^ Biesiekierski JR (2017). "What is gluten?". J Gastroenterol Hepatol (Review). 32 Suppl 1: 78–81. doi:10.1111/jgh.13703. PMID 28244676. Similar proteins to the gliadin found in wheat exist as secalin in rye, hordein in barley, and avenins in oats and are collectively referred to as “gluten.” Derivatives of these grains such as triticale and malt and other ancient wheat varieties such as spelt and kamut also contain gluten. The gluten found in all of these grains has been identified as the component capable of triggering the immune-mediated disorder, coeliac disease.
^ Volta U, Caio G, De Giorgio R, Henriksen C, Skodje G, Lundin KE (Jun 2015). "Non-celiac gluten sensitivity: a work-in-progress entity in the spectrum of wheat-related disorders". Best Pract Res Clin Gastroenterol. 29 (3): 477–91. doi:10.1016/j.bpg.2015.04.006. PMID 26060112. A recently proposed approach to NCGS diagnosis is an objective improvement of gastrointestinal symptoms and extra-intestinal manifestations assessed through a rating scale before and after GFD. Although a standardized symptom rating scale is not yet applied worldwide, a recent study indicated that a decrease of the global symptom score higher than 50% after GFD can be regarded as confirmatory of NCGS (Table 1) . (…) After the confirmation of NCGS diagnosis, according to the previously mentioned work-up, patients are advized to start with a GFD .