Gluten

Source: Wikipedia, the free encyclopedia.
For the food made from gluten, see Seitan.
Examples of sources of gluten (clockwise from top): wheat as flour, spelt, barley, and rye as rolled flakes

Gluten is a structural protein naturally found in certain cereal grains.[1] The term gluten usually refers to a wheat grain's prolamins, specifically glutelin proteins, that naturally occur in many cereal grains, and which can trigger celiac disease in some people. The types of grains that contain gluten include all species of wheat (common wheat, durum, spelt, khorasan, emmer and einkorn), and barley, rye, and some cultivars of oat; moreover, cross hybrids of any of these cereal grains also contain gluten, e.g. triticale.[2][3] Gluten makes up 75–85% of the total protein in bread wheat.[4][5]

Glutens, especially Triticeae glutens, have unique viscoelastic and adhesive properties, which give dough its elasticity, helping it rise and keep its shape and often leaving the final product with a chewy texture.[4][6][7] These properties, and its relatively low cost, make gluten valuable to both food and non-food industries.[7]

Wheat gluten is composed of mainly two types of proteins: the

zeins) and rice (rice protein), are sometimes called gluten, but they do not cause harmful effects in people with celiac disease.[2]

Bread produced from wheat grains contains gluten.

Gluten can trigger adverse,

gluten ataxia and other neurological disorders.[11][12][13][14] These disorders are treated by a gluten-free diet.[14]

Uses

Wheat, a prime source of gluten

Bread products

Gluten forms when glutenin molecules cross-link via

fermentation produces carbon dioxide bubbles, which, trapped by the gluten network, cause the dough to rise. Baking coagulates the gluten, which, along with starch, stabilizes the shape of the final product. Gluten content has been implicated as a factor in the staling of bread, possibly because it binds water through hydration.[16][17]

Cross-section of a baguette showing a strong gluten network

The formation of gluten affects the texture of the baked goods.[4] Gluten's attainable elasticity is proportional to its content of glutenins with low molecular weights, as this portion contains the preponderance of the sulfur atoms responsible for the cross-linking in the gluten network.[18][19] Using flour with higher gluten content leads to chewier doughs such as those found in pizza and bagels, while using flour with less gluten content yields tender baked goods such as pastry products.[20]

Generally,

pie crust
, is desired.

The strength and elasticity of gluten in flour is measured in the baking industry using a farinograph. This gives the baker a measurement of quality for different varieties of flours when developing recipes for various baked goods.[4][21][22]

Added gluten

In industrial production, a

atomizer nozzle into a drying chamber, where it remains at an elevated temperature for a short time to allow the water to evaporate without denaturing the gluten.[citation needed] The process yields a flour-like powder with a 7% moisture content, which is air cooled and pneumatically transported to a receiving vessel. In the final step, the processed gluten is sifted and milled to produce a uniform product.[23]

This flour-like powder, when added to ordinary flour dough, may help improve the dough's ability to increase in volume. The resulting mixture also increases the bread's structural stability and chewiness.[24] Gluten-added dough must be worked vigorously to induce it to rise to its full capacity; an automatic bread machine or food processor may be required for high-gluten kneading.[25] Generally, higher gluten levels are associated with higher overall protein content.[26]

Imitation meats

Further information on the use of gluten in cooking:
Wheat gluten (food)
Photo of vegetarian "mock duck" made of wheat gluten in a brine with seasonings.
Gluten is often used in imitation meats (such as this mock duck) to provide supplemental protein in vegetarian diets

Gluten, especially

vegetarian diets. In home or restaurant cooking, wheat gluten is prepared from flour by kneading the flour under water, agglomerating the gluten into an elastic network known as a dough, and then washing out the starch.[4]

Other consumer products

Gluten is often present in

celiac disease and gluten sensitivities. The protein content of some pet foods may also be enhanced by adding gluten.[29]

Gluten is also used in cosmetics, hair products and other dermatological preparations.[30]

Disorders

Main articles:
Gluten-sensitive idiopathic neuropathies

"Gluten-related disorders" is the umbrella term for all diseases triggered by gluten, which include

gluten ataxia and dermatitis herpetiformis (DH).[13]

Pathophysiological research

The gluten peptides are responsible for triggering gluten-related disorders.[31] In people who have celiac disease, the peptides cause injury of the intestines, ranging from inflammation to partial or total destruction of the intestinal villi.[32][33] To study mechanisms of this damage, laboratory experiments are done in vitro and in vivo.[34][33] Among the gluten peptides, gliadin has been studied extensively.[31]

In vitro and in vivo studies

In the context of celiac disease, gliadin peptides are classified in basic and clinical research as immunogenic, depending on their mechanism of action:[31][35]

At least 50 epitopes of gluten may produce cytotoxic, immunomodulatory, and gut-permeating activities.[37]

The effect of oat peptides (avenins) in celiac people depends on the oat cultivar consumed because of prolamin genes, protein amino acid sequences, and the immunotoxicity of prolamins which vary among oat varieties.[39][40][41] In addition, oat products may be cross-contaminated with the other gluten-containing cereals.[40]

Incidence

As of 2017, gluten-related disorders were increasing in frequency in different geographic areas.[38][42][43][44] Some suggested explanations for this increase include the following: the growing westernization of diets,[42] the increasing use of wheat-based foods included in the Mediterranean diet,[45][46] the progressive replacement of rice by wheat in many countries in Asia, the Middle East, and North Africa,[42] the higher content of gluten in bread and bakery products due to the reduction of dough fermentation time,[47][48] and the development in recent years of new types of wheat with a higher amount of cytotoxic gluten peptides,[47][49] However, a 2020 study that grew and analyzed 60 wheat cultivars from between 1891 and 2010 found no changes in albumin/globulin and gluten contents over time. "Overall, the harvest year had a more significant effect on protein composition than the cultivar. At the protein level, we found no evidence to support an increased immunostimulatory potential of modern winter wheat."[50]

Celiac disease

Main article: Coeliac disease
Medical animation still showing flattened intestinal villi.

intestinal villi.[55]

CD affects approximately 1–2% of the general population,

diabetes mellitus type 1, thyroiditis,[59] gluten ataxia, psoriasis, vitiligo, autoimmune hepatitis, dermatitis herpetiformis, primary sclerosing cholangitis, and more.[51][59]

CD with "classic symptoms", which include gastrointestinal manifestations such as chronic diarrhea and abdominal distention, malabsorption, loss of appetite, and impaired growth, is currently the least common presentation form of the disease and affects predominantly small children generally younger than two years of age.[51][53][56]

CD with "non-classic symptoms" is the most common clinical type[53] and occurs in older children (over two years old),[53] adolescents, and adults.[53] It is characterized by milder or even absent gastrointestinal symptoms and a wide spectrum of non-intestinal manifestations that can involve any organ of the body, and very frequently may be completely asymptomatic[56] both in children (at least in 43% of the cases[60]) and adults.[56]

Asymptomatic CD (ACD) is present in the majority of affected patients and is characterized by the absence of classical gluten-intolerance signs, such as diarrhea, bloating, and abdominal pain. Nevertheless, these individuals very often develop diseases that can be related with gluten intake. Gluten can be degraded into several morphine-like substances, named gluten exorphins. These compounds have proven opioid effects and could mask the deleterious effects of gluten protein on gastrointestinal lining and function.[61]

Non-celiac gluten sensitivity

Main article: Non-celiac gluten sensitivity

Non-celiac gluten sensitivity (NCGS) is described as a condition of multiple symptoms that improves when switching to a gluten-free diet, after celiac disease and wheat allergy are excluded.[62][63] Recognized since 2010,[64][65] it is included among gluten-related disorders.[64] Its pathogenesis is not yet well understood, but the activation of the innate immune system, the direct negative effects of gluten and probably other wheat components, are implicated.[65][36]

NCGS is the most common syndrome of

gluten intolerance,[64][66] with a prevalence estimated to be 6-10%.[12] NCGS is becoming a more common diagnosis, but its true prevalence is difficult to determine because many people self-diagnose and start a gluten-free diet, without having previously tested for celiac disease or having the dietary prescription from a physician.[67] People with NCGS and gastrointestinal symptoms remain habitually in a "no man's land", without being recognized by the specialists and lacking the adequate medical care and treatment.[68] Most of these people have a long history of health complaints and unsuccessful consultations with numerous physicians, trying to get a diagnosis of celiac disease, but they are only labeled as irritable bowel syndrome.[68][69] A consistent although undefined number of people eliminate gluten because they identify it as responsible for their symptoms and these improve with the gluten-free diet, so they self-diagnose as NCGS.[68][69]

People with NCGS may develop gastrointestinal symptoms, which resemble those of

fatigue, fibromyalgia, atopic diseases, allergies, neurological diseases, or psychiatric disorders, among others.[58][65][70] The results of a 2017 study suggest that NCGS may be a chronic disorder, as is the case with celiac disease.[71]

Besides gluten, additional components present in wheat, rye, barley, oats, and their derivatives, including other proteins called amylase-trypsin inhibitors (ATIs) and short-chain

TLR4)-mediated intestinal inflammation in humans.[73][74]

Wheat allergy

Main article: Wheat allergy

People can also experience adverse effects of wheat as result of a wheat allergy.[57] As with most allergies, a wheat allergy causes the immune system to respond abnormally to a component of wheat that it treats as a threatening foreign body. This immune response is often time-limited and does not cause lasting harm to body tissues.[75] Wheat allergy and celiac disease are different disorders.[57][76] Gastrointestinal symptoms of wheat allergy are similar to those of celiac disease and non-celiac gluten sensitivity, but there is a different interval between exposure to wheat and onset of symptoms. An allergic reaction to wheat has a fast onset (from minutes to hours) after the consumption of food containing wheat and could include anaphylaxis.[54]

Gluten ataxia

A male with gluten ataxia: previous situation and evolution after three months of gluten-free diet

Gluten ataxia is an autoimmune disease triggered by the ingestion of gluten.[77] With gluten ataxia, damage takes place in the cerebellum, the balance center of the brain that controls coordination and complex movements like walking, speaking and swallowing, with loss of Purkinje cells. People with gluten ataxia usually present gait abnormality or incoordination and tremor of the upper limbs. Gaze-evoked nystagmus and other ocular signs of cerebellar dysfunction are common. Myoclonus, palatal tremor, and opsoclonus-myoclonus may also appear.[78]

Early diagnosis and treatment with a

neurons in the cerebellum as a result of gluten exposure is irreversible.[78][79]

Gluten ataxia accounts for 40% of ataxias of unknown origin and 15% of all ataxias.[78][80] Less than 10% of people with gluten ataxia present any gastrointestinal symptom, yet about 40% have intestinal damage.[78]

Other neurological disorders

In addition to gluten ataxia, gluten sensitivity can cause a wide spectrum of neurological disorders, which develop with or without the presence of digestive symptoms or intestinal damage.[14] These include peripheral neuropathy, epilepsy, headache, encephalopathy, vascular dementia, and various movement disorders (restless legs syndrome, chorea, parkinsonism, Tourette syndrome, palatal tremor, myoclonus, dystonia, opsoclonus myoclonus syndrome, paroxysms, dyskinesia, myorhythmia, myokymia).[14][81]

The diagnosis of underlying gluten sensitivity is complicated and delayed when there are no digestive symptoms. People who do experience gastrointestinal problems are more likely to receive a correct diagnosis and treatment. A strict gluten-free diet is the first-line treatment, which should be started as soon as possible. It is effective in most of these disorders. When dementia has progressed to an advanced degree, the diet has no beneficial effect. Cortical myoclonus appears to be treatment-resistant on both gluten-free diet and immunosuppression.[14]

Labeling

People with gluten-related disorders have to remove gluten from their diet strictly, so they need clear labeling rules.[82] The term "gluten-free" is generally used to indicate a supposed harmless level of gluten rather than a complete absence.[83] The exact level at which gluten is harmless is uncertain and controversial. A 2008 systematic review tentatively concluded that consumption of less than 10 mg of gluten per day is unlikely to cause intestinal damage in people with celiac disease, although it noted that few reliable studies had been done.[83] Regulation of the label "gluten-free" varies.[82]

International standards

The

gluten-free". It only applies to foods that would normally contain gluten.[84]

Brazil

By law in Brazil, all food products must display labels clearly indicating whether or not they contain gluten.[85]

Canada

Labels for all food products sold in Canada must clearly identify the presence of gluten if it is present at a level greater than 20 parts per million.[86]

European Union & United Kingdom

In the European Union, all prepackaged foods and non-prepacked foods from a restaurant, take-out food wrapped just before sale, or unpackaged food served in institutions must be identified if gluten-free.[87] "Gluten-free" is defined as 20 parts per million of gluten or less and "very low gluten" is 100 parts per million of gluten or less; only foods with cereal ingredients processed to remove gluten can claim "very low gluten" on labels.[87] It is not allowed to label food as "gluten-free" when all similar food is naturally gluten-free, such as in the case of milk.[88]

All foods containing gluten as an ingredient must be labelled accordingly as gluten is defined as one of the 14 recognised EU allergens.[89]

United States

In the United States, gluten is not listed on labels unless added as a standalone ingredient. Wheat or other allergens are listed after the ingredient line. The

US Food and Drug Administration (FDA) has historically classified gluten as "generally recognized as safe" (GRAS). In August 2013, the FDA issued a final ruling, effective August 2014, that defined the term "gluten-free" for voluntary use in the labeling of foods as meaning that the amount of gluten contained in the food is below 20 parts per million.[90]

See also

References

  1. ^ Hervé This, « Who discovered the gluten and who discovered its production by lixiviation? », Notes Académiques de l'Académie d'Agriculture de France/Academic Notes from the French Academy of Agriculture, vol. 3, no 3, 2002, p. 1–11 (PMID 11911770, PMCID 1692935, DOI 10.1098/rstb.2001.1024).
  2. ^ a b Food and Drug Administration (January 2007). "Food Labeling; Gluten-Free Labeling of Foods" (PDF). Food and Drug Administration. Archived from the original (PDF) on 2007-01-26.
  3. ^
    PMID 28244676
    . Similar proteins to the gliadin found in wheat exist as secalin in rye, hordein in barley, and avenins in oats, and are collectively referred to as 'gluten'. The gluten found in all of these grains has been identified as the component capable of triggering the immune-mediated disorder, celiac disease.
  4. ^
    PMID 11911770
    .
  5. ^ "Gluten's role in bread baking performance". Canadian Grain Commission. 29 March 2016.
  6. PMID 24481131
    . the distinctive feature that makes wheat unique is, precisely, the visco-elasticity of gluten. When the grain is milled and mixed with water, storage proteins form a dough, capable of retaining gas bubbles. These properties make wheat suitable for the preparation of a great diversity of food products
  7. ^
    doi:10.1016/j.tifs.2005.10.003
    . Given the unique properties of wheat gluten, it is not surprising that it has been the subject of intense attention by the food industry. (...) Gluten does have economic benefits over and above the more expensive milk- or soy-protein products (Table 1), and its functional properties, which other products cannot duplicate, give it a unique place among the various protein products. (...) Unlike whey and soy proteins, gluten or wheat proteins are not high in biological value and have not been widely researched for nutritional advantages.
  8. ISBN 9783709169896
    .
  9. S2CID 211034183
    .
  10. ISBN 978-0-08-100529-3
    .
  11. ^
    S2CID 24533103
    .
  12. ^
    PMID 24667093
    .
  13. ^
    PMID 22345659
    .
  14. ^
    PMID 30806821
    .
  15. ^ Woychick, JH; et al. "The Gluten Proteins and Deamidated Soluble Wheat Protein". Archived from the original on 12 August 2009. Retrieved 8 September 2009.
  16. doi:10.1016/S0308-8146(96)00216-6
    .
  17. doi:10.1006/jcrs.1996.0094
    .
  18. doi:10.1094/CCHEM.2003.80.6.755
    .
  19. S2CID 24914227
    .
  20. ^ a b "Baking Technology, Bread". Bakersassist. Archived from the original on 2007-08-23. Retrieved 2007-08-14.
  21. ^ "Farinograph". Wheat Quality and Carbohydrate Research. North Dakota State University. 22 September 2014. Archived from the original on 23 December 2014. Retrieved 8 December 2014.
  22. doi:10.1016/S0733-5210(09)80058-1
    .
  23. ^
    PMID 25477689
    .
  24. ^ Amendola, J.; Rees, N.; Lundberg, D. E. (2002). Understanding Baking.
  25. ^ Eckhardt, L.W.; Butts, D.C. (1997). Rustic European Breads from your Bread Machine.
  26. ^ "Against the Grain". The New Yorker. 3 November 2014. Retrieved 8 December 2014.
  27. ISBN 978-0-913990-95-7
    .
  28. ^ Abramowski, Nicole (11 March 2011). "How to Make Seitan: An Illustrated Guide". Vegan Nom Noms. Retrieved 8 December 2014.
  29. ^ "Pet Foods". International Wheat Gluten Association. Archived from the original on 2007-10-07. Retrieved 14 August 2007.
  30. PMID 16436335
    .
  31. ^
    PMID 29531885
    .
  32. PMID 17021129
    .
  33. ^
    PMID 23293929.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  34. PMID 23083984
    .
  35. ^
    PMID 19355902
    .
  36. ^
    PMID 26217073.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  37. ^
    PMID 21248165
    . There are at least 50 toxic epitopes in gluten peptides exerting cytotoxic, immunomodulatory, and gut-permeating activities.
  38. ^
    S2CID 205094729
    . Previous studies have shown that gliadin can cause an immediate and transient increase in gut permeability. This permeating effect is secondary to the binding of specific undigestible gliadin fragments to the CXCR3 chemokine receptor with subsequent release of zonulin, a modulator of intercellular tight junctions. This process takes place in all individuals who ingest gluten. For the majority, these events do not lead to abnormal consequences. However, these same events can lead to an inflammatory process in genetically predisposed individuals when the immunologic surveillance system mistakenly recognizes gluten as a pathogen.
  39. PMID 24253052
    .
  40. ^
    PMID 27446824
    .
  41. PMID 26557006
    . It is necessary to consider that oats include many varieties, containing various amino acid sequences and showing different immunoreactivities associated with toxic prolamins. As a result, several studies have shown that the immunogenicity of oats varies depending on the cultivar consumed. Thus, it is essential to thoroughly study the variety of oats used in a food ingredient before including it in a gluten-free diet.
  42. ^
    PMID 25789300
    .
  43. ^
    PMID 26060103
    .
  44. PMID 22313950. Open access icon
  45. PMID 23934026
    .
  46. PMID 25662287
    . The increase in world-wide consumption of a Mediterranean diet, which includes a wide range of wheat-based foods, has possibly contributed to an alarming rise in the incidence of wheat (gluten?)-related disorders.1, 2
  47. ^
    PMID 23934026
    . mechanization of farming and the growing industrial use of pesticides have favored the development of new types of wheat with a higher amount of toxic gluten peptides that cause the development of gluten-related disorders
  48. PMID 17008163
    .
  49. S2CID 46259398
    .
  50. S2CID 220469138
    .
  51. ^
    PMID 31331324
    .
  52. ^ a b "Celiac disease". World Gastroenterology Organisation Global Guidelines. July 2016. Retrieved 23 April 2017.
  53. ^
    PMID 25922674
    .
  54. ^
    PMID 23252527
    .
  55. PMID 24834157
    .
  56. ^
    PMID 15825129
    .
  57. ^
    PMID 26109797
    .
  58. ^
    PMID 26438584
    .
  59. ^
    S2CID 24533103
    .
  60. S2CID 2023530
    .
  61. PMID 26825414
    .
  62. S2CID 9277897
    .
  63. PMID 24369326
    .
  64. ^
    PMID 24077239
    .
  65. ^
    PMID 25583468
    .
  66. PMID 25245857
    .
  67. PMID 29142467
    .
  68. ^
    PMID 19455131
    .
  69. ^
    S2CID 22521576
    .
  70. PMID 26060112
    .
  71. ^
    PMID 30711208
    . Furthermore, a role for the FODMAP (eg, fructans) component of wheat as the sole trigger for symptoms is somewhat doubtful, because many patients with NCWS report resolution of symptoms after the withdrawal of wheat and related cereals, while continuing to ingest vegetables and fruits with high FODMAP content in their diets.59 On the whole, it is conceivable that more than one culprit may be involved in symptoms of NCWS (as they are currently defined), including gluten, other wheat proteins, and FODMAPs.60–62
  72. PMID 29337156
    . Although intolerance to fructans and other FODMAPs may contribute to NCGS, they may only explain gastrointestinal symptoms and not the extraintestinal symptoms observed in NCGS patients, such as neurologic dysfunction, psychological disturbances, fibromyalgia, and skin rash.15 Therefore, it is unlikely that they are the sole cause of NCGS.
  73. PMID 25387079
    .
  74. PMID 23209313
    .
  75. ^ "What's the difference between celiac disease, gluten intolerance, non-celiac gluten sensitivity and wheat allergy?". The University of Chicago Celiac Disease Center. 2015. Retrieved 4 January 2015.
  76. ^ "Food intolerance and coeliac disease" (PDF). Food Standards Agency. September 2006. Archived from the original (PDF) on 15 October 2012. Retrieved 8 September 2009.
  77. PMID 22313950
    .
  78. ^
    S2CID 207673823
    .
  79. PMID 25823827
    .
  80. PMID 12566288
    .
  81. PMID 30096784
    .
  82. ^
    PMID 22649917
    .
  83. ^
    S2CID 20539463
    .
  84. ^ "Codex Standard For "Gluten-Free Foods" CODEX STAN 118-1981" (PDF). Codex Alimentarius. February 22, 2006.
  85. Anvisa. July 2014. Archived from the original
    on 2007-12-06. Retrieved 2014-07-22.
  86. ^ "Health Canada's Position on Gluten-Free Claims". Health Canada. 29 June 2012. Retrieved 28 January 2015.
  87. ^ a b "Labelling of 'gluten free' foods" (PDF). Food Standards Agency. 31 October 2016.
  88. ^ Food Safety Authority of Ireland https://www.fsai.ie/publications_GN24_glutenfree/. Retrieved 20 February 2023. {{cite web}}: Missing or empty |title= (help)
  89. ^ "EU Food Information for Consumers Regulation (EU FIC)" (link). Food Standards Agency. March 2016.
  90. ^ "Questions and Answers: Gluten-Free Food Labeling Final Rule". US Food and Drug Administration. 5 August 2014. Retrieved 4 January 2015.

Further reading

Retrieved from "https://en.wikipedia.org/w/index.php?title=Gluten&oldid=1215640512"
This page is based on the copyrighted Wikipedia article: Gluten. Articles is available under the CC BY-SA 3.0 license; additional terms may apply.Privacy Policy