Celiac disease is a hypersensitivity to gluten which is a protein found in wheat, rye, barley and oats. Although gluten sensitivity is not a food allergy, individuals with celiac disease avoid foods containing wheat, rye, barley and oats in the same way those with food allergies avoid the foods to which they are allergic. The gluten found in corn and rice does not contain this toxic portion.
Food is digested and absorbed in the small intestine.
The lining of the small intestine is lined with microscopic finger-like projections called villi designed to provide the maximum area for nutrient absorption. These villa contain digestive enzymes. In celiac disease, gluten ingestion results in damage and destruction of the villi. We can visualize the damage by thinking of shag carpeting changing into linoleum. It is easy to see why a flattening of the surface of the small intestine reduces its capacity to digest and absorb nutrients.