A protein composite that appears in foods processed from wheat and related species, including barley and rye. Adhering to a gluten-free diet has become a common practice to alleviate the symptoms of autism, although there is debate about the effectiveness of this approach. Casein-free diets are also popular. Casein is a protein found in milk and milk products. A gluten-free and casein-free diet is commonly referred to as a GFCF diet.