Gluten Digestion in the Face of Inadvertent Exposure

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1368550803996Dr Carrie Decker ND, explores the potential management of indavertent ingestion of gluten, which for those people needing to exclude exposure to these proteins and lead a life that includes eating foods that have not been prepared at home, can be a significant risk to well being.

Coeliac disease (CD) is the most studied and broadly recognised disease associated with the immune reaction to gluten consumption, however other types of ‘gluten sensitivity’ also exist. These conditions are broadly known as Non-Coeliac Gluten Sensitivity (NCGS). The immune response to gluten proteins and polypeptide regions varies, but may involve the innate immune system, class I or class II mediated reactions, and antibody recognition.[1] The topic of NCGS is being increasingly studied, as is evidenced in the following quote extracted from an article in Nutrients:- “Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders”[2]:

“The publications on CD doubled every 20 years from approximately 2500 in the period of 1950–70 to ~9500 in the period 1991–2010, with already more than 2000 papers published between 2011 and 2013. Conversely, there were almost no scientific reports on NCGS before 1970 and only a handful number of papers have been published ever since, most of them after 2005. The increase interest in NCGS is testified by the decreased NCGS/CD publication ratio that dropped from 1:438 in the period 1950–70 to 1:10 in the period 2010–13.”

The diagnosis of NCGS must exclude the possibility of coeliac disease and wheat allergy. Beyond this it is characterised by symptoms which occur after gluten ingestion, with improvements within hours or days after elimination, and relapse following gluten introduction. Individuals with NCGS commonly report a personal history of food allergy and atopy in infancy.[3] Digestive symptoms may manifest similar to irritable bowel syndrome, and relationships have also been suggested between NCGS and neuropsychiatric disorders, particularly autism, schizophrenia, and a vulnerability for dementia.2,[4] Alterations of the normal commensal gut microbiome in NCGS has been described to cause gut inflammation, diarrhea, constipation, visceral hypersensitivity, abdominal pain, dysfunctional metabolic state, and peripheral immune and neuro-immune communication.

A distinct manner of testing for NCGS currently does not exist. Under further investigation is a process in which the testing includes the immunoglobulin G (IgG) antigliadin antibodies and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts. Indications are that it could be useful to identify NCGS patients.3

In the instance of both coeliac disease and NCGS the most effective approach for the resolution of symptoms and related complications is the dietary elimination of gluten-containing foodstuff from the diet. However, such a diet is often difficult to maintain due the frequent usage of gluten in the food industry, and inadvertent trace exposures are common in settings such as restaurants or other food preparation facilities where strict policies to avoid gluten cross-contamination are not imposed.

Dipeptidyl peptidase IV (DDP IV) is an exo-peptidase enzyme involved in the degradation of proline-rich proteins such as gliadin. On its own DPPIV has a very limited proteolytic effect as it acts on the terminal peptide bonds, preferentially cleaving the X-proline or X-alanine dipeptides from the N terminus of polypeptides.[5] It also has an optimal function at neutral pH so that it is unlikely to be active during stomach passage. It has been observed that proteolytic activity of several gluten-digestion specific preparations containing high amounts of DDP IV with other proteases could only partly neutralize gluten proteins and are ineffective in degrading immunogenic gluten fragments from both the α- and γ-gliadins.[6] For this reason such enzymes primarily comprised of DPP IV and amylase are not likely to be beneficial for either coeliac disease or NCGS as proline-specific endo-peptidases to break down the internal peptide bonds are missing.

Substances which have proline-specific endo-peptidase action have been isolated, and are being studied for more complete degradation of gluten.[7] These enzymes have been studied in both in vitro and in vivo settings, and have been shown efficiently degrade gluten and be well tolerated in individuals with coeliac disease.6,[8],[9] In the placebo-controlled pilot study investigating the use of a gluten specific endopeptidase in individuals with coeliac disease, increased tissue transglutaminase (tTG) immunoglobulin A (IgA) deposits were seen in the placebo group after a period of gluten consumption compared with the group receiving the endo-peptidase supplement with gluten consumption. However no significant deterioration was observed in either group so further conclusions could not be drawn.9

A decrease in intestinal DPP IV activity has been shown to correlates with the level of mucosal damage in patients with coeliac disease and other malabsorption syndromes.[10] The level and activity of other digestive enzymes found on the brush border and secreted by the intestinal epithelial cells are also decreased with mucosal damage which may occur with coeliac disease or other enteric infection.[11],[12],[13],[14] For these reasons a comprehensive digestive enzyme including both exo – and endo-peptidase for the purpose of digestion of gluten, as well as other enzymes including lipase, lactase, amylase, and protease for support in digestion of carbohydrates, fats and proteins may often be beneficial.


[1] Ciccocioppo R, et al. The immune recognition of gluten in coeliac disease. Clin Exp Immunol. 2005 Jun;140(3):408-16. View Full Paper

[2] Catassi C, et al. Non-Celiac Gluten sensitivity: the new frontier of gluten related disorders. Nutrients. 2013 Sep 26;5(10):3839-53. View Full Paper

[3] Mansueto P, Seidita A, D’Alcamo A, Carroccio A. Non-celiac gluten sensitivity: literature review. J Am Coll Nutr. 2014;33(1):39-54. View Abstract

[4] Daulatzai MA. Non-celiac gluten sensitivity triggers gut dysbiosis, neuroinflammation, gut-brain axis dysfunction, and vulnerability for dementia. CNS Neurol Disord Drug Targets. 2015;14(1):110-31. View Abstract

[5] Thoma R, et al. Structural basis of proline-specific exopeptidase activity as observed in human dipeptidyl peptidase-IV. Structure. 2003 Aug;11(8):947-59. View Full Paper

[6] Janssen G, et al. Ineffective degradation of immunogenic gluten epitopes by currently available digestive enzyme supplements. PLoS One. 2015 Jun 1;10(6):e0128065. View Full Paper

[7] Tack GJ, et al. Consumption of gluten with gluten-degrading enzyme by celiac patients: a pilot-study. World J Gastroenterol. 2013 Sep 21;19(35):5837-47. View Full Text

[8] Mitea C, et al. Efficient degradation of gluten by a prolyl endoprotease in a gastrointestinal model: implications for coeliac disease. Gut. 2008 Jan;57(1):25-32. Epub 2007 May 9. View Abstract

[9] Montserrat V, Bruins MJ, Edens L, Koning F. Influence of dietary components on Aspergillus niger prolyl endoprotease mediated gluten degradation. Food Chem. 2015 May 1;174:440-5. View Full Text

[10] Detel D, Persić M, Varljen J. Serum and intestinal dipeptidyl peptidase IV (DPP IV/CD26) activity in children with celiac disease. J Pediatr Gastroenterol Nutr. 2007 Jul;45(1):65-70. View Abstract

[11] Prasad KK, Thapa BR, Nain CK, Sharma AK, Singh K. Brush border enzyme activities in relation to histological lesion in pediatric celiac disease. J Gastroenterol Hepatol. 2008 Aug;23(8 Pt 2):e348-52. View Abstract

[12] Taylor CJ, Hart A, Batt RM, McDougall C, McLean L. Ultrastructural and biochemical changes in human jejunal mucosa associated with enteropathogenic Escherichia coli (0111) infection. J Pediatr Gastroenterol Nutr. 1986 Jan;5(1):70-3.View Abstract

[13] Agus SG, Dolin R, Wyatt RG, Tousimis AJ, Northrup RS. Acute infectious nonbacterial gastroenteritis: intestinal histopathology. Histologic and enzymatic alterations during illness produced by the Norwalk agent in man. Ann Intern Med. 1973 Jul;79(1):18-25.View Abstract

[14] Welsh JD, Poley JR, Hensley J, Bhatia M. Intestinal disaccharidase and alkaline phosphatase activity in giardiasis. J Pediatr Gastroenterol Nutr. 1984;3(1):37-40. View Abstract


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