Virtually everyone has heard about gluten-free diets. A gluten-free diet is medically necessary for those with celiac disease, an autoimmune condition. It can be thought of as an extreme allergy to gluten. Those with celiac disease incur damage to the intestinal tract when they eat wheat gluten, leading to weight loss, iron deficiency, diarrhea, fatigue, and malabsorption. People also avoid gluten because it gives them unpleasant symptoms or they...