Celiac Disease is an autoimmune disease triggered by the presence of gluten in the small intestine. The body mistakes the gluten for a dangerous invader, and sends white blood cells to the area. The cells cause inflammation. The inflammation can cause digestive upsets such as stomach aches and diarrhea. If the intestine remains chronically inflamed, the villi within the intestine become flattened. This prevents the body from absorbing nutrients, which causes all kinds of problems.
When a person with celiac disease eats a gluten free diet, the intestine returns to normal, healthy functioning. This does not mean the disease has been cured; celiac is chronic. However, as long as gluten is avoided, people with celiac can enjoy good health.