Celiac disease is an autoimmune illness in which a protein called gluten damages the small intestine's membrane. Gluten can be present in grains such as rye, barley, and wheat. Gluten causes an immunological reaction that damages the villi in the small intestine (small finger-like projections in the small intestine which promote absorption). The body's ability to absorb proteins, nutrients, lipids, vitamins, carbs, and minerals is hampered by the damage. This eventually leads to malnutrition.
