Gluten is a protein found in wheat, rye, and barley that can cause a spectrum of disorders. Celiac disease is an autoimmune disorder triggered by gluten that damages the small intestine and can cause problems absorbing nutrients. Wheat allergy is an immune reaction to wheat proteins. While celiac disease requires strict gluten avoidance, gluten sensitivity is when individuals experience negative symptoms after gluten ingestion. The gluten-free diet is only medically necessary for those with celiac disease to prevent intestinal damage but removing gluten alone does not determine diet quality.