An autoimmune disease that damages the inner portion of the small intestine (duodenum), and causes malabsorption, causing malnourishment. The reaction is caused by eating foods that have gluten in them. Gluten is found in wheat, rye, and barley, and possibly can contaminate oats. Symptoms of celiac disease include nausea, vomiting, intestinal cramping, and malabsorption. These symptoms subside when gluten is avoided. The inside of the small intestine has small, finger-like projections called villi that help with absorption of nutrients. Flattened villi are often associated with the disease, and their appearance on biopsy/endoscopic evaluation is considered the gold standard for diagnosis in a person who is consuming gluten-containing foods. Blood antibodies to the gluten, gliadin, and transglutimase may also assist with diagnosis.