Celiac disease is an autoimmune disorder affecting the small intestine. It causes the body to attack the villi (small protrusions that sweep food through the intestines) upon ingestion of food containing glutenin or gliadin proteins, which are found in wheat, rye, and barley.
Celiac disease is often referred to as a gluten allergy. This does not reflect current understanding of the disorder, as the body attacks not the perceived allergen but rather itself. Nonetheless, the treatment is the same as for a gluten allergy: strict abstinence from all foods containing gluten.