Non-Celiac Gluten Sensitivity (NCGS) is a syndrome characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected by either celiac disease (CD) or wheat allergy (WA). Although NCGS is triggered by gluten-containing cereals, the offending dietary protein has not been identified yet, and could include other components such as amylase-trypsin inhibitors (ATIs). Indirect evidence suggests that NCGS is more common than CD. Using a self-administered evaluation incorporating a modified Gastrointestinal Symptom Rating Scale, the patient identifies 1 to 3 main symptoms that are quantitatively assessed using a Numerical Rating Scale ranging from 1 to 10. The double-blind placebo-controlled gluten challenge (8 g/day) includes a one-week challenge followed by a one-week washout of strict gluten free diet (GFD) and by the crossover to the second one-week challenge. The vehicle should contain cooked, homogeneously distributed gluten. A variation of 30% of 1 to 3 main symptoms between the gluten and the placebo challenge should be detected to discriminate a positive from a negative result. Note that NCGS may be transient, therefor gluten tolerance needs to be re-assessed in patients with NCGS.
Carlo Catassi, et al. Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts’ Criteria. Nutrients. 2015 June; 7(6): 4966-4977.