Non-celiac gluten hypersensitivity lacks validated diagnostic biomarkers, and current diagnostic criteria rely on exclusion of celiac disease and wheat allergy followed by gluten challenge, which limits diagnostic accuracy and population prevalence estimates.

When someone eats gluten, parts of it survive digestion and trigger an immune response in the gut. This response damages the lining of the intestine and changes the balance of gut bacteria. Because these changes are not unique or measurable with a blood test or scan, doctors can only tell if someone has this condition by removing gluten and seeing if symptoms improve, then adding it back to see if they return.