Bread, once the indispensable "staff of life," is now feared by many as the stuff of distress. It's not bread per se, but rather gluten — the protein content in wheat, barley, and rye — that has become a food ingredient non grata. Gluten, whose name comes from the Latin root for glue, is an umbrella term for the proteins gliadin (in wheat), secalin (in rye), and hordein (in barley). Bakers know it as the substance that makes dough resilient and stretchy. If you're making bread, you want gluten in the dough, so that the walls of the little air pockets formed by yeast expand but don't burst open during baking.
Gluten has bubbled to the top of the list of food perpetrators partly because doctors are diagnosing more cases of celiac disease, an autoimmune disorder whose symptoms are triggered by gluten. And a growing number of people who don't have celiac disease but suffer many of its symptoms have been classified as "gluten sensitive"; or "gluten intolerant." Gluten has been held suspect in a wide range of additional medical conditions, including arthritis and autism, although there is little scientific evidence to support those associations.