Growing numbers of people are avoiding wheat and other grains because of celiac disease.
Gluten seems to be the food ingredient non grata these days. Bakers are coming up with recipes for gluten-free cupcakes and baguettes. Anheuser-Busch sells Redbridge, a gluten-free beer made from sorghum. And, of course, times being what they are, you can easily slip into an Internet swirl of blogs and Twittering about gluten-free foods. It's not just talk: cash registers are ringing. By some estimates, the sales of gluten-free foods have tripled since 2004.
Gluten-free food has become more popular partly because doctors are diagnosing more cases of celiac disease, an autoimmune disorder whose symptoms are triggered by gluten, the protein content in wheat, barley, rye, and spelt (an ancient form of wheat that's catching on as a health food). Celiac specialists say the disease isn't diagnosed as often as it should be. As a result, many people suffer with it for years, often after getting other — and incorrect — diagnoses and useless treatments.
But a growing number of the people dodging gluten fall into a gray area: they don't have celiac disease but seem to be unable to digest gluten properly. There are no tests or strict criteria for this problem, aside from simple trial and error with a gluten-free diet. Often people self-diagnose. It's hard to know what's going on. Some people may be getting caught up in a food fad. But many others probably do have a real problem digesting gluten or perhaps the sugars in some of these grains, a condition akin to the lactose intolerance that makes it hard for many people to digest dairy foods. Their problem is not as well-defined or well-understood as celiac disease but they have a problem nonetheless.
There's a third group of gluten-free converts: people who are blaming gluten for a wide range of medical conditions, not just gastrointestinal distress. For example, there's a fairly loud Internet "buzz" about autistic children improving once they're on a gluten-free diet.
There's good, solid evidence of an overlap between celiac disease and other autoimmune disorders, particularly type 1 diabetes. And celiac disease and other autoimmune disorders sometimes have neurological effects — peripheral neuropathy, for example, which involves nerve damage that results in numbness and pain.
But based on what is currently known, it's a big leap to attributing autism and other problems to gluten, and an even bigger one to prescribing gluten-free eating as a treatment. It's possible that some people benefit from a gluten-free regimen for reasons that have less to do with gluten and much more to do with the structure involved in planning and sticking to such a strict eating plan.
Misreading the situation
Gluten is an imprecise term that shifts meaning depending on the context. Gluten comes, not surprisingly, from the Latin word for glue, and cookbooks define it as the protein-based substance that makes dough resilient and stretchy. If you're making bread, you want gluten in the dough, so that when it's baking the walls of the little air pockets formed by yeast expand but don't burst open. But if you're making cookies or a pie crust, you want to keep the gluten content of the dough and batter low. Otherwise, your results will be tough and gummy.
In the context of celiac disease, gluten refers to the protein of grains capable of provoking an autoimmune response. Other grains also contain protein, but wheat, barley, rye, and spelt contain varieties that aren't broken down by digestive enzymes. In wheat, the difficult-to-digest protein is gliadin; in rye, it's secalin; and in barley, hordein.
These proteins don't faze the guts of most of us. But in people with celiac disease, when they get absorbed into the walls of the small intestine, the immune system misreads the situation, views them as intruders, and unleashes a furious inflammatory response that damages tissue (see illustration). The inside of a normal, healthy small intestine is carpeted with millions of fingerlike projections called villi that produce digestive enzymes and soak up nutrients. The misguided immune response triggered by the gluten proteins sometimes attacks these villi, so they lose their slender shape and become short and stubby, even flat. When that happens, the villi produce fewer digestive enzymes and absorb fewer nutrients.