By Allergen Bureau

What Causes Non-Coeliac Gluten Sensitivity?  

While 1-2 per cent of the Australian population has been diagnosed with coeliac disease or wheat allergy, around 10 per cent report having non-coeliac gluten sensitivity, a condition that remains controversial due to the lack of scientific understanding of the biological mechanisms and available diagnostic tests.  

Diagnosis of non-coeliac gluten sensitivity currently relies on a double-blind challenge test where people consume foods that either contain gluten or are gluten-free, without knowing which they have been given. A strong ‘nocebo effect’ has been observed with these tests, where people experience symptoms even when consuming the placebos.  

A new study published in The Lancet has aimed to shed light on this nocebo effect. Participants with self-reported non-coeliac gluten sensitivity unknowingly received either gluten or gluten-free meals, with correct or incorrect prior information about the meal’s contents. Interestingly, symptoms only differed among those expecting gluten (regardless of whether or not their meal contained gluten), suggesting expectation plays a major role in non-coeliac gluten sensitivity symptoms.  

Overlapping conditions like functional dyspepsia and irritable bowel syndrome were common among participants. Considering these findings, clinical management of non-coeliac gluten sensitivity should utilise a multidisciplinary team, including gastroenterologists, psychologists, and dietitians, while potentially moving beyond the gluten-free diet to avoid deficiencies in vitamins, nutrients, and fibre that are often associated with this eating pattern.   

Further research is needed to understand the role of the gut-brain axis in non-coeliac gluten sensitivity.  

Reference: de Graaf, M. et al. (2024), The effect of expectancy versus actual gluten intake on gastrointestinal and extra-intestinal symptoms in non-coeliac gluten sensitivity: a randomised, double-blind, placebo-controlled, international, multicentre study. The Lancet. DOI: 10.1016/S2468-1253(23)00317-5. See also the accompanying editorial.