After being confined to health-food stores for years, gluten-free foods have become the latest food fad. Supermarket aisles abound with products proudly labeled “Gluten free,” and many restaurants now offer gluten-free options. For people who can’t tolerate gluten, a protein found in wheat, rye, and barley, this abundance is a blessing. But lately it’s become hip to go gluten-free. Based on little or no evidence other than testimonials in the media, people have been switching to gluten-free diets to lose weight, boost energy, treat autism, or generally feel healthier. People who are sensitive to gluten may feel better doing this, but most won’t get a significant benefit from the practice—and will pay more for food because gluten-free products are expensive. It’s important to know that it can set you up for nutritional deficiencies such as a dearth of B vitamins and fiber.