While about 1% of the US population is estimated to have Celiac Disease, the number of people who have “non celiac gluten sensitivity” is thought to be as much as six to seven times higher. What exactly is non celiac gluten sensitivity? And how is it diagnosed? These questions were addressed recently by a group of fifteen recognized experts from around the world. The consensus, recently published online, is entitled “Spectrum of gluten-related disorders: consensus on new nomenclature and classification.” 1
The consensus authors note that the market for gluten-free food and beverages grew at the remarkable rate of 28% from 2004 to 2011. Meanwhile, though approximately three million Americans have celiac disease (CD), only a small fraction of these are diagnosed. So what is contributing to this huge market? It’s thought that much of this growth can be traced to people who are experiencing a reaction to gluten, but who do not have celiac disease or wheat allergy. These people would fall into the category of non celiac gluten sensitivity (NCGS).
The symptoms of non celiac gluten sensitivity are similar to those of celiac disease, but with a higher prevalence of non–gastrointestinal symptoms. Common symptoms include behavioral changes, bone or joint pain, leg numbness, muscle cramps and chronic fatigue. Symptoms alone can’t distinguish between celiac disease and non celiac gluten sensitivity.
Since symptoms are similar to those of CD, NCGS patients would generally undergo CD antibody testing. But in the case of NCGS, an individual would not test positive for specific celiac-related antibodies, such as tTG autoantibodies, nor would the patient exhibit other autoimmune issues, as would be the case with CD. These patients would also have negative immune-allergy tests to wheat. A small intestine biopsy would rule out celiac disease, as the intestine of patients with NCGS is usually normal. Regarding genetic predisposition and markers, nearly all people with celiac disease test positive for the genes HLA-DQ2 and HLA-DQ8, but in patients with NCGS, this number is only about 50%. Finally, the diagnosis would be confirmed when a patient shows a resolution of symptoms when started on a gluten-free diet, followed by a return of symptoms when gluten is re-introduced. (The authors note that the gluten-free diet should ideally be implemented in a “blinded” fashion, meaning that the patient would not be aware of whether or not he/she is ingesting gluten. This would rule out a placebo effect, that is, an improvement seen in symptoms as a result of merely believing that a gluten-free diet is in place. Practically, though, without being in a clinical setting it’s nearly impossible to remove gluten from the diet in a “blinded” fashion. )
Little is known about what causes NCGS and more research is needed. It’s thought that NCGS may involve some type of immune response which, however, is not an auto-immune response, as is the case in celiac disease. But again, this is not clearly defined. Also unknown is whether patients with NCGS have the same gluten threshold as CD patients; in other words, do they need to avoid even minute amounts of gluten as do CD patients? The duration of the condition is also unknown; it may or may not be a lifelong condition like celiac disease.
The article concludes by presenting an interesting theory regarding the apparent population-wide increase in gluten sensitivity being experienced. The authors state that the high frequency and wide range of adverse reactions to gluten may be related to changes in wheat varieties which have occurred over thousands of years. Ten thousand years ago wheat varieties contained smaller amounts of the gluten peptide.
But gradually over time, and especially since the Middle Ages, there has been a selection for higher gluten varieties of wheat. The changes in this aspect of wheat have been dictated by function, not by health and nutrition. Higher gluten flour makes for products with more rise, chewiness and volume, characteristics which both food manufacturers and consumers often prefer. The authors speculate that the human organism is vulnerable to adverse affects of gluten, particularly due to a lack of adequate adaptation in the gastrointestinal and immunological systems. In addition, they point out, gluten in the food supply is abundant and diffusely spread among most populations.