Working in lunchrooms, I have children with either a wheat allergy or something more troubling, called Celiac disease. Celiac is an illness caused by one’s immune system to gluten. What is gluten? Anyone who makes bread knows that you want it stretchy. You want to be able to put your finger into the dough and have it bounce back after letting it rest for a bit. What causes this reaction is the gluten. It is a protein found in wheat, barley or rye.