The results of a prospective multi-center survey are in: as many as three percent of Italians may suffer from non-celiac gluten sensitivity (NCGS), with symptoms ranging from irritable bowels to dermatitis. Researchers examining other nations with Western diets, such as the United States, the United Kingdom, continental Europe, Australia, and New Zealand, have found that as much as six percent of those populations adhere to wheat-free diets.
The aforementioned Italian study used questionnaires distributed to doctors in a variety of practices to determine the proportion of patients with gluten sensitivity not diagnosed as either wheat allergy or celiac disease. Physicians recorded their patients' gluten-related complaints, which included abdominal pain, constipation, and diarrhea, as well as non-gastrointestinal symptoms such as dermatitis, headache, and joint or muscle pain.
What has physicians and researchers alike scratching their heads over the apparent increased prevalance of gluten sensitivity or gluten avoidance is that many people who avoid gluten do not have a classic wheat allergy, in which the body reacts to wheat, or celiac disease, in which the immune system attacks the small intestine in the presence of wheat. Blood tests for celiac disease, for example, generally include screening for HLA-DQ2/DQ8, human leukocyte antigens. However, the Italian researchers found "no correlation" between NCGS and positive tests for HLA-DQ2/DQ8.
Complicating the issue of NCGS, as Norwegian researcher Knut Lundin notes, is that some people who experience unpleasant symptoms as a result of ingesting wheat either would or do experience the same symptoms when ingesting other items that are gluten-free, such as foods containing fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs). Some individuals experiencing a reduction or elimination of symptoms on a gluten-free diet, therefore, may actually be responding to the removal or reduction of FODMAPs in their diets.
What seems certain is that NCGS is a real, emerging diagnosis. A recent report from Asia confirms IgA (antibodies) against deamidated gliadin peptides (DGP) among a cohort of patients with irritable bowel syndrome (IBS). Another recent paper, this one from Spain, reports improvement in symptoms among both IBS and fibromyalgia patients adhering to a gluten-free diet. Research into the specific mechanisms of NCGS is difficult, because many patients choose to adopt a gluten-free diet without undergoing testing such as duodenal biopsy, so large data sets are difficult to obtain.