In focus: Coeliac Disease

What is coeliac disease?

Coeliac disease (CD) is an immune-mediated and inflammatory condition triggered by gluten causing the mucosa of the small intestine to attack and damage its tissues. The damage to the finger-like villi results in malabsorption of essential nutrients. Unlike a food intolerance or food allergy, the management of coeliac disease requires a life-long abstinence from gluten. Gluten is a protein found in wheat, barley, and rye typically found in pasta, breakfast cereals, breads, cakes, and biscuits. 

In the UK, approximately 1 in 100 people are affected by CD however, only 10-20% will have been diagnosed as having CD. Having a close family member (parent, sibling, child) with CD increases the risk by 10% although, it is still unknown why some individuals develop CD and others don’t. While CD is diagnosed more often in females and children, its incidence has been rising sharply across all ages in Western countries since the mid-1900s. More research is needed, particularly in Africa, Asia, and Latin America, to understand the full global picture [1]. Over the past 50 years, the prevalence of CD has risen partly due to screening people at high risk and the increased use of diagnostic tools [2].

What are the symptoms of coeliac disease?

The symptoms of CD are often described as classic or non-classic. Classic would involve diarrhoea, weight loss, malabsorption, deficiency in vitamins and minerals, stunted growth, and failure to thrive in children. Non-classic symptoms can affect an individual physically (on any area of the body such as the stomach, teeth, and skin) and emotionally (some may suffer from anxiety and depression thus likely leading to reduced energy levels and fatigue). The types of symptoms and the severity range differ between individuals, making it frustrating for sufferers. For example, some may think they have a wheat intolerance or irritable bowel syndrome due to stomach pains; for others, they do not have any symptoms, but the ingested gluten will still cause damage to the gut. Hence, monitoring symptoms is important until a medical diagnosis is made.

As CD is an autoimmune condition, people living with type 1 diabetes [3], autoimmune thyroid disease [4], Down’s syndrome [5], and Turner syndrome [6] are at a higher risk of developing the condition. There are likely many other autoimmune conditions not listed by NICE that may be linked to CD of which there is ongoing research to explore CD and other possible related conditions. Untreated and undiagnosed CD may lead to the development of osteoporosis and in some cases unexplained infertility [7].

How is coeliac disease diagnosed?

For an accurate diagnostic process, patients must follow a gluten-containing diet for six weeks (at least one meal daily) before a blood test at the GP. A gluten-free diet is not recommended until a diagnosis is confirmed by a gastroenterologist, even if the results are positive.

For suspected CD in young people and adults, NICE recommends [8]:

• Total immunoglobulin A (IgA) and IgA tissue transglutaminase (tTG) as the first choice

• IgA endomysial antibodies (EMAs) if IgA tTG is weakly positive

• Consider using IgG EMA, IgG deamidated forms of gliadin peptides (DGPs), or IgG tTG if IgA is deficient.

For children:

• Total IgA and IgA tTG as the first choice.

• Consider using IgG EMA, IgG DGP, or IgG tTG if IgA is deficient.

Some individuals may require further blood tests whereas others may need an endoscopy to confirm a diagnosis. However, in 2020, The British Society of Gastroenterology (BSG) issued interim guidance for the diagnosis of CD, supported by Coeliac Disease UK, which was to pause non-urgent endoscopies during the coronavirus pandemic [9]. Following the new guidelines means that the diagnosis of CD in adults can be made based on blood tests alone.

The no-biopsy criteria are for patients under 55 years of age with symptoms of CD and whom:

• Does not need an endoscopy to rule out other conditions

• Has IgA tTg at least 10 times the upper limit of normal

• Has a second positive antibody blood test (EMA or tTG if EMA isn't available)

The decision of a patient endoscopy with biopsy and the final diagnosis of CD sits with the gastroenterologist.

What is the dietary management of coeliac disease?

The only known effective treatment available for CD is a life-long adherence to a strictly gluten-free diet. A registered dietitian specialising in CD helps patients discover which foods are suitable based on personal preferences and how to read food labels to identify which to avoid. It can be overwhelming for patients receiving a CD diagnosis and making a drastic switch to a dietary approach that requires close monitoring to ensure there is no cross-contamination (for example, using the same knife that had been used to cut gluten-containing bread). A small percentage of individuals are sensitive to oats due to potential cross-contamination of wheat, rye, and barley so it’s important to recommend to these patients to eat gluten-free oats only. 

Gluten-free products are widely available in supermarkets and online retailers that commonly stock frozen, chiller food, and cupboard food items. The downside to gluten-free products is that they are often more expensive so the patient’s GP may be able to add the gluten-free food on prescription depending on availability. It is important to remember that many gluten-free products are also classified as ultra-processed foods. [10].

By UK law, foods labelled ‘gluten-free’ must not exceed 20 parts per million of gluten as this is the safe level for individuals living with CD. Some ingredients such as barley malt extract and codex / gluten-free wheat starch have had the gluten removed so if labelled ‘gluten-free,’ these would also be safe to consume. In addition, the trusted symbol of Coeliac UK’s crossed grain signifies which packaged foods are gluten-free. Independent manufacturing audits and gluten analysis certificates are the extra checks these certified products undergo to ensure people with CD can enjoy them safely on a gluten-free diet.

While a registered dietitian can offer ideas for eating out and at and away from home, it’s important to highlight that following a gluten-free diet can all add up. There are naturally gluten-free foods that are affordable on most budgets such as all varieties of vegetables and fruit, rice, potatoes, quinoa, millet, buckwheat, teff, amaranth, sorghum, dairy food and dairy alternatives, and protein-rich foods (pulses, beans, fish, meat, eggs, lentils, and nuts). Furthermore, a registered dietitian will ensure a healthy, balanced dietary intake. A systematic review and meta-analysis found that adults have an insufficient daily fibre intake (approximately 18.9g) and inadequate calcium, iron, magnesium, and vitamin D intake [11]. For some individuals suffering from constipation or low fibre intake, it’s important to encourage fibre as part of each meal and to enjoy it as a snack. For example, beans, pulses, nuts, seeds, and all types of fruits and vegetables.

Which resources are available?

There are national and local specialist coeliac support groups and registered dietitians with specialist knowledge of CD. Coeliac UK [12] is a leading charity that provides many resources and digital apps to help identify which foods are safe to eat in the supermarket.

References

[1] King JA, Jeong J, Underwood FE, Quan J, Panaccione N, Windsor JW, Coward S, deBruyn J, Ronksley PE, Shaheen AA, Quan H, Godley J, Veldhuyzen van Zanten S, Lebwohl B, Ng SC, Ludvigsson JF, Kaplan GG. Incidence of Celiac Disease Is Increasing Over Time: A Systematic Review and Meta-analysis. Am J Gastroenterol. 2020 Apr;115(4):507-525. doi: 10.14309/ajg.0000000000000523. PMID: 32022718.

[2] Patient. 2021. Coeliac disease: causes, symptoms and treatment. 

[3] Cohn A, Sofia AM, Kupfer SS. Type 1 diabetes and celiac disease: clinical overlap and new insights into disease pathogenesis. Curr Diab Rep. 2014 Aug;14(8):517. doi: 10.1007/s11892-014-0517-x. PMID: 24952108; PMCID: PMC4156157.

[4] Liu Y, Yao N, Wang Y, Dong Y, Wang L, Wang F, Wu Z, Wang S, Li B. The association of gluten-free diet with thyroid autoimmunity in patients with celiac disease: a meta-analysis. Food Funct. 2024 Feb 5;15(3):1089-1098. doi: 10.1039/d3fo01573d. PMID: 38205645.

[5] Carnicer J, Farré C, Varea V, Vilar P, Moreno J, Artigas J. Prevalence of coeliac disease in Down's syndrome. Eur J Gastroenterol Hepatol. 2001 Mar;13(3):263-7. doi: 10.1097/00042737-200103000-00008. PMID: 11293446.

[6] Al-Bluwi GSM, AlNababteh AH, Östlundh L, Al-Shamsi S, Al-Rifai RH. Prevalence of Celiac Disease in Patients With Turner Syndrome: Systematic Review and Meta-Analysis. Front Med (Lausanne). 2021 Jun 17;8:674896. doi: 10.3389/fmed.2021.674896. PMID: 34222285; PMCID: PMC8247446.

[7] Coeliac UK. Conditions linked to coeliac disease

[8] The National Institute for Health and Care Excellence (NICE). 2015. Coeliac disease: recognition, assessment and management. [NICE guideline No. 20]

[9] The British Society of Gastroenterology (BSG). 2020. BSG Interim Guidance: COVID-19 specific non-biopsy protocol for those with suspected coeliac disease.

[10] The British Nutrition Foundation (BNF). 2023. The concept of ultra-processed foods (UPF): Position statement April 2023

[11] Gessaroli M, Frazzoni L, Sikandar U, Bronzetti G, Pession A, Zagari RM, Fuccio L, Forchielli ML. Nutrient intakes in adult and pediatric coeliac disease patients on gluten-free diet: a systematic review and meta-analysis. Eur J Clin Nutr. 2023 Aug;77(8):784-793. doi: 10.1038/s41430-023-01280-0. Epub 2023 Mar 1. PMID: 36859658.

 [12] Coeliac UK