6-7% of the population may get stomach aches, joint pain, and other symptoms from the proteins in wheat and some other grains.

RODALE NEWS, EMMAUS, PA—Gluten-free foods are rapidly proliferating on grocery store shelves. Gluten-free is the one of the fastest growing segments of the food industry (second only to foods free of genetically modified organisms, or GMOs). The foods were intended for people with wheat allergies, or those suffering from celiac disease, a condition in which people have an autoimmune response to wheat gluten and related proteins in barley and rye. But a growing segment of the population are turning to these products to alleviate a variety of gastrointestinal problems. And new research supports the concept of "gluten sensitivity," in which people without celiac disease show symptoms in response to gluten.

Gluten sensitivity is a digestive health problem like celiac disease, in that people who ingest wheat, rye, or barley suffer stomachaches, bloating, and diarrhea. But the gluten sensitive don't test positive for celiac disease, nor do they have the characteristic intestinal damage. "For whatever reason, people have symptoms that mimic celiac disease, but they test negative to the screenings. And they clearly get better with a gluten-free diet," says Alessio Fasano, MD, medical director of the Center for Celiac Research at the University of Maryland School of Medicine and a leading researcher on celiac disease and related disorders. Based on the number of people who've visited his clinic over the past four to five years, he estimates that anywhere from 6 to 7 percent of the population suffers from gluten sensitivity, compared to about 1 percent of the population that's likely to have celiac disease.

The disorder has been met with skepticism in the medical community, but that may soon change. A recent study published in the American Journal of Gastroenterology found that gluten-free diets can in fact help people who claim to be gluten sensitive but don't show any signs of celiac disease.

THE DETAILS: The authors recruited 34 adults who'd been screened and had negative test results for celiac disease, but reported gastrointestinal problems that improved on a gluten-free diet. The study authors had muffins and bread specially prepared for the experiment, half of which contained gluten and half of which were gluten-free. The subjects were randomly assigned to either group, and told to eat one muffin and two slices of bread per day for 6 weeks. Neither group knew whether they were eating the gluten-free baked goods or the gluten-containing goods. Each week, study participants filled out questionnaires related to symptoms such as bloating, abdominal pain, nausea, and fatigue, which are all characteristic of non-celiac gluten sensitivity. Within the first week, all of the people in the gluten group reported an increase in severity of symptoms, and by the end of the study, 68 percent reported an overall worsening of symptoms over the six-week period. People in the gluten-free group also saw a worsening of their symptoms, but the change occurred gradually over time, not in the first week. By the end of the study, 40 percent of that group reported a worsening of symptoms.

WHAT IT MEANS: Very little is known about non-celiac gluten sensitivity, and a 2009 study in this same journal even dubbed it the "no-man's-land" of gastrointestinal problems. "We are with gluten sensitivity where we were with celiac disease 10 years ago," says Dr. Fasano. "There's still a lot of skepticism of it in the medical community and lack of information and confusion about the condition." Much of that has to do with the simple fact that gluten-sensitivity symptoms are so vague, and so easily confused with other disorders. The three most frequent symptoms of the disorder are stomachaches and irregular bowel movements, which often get confused with irritable bowel syndrome, joint pain that's diagnosed as arthritis, and a "foggy mind" or headaches that, coupled with fatigue, are mistaken for chronic fatigue syndrome or fibromyalgia, says Dr. Fasano. "It's really a mixed bag of stuff."