Home > Gastroenterology > What is Celiac Disease? Get the Flash Player to see this player. Rate: (Click the stars to rate) Published on Nov 16, 2010 by Cleveland Clinic, Views: 2427 Celiac disease is when the body doesn't tolerate gluten very well - the protein found in wheat, barley and rye. When people with celiac disease eat gluten it damages the small instestines. Symptoms are gas, bloating, indigestion, fatigue, and headaches. This disease is diagnosed by a blood test.