Wheat starch, gliadin, and the gluten-free diet

Individuals with celiac disease generally are advised to follow a lifelong gluten-free diet and avoid consumption of the prolamins gliadin (wheat), secalin (rye), and hordein (barley). Although the designation of the diet as glutenfree may imply that the diet contains zero gluten, this is not necessarily true. In some countries (eg, United States, Canada), the gluten-free diet is completely devoid of gluten and is based on foods such as rice and corn that are naturally gluten free. In others (eg, Scandinavia, United Kingdom), the gluten-free diet may include foods such as wheat starch that have been rendered gluten free but nonetheless contain small amounts of toxic prolamins. The discrepancy in the use of foods rendered gluten free exists because the amount of toxic prolamins that individuals with celiac disease may consume without damaging the mucosa of the small intestine is unknown. Minimal research has been conducted on the toxicity of foods rendered gluten free, and there are no definitive data about whether the small amount of prolamin found in these products is safe to consume. Nonetheless, the Codex Alimentarius Standard for gluten-free foods allows a certain amount of prolamin in foods designated gluten free, and these products have been used in many countries for several decades. Well-designed, scientifically sound studies are needed to help determine the amount of toxic prolamins, if any, that may be safely consumed by individuals with celiac disease. Until this research is conducted, dietitians in the United States should continue to advise their patients against the use of wheat starch and other foods rendered gluten free.