THE NEWS: Gluten-free products are flying off grocery shelves as cases of the once rare celiac disease increase, but some estimate that more than half of consumers buying the products don’t react to gluten.

WHAT IS GLUTEN?: In the worst cases, the protein found in wheat, rye and barley triggers celiac disease, which causes abdominal pain, bloating and intermittent diarrhea. Those with the ailment don’t absorb nutrients well and can suffer weight loss, fatigue, rashes and other problems.