Celiac disease is a chronic autoimmune disorder that affects the small intestine. It occurs when an individual consumes gluten, which is found in wheat, barley and rye, causing damage to the lining of their small intestine. This can lead to malabsorption of nutrients, diarrhea, weight loss, and other symptoms. The only treatment for celiac disease is a strict gluten-free diet, which helps to heal the damaged tissue in the small intestine and alleviate symptoms.