Celiac disease, or gluten sensitivity, is an autoimmune inflammatory disease that damages the villi - the small, finger-like projections that line the small intestine. For people with celiac disease, eating foods containing gluten - a protein found in wheat and other grains - sets off an autoimmune reaction that causes the villi to shorten and eventually flatten. Without healthy villi, a person becomes malnourished, regardless of the quantity of food eaten. Left untreated, celiac disease can lead to serious long-term conditions such as cancer, osteoporosis, anemia and seizures, and may become life threatening.