you have an immune reaction against the offending product and IBS sufferers do not have an immune reaction to wheat.

“This study indicates that there is an increasing tendency for people to label themselves as gluten-sensitive, when they are not coeliac. It also suggests there is no upward or downward trend in the number of people who truly have got coeliac disease.”

Dr Ian Johnson, Nutrition researcher and Emeritus Fellow, Institute of Food Research, said:

“This small but rigorous study seems to confirm that, unsurprisingly perhaps, the rising popularity of gluten-free diets is not accounted for by any increase in clinically proven coeliac disease in the USA. The origins of the gluten-free movement remain mysterious, but at least it has led to a valuable increase in the range and availability of gluten-free products for those who do need them.”

Prof. Alastair Watson, Institute of Food Research, and Professor of Translational Medicine, UEA, said:

“In people who have coeliac disease, their symptoms are caused by eating wheat, barley or rye. These patients have characteristic changes to their immune system and to the lining of the bowel, and there are also genetic changes.

“This new research shows that the incidence of coeliac disease has not changed in recent years. However the number of people in the USA who have put themselves on a gluten-free diet has tripled over the last seven years.

“We know from previous research that there are some patients who don’t have coeliac disease but whose stomach and bowel symptoms can be improved when they go on a gluten-free diet, however it seems likely that the majority of people who put themselves on a gluten-free diet do so as a lifestyle choice. This new research shows how popular lifestyle gluten free diets have become.”

‘Time trends in the prevalence of celiac disease and gluten-free diet in the US population: results from the National Health and Nutrition Examination Surveys 2009-2014’ by Hyun-seok Kim et al. published in JAMA Internal Medicine on Tuesday 6 September 2016.

Declared interests

Dr Ian Johnson and Prof. Alastair Watson declare that they have no interests to declare.

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