The autoimmune disease in which the immune system attacks the lining of the small intestine is celiac disease. In genetically susceptible people, gluten triggers an abnormal immune response that damages the intestinal mucosa.
Gluten is a group of proteins found in wheat, barley, and rye. The resulting inflammation can flatten or destroy the small intestine’s villi—tiny projections that increase the surface area available for absorbing nutrients. This can lead to diarrhea, weight loss, iron-deficiency anemia, fatigue, weak bones, or poor growth in children. Some people have few or no digestive symptoms.
Celiac disease is different from a wheat allergy and from non-celiac gluten sensitivity. It is also distinct from irritable bowel syndrome, Crohn’s disease, and ulcerative colitis, although these conditions can produce overlapping symptoms. Diagnosis commonly involves antibody blood tests followed by a small-intestine biopsy, and testing is most reliable while the person is still eating gluten.
The established treatment is a strict, lifelong gluten-free diet. Removing gluten usually allows the intestinal lining to heal and reduces the risk of nutritional complications. Even small amounts of gluten can trigger intestinal injury in some people.