Celiac disease affects the small intestine. The immune system attacks the gluten protein found in wheat, rye and barely, and also damages the lining of the small intestine. What is the primary function of the small intestine?

When people with celiac disease eat gluten (a protein found in wheat, rye and barley), their body mounts an immune response that attacks the small intestine. These attacks lead to damage on the villi, small fingerlike projections that line the small intestine, that promote nutrient absorption.