In people with coeliac disease, the immune system reacts abnormally to gluten (a protein found in wheat, rye, barley and oats), causing small bowel damage. The tiny, finger-like projections which line the bowel (villi) become inflamed and flattened. This is referred to as villous atrophy. Villous atrophy reduces the surface area of the bowel available for nutrient absorption, which can lead to various gastrointestinal and malabsorptive symptoms. Symptoms can also be caused by inflammation in other parts of the body