Coeliac disease disease genotypes. It is suspected that some of them may have been beneficial by providing protection against bacterial infections. The majority of the proteins in food responsible for the immune reaction in coeliac disease are the prolamins. These are storage proteins rich in proline ("prol-") and glutamine ("-amin") that dissolve in alcohols and are resistant to proteases and peptidases of the gut. Prolamins are found in cereal grains with different grains having different but related prolamins: wheat (gliadin), barley (hordein), rye (secalin) and oats (avenin). One region of α-gliadin stimulates membrane cells, enterocytes, of the intestine to allow larger molecules
Gluten conditions often practice gluten-free diets. The occurrence of oat avenin toxicity depends on the oat cultivar consumed, because the immunoreactivities of toxic prolamins are different among oat varieties. Also, many oat products are cross-contaminated with other gluten-containing cereals. Gluten is a protein complex that accounts for 75–85% of the total protein in bread wheat. In home or restaurant cooking, gluten is prepared from flour by kneading the flour under water, agglomerating the gluten into an elastic network known as a dough, and then washing out the starch. Starch granules disperse in low-temperature water, and the dispersed starch is sedimented and