Celiac Disease and Non-Celiac Gluten Sensitivity
Understanding Non-Celiac Gluten Sensitivity
Some people who do not have celiac disease or a wheat or gluten allergy may still experience symptoms in response to gluten ingestion. These symptoms can resemble those associated with celiac disease and may include gastrointestinal symptoms and non-intestinal symptoms. This newly-recognized gluten-related syndrome has been named non-celiac wheat sensitivity or non-celiac gluten sensitivity. Current knowledge about non-celiac gluten sensitivity is limited, and many unresolved questions remain to be clarified (Volta 2013; Sapone 2012).
Non-celiac gluten sensitivity is not an autoimmune disease and does not result in the same damage to the lining of the small intestine that is characteristic of celiac disease. Overall, non-celiac gluten sensitivity is less severe than celiac disease. The mechanism underlying the development of non-celiac gluten sensitivity is not clear, though it is known to be different from that of celiac disease and wheat allergy. There are conflicting reports, for example, as to whether people with non-celiac gluten sensitivity have altered gut barrier function (Biesiekierski 2011; Sapone 2011; Vazquez-Roque 2013).
As in celiac disease, the fast-acting or “innate” immune system is activated in non-celiac gluten sensitivity, causing moderate inflammation of the intestinal lining. However, unlike celiac disease, most evidence indicates that the adaptive immune system (also called acquired or specific immunity) is not activated in non-celiac gluten sensitivity (Lundin 2012; Catassi 2013; Volta 2013; Sapone 2011; Goronzy 2012; Volta, Di Giorgio 2012).
Gluten proteins may not be the sole or main triggers of non-celiac gluten sensitivity; other non-gluten components in wheat may play a role as well (Bucci 2013; Biesiekierski 2013). For instance, amylase-trypsin inhibitors are non-gluten proteins in wheat that are resistant to digestion. They are the primary allergens in Baker’s asthma, an occupational asthma that afflicts bakers and others exposed to grain and wheat flour dust (Salcedo 2011; James 1997). They can provoke inflammation and immune reactions in the cells of celiac and non-celiac patients, though their potential role in non-celiac gluten sensitivity has yet to be explored (Junker 2012).
Other non-protein constituents of wheat could elicit gastrointestinal symptoms in people with non-celiac gluten sensitivity. FODMAPs—an acronym for fermentable oligo-, di-, and monosaccharides and polyols—are poorly digested and incompletely absorbed carbohydrates found in a wide range of foods including gluten-containing grains, fruits, foods made with high fructose corn syrup or sugar alcohols, and dairy (SHC 2014).
FODMAPs are easily fermented by gut bacteria, which can result in gas, bloating, and diarrhea, symptoms shared by both irritable bowel syndrome and non-celiac gluten sensitivity (Barrett 2012; Magge 2012).
A 2013 randomized controlled trial in 37 patients with non-celiac gluten sensitivity and irritable bowel syndrome found that gluten did not produce negative effects when FODMAPs were restricted in the diet. The study authors concluded that non-celiac gluten sensitivity may not be distinct from reactions to FODMAPs (Biesiekierski 2013).