Celiac disease is a digestive disorder caused by a reaction to a protein called gluten, which is found in wheat, rye, and barley. When a person with celiac disease consumes gluten, an immune reaction occurs in their small intestine that damages its surface and makes it harder for them to absorb nutrients from food. Over time, this can cause deficiencies in several vitamins, minerals, and other necessary nutrients which can be especially dangerous for children.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), celiac disease affects around two million Americans, or about 1 in every 133 people. However, the actual number may be much higher due to difficulty in diagnosing the disease.