In some people, the body's immune system reacts to the gluten damaging the intestine. This autoimmune reaction, also known as Coeliac disease or celiac sprue, occurs in the small intestine and is triggered by gluten consumption. Celiac disease causes damage to the lining of the small intestine and prevents absorption of nutrients. Gluten proteins are found in wheat, barley and rye.

Some people with celiac disease do not have signs or symptoms. Sometimes symptoms resemble other disorders making the celiac diagnosis extremely difficult. Reports indicate that usually more than half of patients are undiagnosed or misdiagnosed with other conditions. Symptoms vary according to the age and level of damage to the small intestine.

As a consequence of malnutrition caused by the inability to absorb enough nutrients by the damaged small intestine may appear anemia, weight loss, and delayed growth. Sometimes people may develop dermatitis herpetiformis which is characterized by an intense burning and itching.