A gluten-free diet is a diet that excludes foods containing gluten. Gluten is a protein complex found in wheat, barley, rye and triticale.. A gluten-free diet is the only medically accepted treatment for celiac disease, Being gluten intolerant can often mean a person may also be wheat intolerant as well as suffer from the the related inflammatory skin condition dermatitis herpetiformis, There are a smaller minority of people who suffer from wheat intolerance alone and are tolerant to gluten.