Gluten

Last Updated: September 28 2022

Gluten is a protein found in wheat and related grain products. It is involved in the rising of baked goods. People with celiac disease should not consume gluten, and it may also cause issues for people with other intestinal disorders. There is not much evidence to support the idea that gluten damages healthy intestinal tracts.

Gluten is most often used for




Don't miss out on the latest research

Become an Examine Insider for FREE to stay on top of the latest nutrition research, supplement myths, and more

    1.

    Sources and Structure

    1.1

    Sources and Structure

    Gluten refers to a group of proteins found in numerous grain products that form large interconnected structures called gluten-protein complexes during the cooking process. These complexes are responsible for bread rising while also providing structure and elasticity to the finished product.[1][2][3] Usually, gluten is not a single molecule. Rather, 75% of it is made up of proteins like prolamins (on a dry weight basis) with additional carbohydrates and lipids.[3] In the case of wheat glutens, the proteins are glutenins and gliadins. The latter are responsible for many of the intestinal concerns surrounding gluten due to their interactions with the immune system.[4] Wheat gluten is made up of at least 50 individual components.[3]

    Prolamins are found in other grains, including barley, rye, and corn. They are hordein, secalin, and zein respectively. Avenin, found in oats, is also a prolamin.[5] In a few cases, these prolamins can also influence celiac disease[6] as is the case with oat intolerance, [7] although gliadin is the major culprit.

    Gluten refers to a mixture of proteins called prolamins and other compounds, which exist in grains as storage proteins. Their content and manipulation can influence the composition and taste of bread products, but the gliadin prolamins cause a reaction in people with celiac disease.

    2.

    Peripheral Organ Systems

    2.1

    Intestines

    Gluten has been researched in the context of non-celiac gluten sensitivity (NCGS), which is sometimes called non-celiac wheat sensitivity.[8] NCGS is characterized by a sensitivity to gluten in people who do not have celiac disease. This effect was first observed in clinical practice, where patients showing symptoms of irritable bowel syndrome (IBS) sometimes responded well to gluten-free diets.[9] NCGS is neither celiac disease nor an allergic reaction to wheat and tends to be self-diagnosed (quite poorly, one study noted that 85.96% of subjects who self-reported intolerance to gluten did not have any response to gluten after testing[10]) with one study reporting an occurrance rate of 6.88% in a sample of 392 patients.[10]

    The first trial assessing NCGS found that, in a small group of people given gluten-containing or gluten-free muffins, reports of side-effects like tiredness and bloating were higher in the gluten group at 68% of subjects than in the control group (40%) with no apparent relation to HLA-DQ2 and/or HLA-DQ8.[9] A follow-up study of much larger size, investigating patients with IBS-like symptoms on a standard elimination diet (no cow's milk, eggs, tomato, or chocolate) who were randomized into two groups, one that ate no wheat and one that ate an additional 30g of wheat, noted that patients consuming wheat experienced more intestinal symptoms than the group not consuming wheat, when compared to their baseline values.[8] Other studies assessing patients showing IBS-like symptoms also noted that gluten seems to be comparatively worse than non-gluten controls or placebo.[11][12]

    A rechallenge study during which gluten was given before and after a dietary reduction in FODMAPs (short-chain carbohydrates known to promote intestinal distress by fermenting and producing gas[13]) found that gluten didn't promote intestinal distress on a low FODMAP diet,[14] suggesting that perhaps FODMAPs are a major cause of sensitivity. Wheat, rye, and barley are known to possess fructan FODMAPs.[13]

    People that report sensitivity to gluten despite not being diagnosed with celiac disease may exhibit intestinal symptoms of discomfort, but more research is needed to determine whether gluten or other carbohydrates like FODMAPs are the cause. There is a lack of evidence on people who claim gluten sensitivity but do not have any symptoms.

    3.

    Other Medical Conditions

    3.1

    Celiac Disease

    Celiac disease (CD) is a genetic disease[15] associated with gluten because when somebody with CD ingests gluten, their body undergoes an autoimmune response to varying degrees. This response can be relatively minor (studies have found people with CD who were previously unaware that they had it[14]) or potentially life-threatening. The best way to avoid this intestinal damage is to avoid gluten.[16][5] Initially, this effect was thought to be exclusive to Europeans, due to early problems with accurate diagnosis in developing countries.[17] CD is estimated to affect 0.5-1% of humans.[5] The risk of having CD rises to 20% if one or more parents have CD.[18]

    Diagnosis of celiac disease is still not 100% accurate, with biomarkers such as Human Leuckocyte Antigen (HLA) DQ2/8 and anti-endomysial/anti-tissue transglutaminase antibodies being important to the diagnosis.[19][20] Biopsies also used. However, biopsies may not be fully satisfactory[21] and a few celiacs are considered seronegative, meaning blood-based biomarkers seen in most CD sufferers are not present.[22] Regardless, unmanaged CD is associated with a greater mortality rate.[23]

    Gluten is not a single problematic compound, but rather a group of related prolamins that can trigger an autoimmune response. The most common prolamin is gliadin, a component of gluten.[24]

    Celiac disease is a somewhat rare (approximately 1% rate of occurrence) genetic disorder of the intestines during which the body exhibits an autoimmune responses after gliadin consumption, and potentially other related prolamins.

    References
    1.^Shwry PR, Tatham AS, Barro F, Barcelo P, Lazzeri PBiotechnology of breadmaking: unraveling and manipulating the multi-protein gluten complexBiotechnology (N Y).(1995 Nov)
    2.^Anjum FM, Khan MR, Din A, Saeed M, Pasha I, Arshad MUWheat gluten: high molecular weight glutenin subunits--structure, genetics, and relation to dough elasticityJ Food Sci.(2007 Apr)
    3.^Shewry PR, Halford NG, Belton PS, Tatham ASThe structure and properties of gluten: an elastic protein from wheat grainPhilos Trans R Soc Lond B Biol Sci.(2002 Feb 28)
    4.^Arentz-Hansen H, Körner R, Molberg O, Quarsten H, Vader W, Kooy YM, Lundin KE, Koning F, Roepstorff P, Sollid LM, McAdam SNThe intestinal T cell response to alpha-gliadin in adult celiac disease is focused on a single deamidated glutamine targeted by tissue transglutaminaseJ Exp Med.(2000 Feb 21)
    5.^Gujral N, Freeman HJ, Thomson ABCeliac disease: prevalence, diagnosis, pathogenesis and treatmentWorld J Gastroenterol.(2012 Nov 14)
    6.^Hardy MY, Tye-Din JA, Stewart JA, Schmitz F, Dudek NL, Hanchapola I, Purcell AW, Anderson RPIngestion of oats and barley in patients with celiac disease mobilizes cross-reactive T cells activated by avenin peptides and immuno-dominant hordein peptidesJ Autoimmun.(2015 Jan)
    7.^Arentz-Hansen H, Fleckenstein B, Molberg Ø, Scott H, Koning F, Jung G, Roepstorff P, Lundin KE, Sollid LMThe molecular basis for oat intolerance in patients with celiac diseasePLoS Med.(2004 Oct)
    8.^Carroccio A, Mansueto P, Iacono G, Soresi M, D'Alcamo A, Cavataio F, Brusca I, Florena AM, Ambrosiano G, Seidita A, Pirrone G, Rini GBNon-celiac wheat sensitivity diagnosed by double-blind placebo-controlled challenge: exploring a new clinical entityAm J Gastroenterol.(2012 Dec)
    9.^Biesiekierski JR, Newnham ED, Irving PM, Barrett JS, Haines M, Doecke JD, Shepherd SJ, Muir JG, Gibson PRGluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trialAm J Gastroenterol.(2011 Mar)
    10.^Capannolo A, Viscido A, Barkad MA, Valerii G, Ciccone F, Melideo D, Frieri G, Latella GNon-Celiac Gluten Sensitivity among Patients Perceiving Gluten-Related SymptomsDigestion.(2015)
    11.^Shahbazkhani B, Sadeghi A, Malekzadeh R, Khatavi F, Etemadi M, Kalantri E, Rostami-Nejad M, Rostami KNon-Celiac Gluten Sensitivity Has Narrowed the Spectrum of Irritable Bowel Syndrome: A Double-Blind Randomized Placebo-Controlled TrialNutrients.(2015 Jun 5)
    12.^Elli L, Tomba C, Branchi F, Roncoroni L, Lombardo V, Bardella MT, Ferretti F, Conte D, Valiante F, Fini L, Forti E, Cannizzaro R, Maiero S, Londoni C, Lauri A, Fornaciari G, Lenoci N, Spagnuolo R, Basilisco G, Somalvico F, Borgatta B, Leandro G, Segato S, Barisani D, Morreale G, Buscarini EEvidence for the Presence of Non-Celiac Gluten Sensitivity in Patients with Functional Gastrointestinal Symptoms: Results from a Multicenter Randomized Double-Blind Placebo-Controlled Gluten ChallengeNutrients.(2016 Feb 8)
    15.^Van Belzen MJ, Meijer JW, Sandkuijl LA, Bardoel AF, Mulder CJ, Pearson PL, Houwen RH, Wijmenga CA major non-HLA locus in celiac disease maps to chromosome 19Gastroenterology.(2003 Oct)
    16.^Rampertab SD, Pooran N, Brar P, Singh P, Green PHTrends in the presentation of celiac diseaseAm J Med.(2006 Apr)
    18.^Freeman HJRisk factors in familial forms of celiac diseaseWorld J Gastroenterol.(2010 Apr 21)
    19.^Samasca G, Sur G, Lupan I, Makovicky P, Freeman HJChallenges in the celiac disease diagnosis; Prague consensusGastroenterol Hepatol Bed Bench.(2017 Winter)
    20.^Bardella MT, Trovato C, Cesana BM, Pagliari C, Gebbia C, Peracchi MSerological markers for coeliac disease: is it time to change?Dig Liver Dis.(2001 Jun-Jul)
    21.^Taavela J, Popp A, Korponay-Szabo IR, Ene A, Vornanen M, Saavalainen P, Lähdeaho ML, Ruuska T, Laurila K, Parvan A, Anca I, Kurppa K, Mäki MA Prospective Study on the Usefulness of Duodenal Bulb Biopsies in Celiac Disease Diagnosis in Children: Urging CautionAm J Gastroenterol.(2016 Jan)
    22.^Volta U, Caio G, Boschetti E, Giancola F, Rhoden KJ, Ruggeri E, Paterini P, De Giorgio RSeronegative celiac disease: Shedding light on an obscure clinical entityDig Liver Dis.(2016 Sep)
    23.^Corrao G, Corazza GR, Bagnardi V, Brusco G, Ciacci C, Cottone M, Sategna Guidetti C, Usai P, Cesari P, Pelli MA, Loperfido S, Volta U, Calabró A, Certo M, Club del Tenue Study GroupMortality in patients with coeliac disease and their relatives: a cohort studyLancet.(2001 Aug 4)
    24.^Sollid LMMolecular basis of celiac diseaseAnnu Rev Immunol.(2000)