Celiac disease happens when the immune system reacts abnormally to the gluten protein. It is, as such, an autoimmune condition, which means the immune system believes healthy cells are foreign invaders, attacking them by producing antibodies. Specifically with celiac disease, the body believes gliadin, produced by gluten, to be this threat. As a result, the intestine’s surface gets inflamed. This then flattens the villi, which are responsible for helping in the digestion of food, making it more difficult to properly digest the nutrients from your food.