Gluten 101

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Thank you to Student Dietitian Marcos Gregoriou for writing this blog post about gluten, the gluten-free diet and the risks related to unnecessarily avoiding gluten.


What is Gluten?

Gluten is made up of plant storage proteins known as gliadin and glutenin found in wheat grain.  A specific sequence of amino acids which are the building blocks of proteins, are present in gliadin and other plant storage proteins like secalin (found in rye) and hordein (in barley) have been recognised as triggering Coeliac Disease (CD) (1). Similar protein is found in oats called avenin. However, this is considered unharmful in most people with CD (2).

Gluten and Food Production

Gluten is an important constituent in baking and food production. It offers stability and elasticity in the dough during bread baking which allows it to rise and hold its shape. Gluten also gives pasta and cookies the desired quality e.g. hard texture and crumbliness respectively (3). 

Coeliac Disease

CD is not an allergy nor an intolerance, it is an autoimmune inflammatory disease which means the body mistakenly causes damage to its cells when gluten is ingested (2).  The damage occurs at the walls of the small intestine causing inflammation as the digested gluten makes its way there (4). Inflammation decreases the ability of the villi (finger-like projections in the intestines) to absorb nutrients and minerals, this is known as nutrient malabsorption (5).

Those who have a clinical diagnosis of CD must follow a gluten-free diet for life, as there is no cure for CD (5). 

Symptoms

Common symptoms of CD include (6): 

  • Diarrhoea 
  • Bloating 
  • Indigestion
  • Stomach pain
  • Constipation

However, CD can occur with no symptoms being present at all (7).

Untreated CD can cause also prolonged poor nutrient absorption which in turn can lead to:

  • Iron-deficiency anaemia 
  • Osteoporosis
  • Intestinal cancer (although this is fortunately very rare) 

How Common is Coeliac Disease?

1% of the global population (8) and 1 in 100 people in the UK live with Coeliac Disease. However, it is estimated that 500,000 people remain undiagnosed in the UK. This may be related to the fact that symptoms don’t always occur, and CD can also be misdiagnosed with other conditions such as  IBS. 

There is also an issue with a late diagnosis which often doesn’t occur until a person is 13 years old, and occurs most often between the age of 40-60 years (as this age group are more likely to be undergoing investigations such as scopes and blood tests) (9). In recent years, increased awareness of CD and the use of less invasive testing methods have led to earlier diagnosis in children (10).

Diagnosis 

The first-line of diagnosis is a blood test to check for specific antibodies the body produces in response to gluten intake, this is known as the IgA-tTG test. For this to be accurate 3-6g of gluten (e.g. 4x slices of wheat bread) per day (11) needs to be consumed at least once a day 6 weeks before testing (5). 

Another blood test could be carried out known as the endomysial antibody (EMA) that is very specific to CD. 

Finally, the gold standard is to examine a tissue sample from the gut for intestinal damage, which is called an endoscopic intestinal biopsy (5).

Genetic testing is a way of excluding CD if the individual does not have the gene HLA-DQ2/8 which accounts for 99% of CD cases (12). Since CD is a genetic condition, it Is Important to mention that CD is more common in people who have other autoimmune diseases like Type-1 diabetes (and vice versa). There is also a 10% chance of having CD if a first-degree relative is Coeliac e.g. your parent, child, brother or sister (9).

Naturally Gluten-Free foods (9)

  • Fruit, vegetables, pulses and nuts
  • Milk and dairy
  • Potatoes and rice
  • Fresh meat
  • Fresh fish and shellfish
  • Fats and oils 

Only foods with gluten-free statements are safe for those with CD to eat under European Food labelling laws of 2014 (13).

Risk of Unnecessary Gluten Avoidance 

Currently, 3.7% of the UK population avoid gluten with only 0.8% being clinically diagnosed with CD (14).

Bread is a staple food in many countries, in the UK it is responsible for providing up to (15);

  • 12% of energy requirements 
  • 20% carbohydrate requirements 
  • 12% protein requirements 
  • 21% fibre requirements 

Bread is also low in saturated fat, sugars and since it is fortified it is a source of calcium, manganese and B vitamins (thiamine) (15). This is similar to cereals and cereal products as they are responsible for >40% of fibre intake in the UK among important minerals like iron and calcium (16). 

As gluten-containing food provides so many macronutrients and micronutrients in the UK diet, unnecessary avoidance without appropropriate support could cause dietary problems through possible deficiencies. Studies have also found that avoiding gluten can lead to a higher intake of fat and salt intake (17). 

Gluten-free diets have also been found to be more expensive than gluten-containing diets, For example, gluten-free bread can be 400% more expensive per 100g than gluten-containing bread (18). 

Non-Coeliac Gluten or Wheat Sensitivity (NCGS)

NCGS is a grey area where CD and wheat allergy have been ruled out, but similar symptoms to CD  occur in response to consuming gluten (19).  

However, this condition is poorly understood and there is a lot of academic debate and uncertainty surrounding NCGS.

Allergy UK states that “there is still a lot of controversy as to whether or not [NCGS] exists and whether it is caused by gluten or another protein found in wheat. It is unclear if it is an intolerance or whether the immune system is involved and it is also unclear if it is lifelong or whether it is a temporary condition” (20).

Conclusion 

Gluten is an important constituent in food production due to its structural properties. Foods containing gluten are rich in minerals and vitamins which are essential for a healthy diet. 

If you feel you have any symptoms of CD it is vital to visit your GP for an assessment. Once a diagnosis has been established or ruled out, a Dietitian can then support you with your dietary choices to ensure you maintain a balanced diet. Remember that gluten-free food does automatically make a food healthy, in fact important nutrients may be missing. 

Reference List

  1. Biesiekierski, J. (2017) “What is gluten?”, Journal of Gastroenterology and Hepatology, 32, pp. 78-81. doi: 10.1111/jgh.13703.
  2. Kennedy, K. (2019) Coeliac Disease. In: J. Gandy, ed. Manual of Dietetic Practice. 6th edn. Newark: Wiley-Blackwell, pp. 432-445.
  3. Delcour, J. et al. (2012) “Wheat Gluten Functionality as a Quality Determinant in Cereal-Based Food Products”, Annual Review of Food Science and Technology, 3(1), pp. 469-492. doi: 10.1146/annurev-food-022811-101303.
  4. Sturgess, R., Ellis, H. and Ciclitira, P. (1991) “Cereal chemistry, molecular biology, and toxicity in coeliac disease.”, Gut, 32(9), pp. 1055-1060. doi: 10.1136/gut.32.9.1055.
  5. National Institute for Health and Care Excellence (NICE) (2015) Coeliac Disease Recognition, Assessment and Management Clinical Guideline NG20. [pdf] s.l. National Institute for Health and Care Excellence. Available at: https://www.nice.org.uk/guidance/ng20/evidence/full-guidance-438530077 [Accessed: 23 October 2020]. 
  6. Aziz, I. and Sanders, D. (2014) “Coeliac disease and nutrition”, Advanced Nutrition and Dietetics in Gastroenterology, pp. 160-168. doi: 10.1002/9781118872796.ch3.11.
  7. British Society of Gastroenterology (BSG) (2014) BSG Guidelines on the Diagnosis and Management of Adult Coeliac Disease, The British Society of Gastroenterology. Available at: https://www.bsg.org.uk/clinical-resource/bsg-guidelines-on-the-diagnosis-and-management-of-adult-coeliac-disease/ [Accessed: 23 October  2020].
  8. Green, P. and Cellier, C. (2007) “Celiac Disease”, New England Journal of Medicine, 357(17), pp. 1731-1743. doi: 10.1056/nejmra071600.
  9. Coeliac UK (2019) Coeliac disease fact sheet 2019, Coeliac UK. Available at: https://www.coeliac.org.uk/document-library/6207-coeliac-disease-fact-sheet-2019/ (Accessed: 23 October 2020).
  10. Murch, S. et al. (2013) “Joint BSPGHAN and Coeliac UK guidelines for the diagnosis and management of coeliac disease in children”, Archives of Disease in Childhood, 98(10), pp. 806-811. doi: 10.1136/archdischild-2013-303996.
  11. Adriaanse, M. and Leffler, D. (2015) “Serum Markers in the Clinical Management of Celiac Disease”, Digestive Diseases, 33(2), pp. 236-243. doi: 10.1159/000371405.
  12. Abadie, V. et al. (2011) “Integration of Genetic and Immunological Insights into a Model of Celiac Disease Pathogenesis”, Annual Review of Immunology, 29(1), pp. 493-525. doi: 10.1146/annurev-immunol-040210-092915.
  13. Official Journal of European Union(OJEU) (2020) EUR-Lex – 32014R0828 – EN – EUR-Lex, Eur-lex.europa.eu. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32014R0828 (Accessed: 23 October 2020).
  14. Aziz, I. et al. (2014) “A UK study assessing the population prevalence of self-reported gluten sensitivity and referral characteristics to secondary care”, European Journal of Gastroenterology & Hepatology, 26(1), pp. 33-39. doi: 10.1097/01.meg.0000435546.87251.f7.
  15. Lockyer, S. and Spiro, A. (2020) “The role of bread in the UK diet: An update”, Nutrition Bulletin, 45(2), pp. 133-164. doi: 10.1111/nbu.12435.
  16. Roberts C, Steer T, Maplethorpe N et al  (2018) National Diet and Nutrition Survey Results from Years 7 and 8 (combined) of the Rolling Programme (2014/2015 to 2015/2016). London: PHE publications. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/699241/NDNS_results_years_7_and_8.pdf (Accessed: 23 October 2020).
  17. Niland, B. and Cash, B. (2018) “Health Benefits and Adverse Effects of a Gluten-Free Diet in Non–Celiac Disease Patients”, Gastroenterology Hepatology, 14(2), pp. 89-91. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5866307/ (Accessed: 23 October 2020).
  18. Hanci, O. and Jeanes, Y. (2018) “Are gluten-free food staples accessible to all patients with coeliac disease?”, Frontline Gastroenterology, 10(3), pp. 222-228. doi: 10.1136/flgastro-2018-101088.
  19. Fasano, A. et al. (2015) “Nonceliac Gluten Sensitivity”, Gastroenterology, 148(6), pp. 1195-1204. doi: 10.1053/j.gastro.2014.12.049.
  20. Allergy UK (2020) Types of Food Intolerance | Help and Advice | Allergy UK, Allergyuk.org. Available at: https://www.allergyuk.org/information-and-advice/conditions-and-symptoms/586-types-of-food-intolerance (Accessed: 23 October 2020).

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