Some 3 million Americans suffer from celiac disease, a serious autoimmune disorder triggered by a reaction to gluten, mostly found in wheat products. For them, the search for gluten-free food has long meant joyless excursions to fern-filled health-food shops for comestibles that are often flavorless. Why, then, are so many people without the disease also devouring gluten-free foods? Many have done so out of perceived allergy concerns (gluten sensitivity is this decade’s lactose intolerance) or simply because it’s the diet buzzword du jour. Eager to cash in on that demand, mainstream manufacturers such as Campbell Soup and General Mills have helped create an industry estimated at $2.6 billion by SupermarketGuru. Now companies that had nothing to do with gluten are trying to slap “gluten-free” on their label. We’re talking about you, Star Vodka.