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Coeliac Disease Guide

Feb. 2, 2021

Coeliac Disease Guide

Unfortunately, there is a lot of eye-rolling when people announce they are on a gluten-free diet, probably because there is an awful lot of confusion and misunderstanding between coeliac disease, food allergies, intolerances, and those on low carb diets by choice. With coeliac disease affecting about 70, 000 Kiwis, (1/80 are affected here, more than the 1/100 in other Western countries) it is important to understand it to support those around you who must live with this disorder lifelong. It is also estimated that 57,000 New Zealanders have coeliac disease but do not know it yet so it is well worth finding more out about it just in case your health and wellbeing and therefore your quality of life can be improved.

Coeliac disease is a condition in which those who have it become sensitive to gluten, a protein found in the cereals, wheat, rye, and barley. It is cured by having a diet without any gluten in, but this must be maintained for life. It is impossible to "outgrow" coeliac disease.

Gluten is turned into gliadin by enzymes in our digestive system. When a person who is genetically predisposed to coeliac disease, and has been triggered to develop it eats gluten, the body's immune system identifies the gliadin as toxic and overreacts.

What causes Coeliac Disease?

In 1944 Holland Dr Willem Dicke noticed that children with coeliac disease improved during the famine when there were wheat shortages. Coeliac disease is an autoimmune disorder; autoimmune disorders occur when the immune system malfunctions and attacks the body's own tissues and organs. It may cause a wide variety of signs and symptoms but is mostly considered as a disease of the gut. It is underdiagnosed and there are many individuals out there who do not yet know they have it, some of them with no symptoms.

Coeliac disease can develop at any age after an individual starts eating foods containing gluten. It used to be thought of as a disease that was diagnosed in childhood – in the past when testing options were less advanced only the very severe cases were picked up. Nowadays as testing has become far more advanced and less invasive, we realise that it was far more common than thought. It happens more frequently in women than men and is most frequently diagnosed in adults.

Coeliac disease runs in families and to get it you must carry certain genes, the Human Leukocyte Antigen genes (HLA) DQ2 and or DQ8. About 50% of people carry those genes. HLA genes are linked to many autoimmune diseases, not just coeliac disease. Those who have coeliac disease commonly have other autoimmune disorders. Everyone inherits a copy of the HLA genes from each parent. These copies can come in different versions called alleles. The HLA gene alleles that predispose a person to coeliac disease are called DQ2 and DQ8. An individual may have DQ2 or DQ8 in one of the copies or in both. People who have only one copy of DQ2 or DQ8 have a risk of about 3% of having coeliac disease, whereas people who have two copies of either have a risk of 10%. HLA types are combinations of genes, so it is possible to be DQ2 positive even if neither of your parents has this gene. At least 50% of children of parents carrying DQ2 or DQ8 will also have one of these.

As stated, having those genes does not mean you will go onto develop coeliac, only about one in 70 with the genes does. Why some are triggered to get it at some point in their lives has been a mystery, which up until recently was hypothesised to be due to stress, infections, and antibiotics. Some research out of Melbourne recently published in Nature Structural and Molecular Biology suggests that exposure to a bacterium that mimics gluten can confuse the immune system and trigger coeliac disease. This is the first time that the microbiome (the bugs that live in the gut) has been shown to be involved in the initiation of this disease. The microbiome is being recognised increasingly as being important in many conditions, and no doubt the research being done on it is going to answer many health questions in the future. What we do not yet understand is why some people with the predisposing genes and this type of bacteria are fine and others react. The study also perhaps explains the link with recent antibiotic use triggering coeliac disease, as antibiotics alter the microbiome (another reason not to use antibiotics unless necessary).

What is happening in the gut?

The classic symptoms of the condition result from inflammation affecting the gastrointestinal tract. This inflammation damages the villi, which are multiple small, finger-like projections that line the small intestine and provide a greatly increased surface area to absorb nutrients. In coeliac disease, they become "atrophied" which means they become shrunken and eventually flatten out. This damage to villi causes diarrhoea and poor absorption of nutrients, which may lead to weight loss. Abdominal pain, bloating, and food intolerances are common in coeliac disease. Lactose intolerance (an intolerance of some dairy products such as milk) often develops as the villi begin to atrophy, as the enzyme that breaks lactose down is stored at the ends of villi. This condition is usually reversed when the villi recover. Inflammation associated with coeliac disease may lead to an increased risk of developing certain gastrointestinal cancers such as cancers of the small intestine or oesophagus.

Inflammation and poor nutrient absorption may lead to problems affecting many other organs and systems of the body in affected individuals. Many people with coeliac disease have one or more of these varied health problems but do not have gastrointestinal symptoms. This form of the condition is called non-classic coeliac disease. Researchers now believe that non-classic coeliac disease is more common than the classic form.


Coeliac disease often goes undiagnosed because many of its signs and symptoms are nonspecific, which means they may occur in many disorders. Most people who have one or more of these nonspecific health problems do not have coeliac disease. On average, a diagnosis of coeliac disease is not made until 6 to 10 years after symptoms begin. Often the symptoms are put down to irritable bowel syndrome (IBS) as there is much cross over in terms of bowel symptoms.

Some people have no symptoms of the disorder. However, people with silent coeliac disease do have immune proteins in their blood (antibodies) that are common in coeliac disease. They also have inflammatory damage to their small intestine that can be detected with a biopsy.


The signs and symptoms of coeliac disease can vary greatly and differ in children and adults.

Digestive Symptoms for Adults includes

However, more than half the adults with coeliac disease have signs and symptoms unrelated to the digestive system.

Non digestive symptoms for adults include

Children with coeliac disease are more likely than adults to have digestive problems.

Children's digestive symptoms

The inability to absorb nutrients might result in:

Dermatitis herpetiformis

Gluten intolerance can cause this itchy, blistering skin disease. The rash usually occurs on the elbows, knees, torso, scalp, and buttocks. This condition is often associated with changes to the lining of the small intestine identical to those of coeliac disease, but the skin condition might not cause digestive symptoms.

Doctors treat dermatitis herpetiformis with a gluten-free diet or medication, or both, to control the rash.

How do the other wheat-related conditions compare?

A wheat allergy is not the same thing as coeliac disease. Someone who has an allergy to wheat will get swelling of their mouth, a rash and possibly struggle to breathe if exposed to wheat. It can be life-threatening to be exposed to wheat for these people, who also need to be on strict wheat-free diets. Someone who is gluten intolerant finds that they digest food more comfortably if they do not eat wheat, and perhaps get bloating and diarrhoea if they eat it, but without the damage to their bowel if they do. Many people are cutting carbs as part of a lifestyle choice, and they will not be harmed if they eat wheat. Fortunately, the growing number of people on wheat-free diets has increased the range of food options available in mainstream supermarkets, however, it has been a double-edged sword for coeliacs and those with wheat allergies who are often wrongly assumed just to be on a fussy fad diet.

Testing for Coeliac Disease

Testing is recommended for all symptomatic children and adults as well as asymptomatic people at increased risk.

People at increased risk include

Antibody tests are less reliable for excluding coeliac disease in very young children. Where there is strong clinical suspicion of coeliac disease and negative antibody tests it is recommended that the child be referred for specialist opinion. In New Zealand, screening of asymptomatic people is not recommended.

Blood tests for antibodies are the most useful preliminary step for testing symptomatic people and those with an increased risk of coeliac disease. People must have consumed adequate amounts of gluten (equivalent to four slices of bread daily) for 4–6 weeks prior to testing. Negative results cannot exclude coeliac disease if the patient has had a significantly reduced gluten intake. IT IS IMPORTANT THAT YOU DO NOT GO ON A GLUTEN FREE DIET PRIOR TO SEEING YOUR GP FOR TESTING, OTHERWISE YOU MAY GET A FALSE NEGATIVE TEST.

Antibody test - IgA tissue transglutaminase antibodies (TTG)

This is the preferred initial test for detecting coeliac disease. The TTG test detects IgA antibodies; consequently, tests can be negative in patients with coeliac disease with a coexisting IgA deficiency (more common in people with coeliac disease). To detect IgA deficiency, laboratories routinely test for total serum IgA whenever a TTG test is requested. If an IgA deficiency is detected, the IgG TTG test is performed. The antibodies increase in response to wheat exposure and decrease on a wheat free diet, so the test can also be used to assess how well a coeliac patient is doing with their diet.

Genetic testing also has a place – especially in young children. For genetic testing, the patient does not have to be consuming gluten prior to the test.

Genetic testing - HLA typing (HLA-DQ2 and DQ8)

Virtually all patients with coeliac disease are either HLA DQ2 or DQ8 positive, compared with 20–30% of the general population. In the rare circumstances that serological testing is equivocal, the absence of these HLA haplotypes can help exclude the diagnosis of coeliac disease.

Who requires biopsy?

Biopsy of the small intestine is recommended to confirm the diagnosis of coeliac disease. Serological testing may not correlate with mucosal damage and it is important to determine the degree of inflammation and villous atrophy in the gut as well as excluding other small bowel disease. A biopsy test may be appropriate if there is strong clinical suspicion, even if the TTG antibody test is negative. Serological testing may not be accurate in children under 5 years of age. A biopsy is done during a procedure called a gastroscopy usually performed by a gastroenterologist. A fibre optic camera is passed down either through the nose or mouth, down the oesophagus, through the stomach and into the small intestine. Biopsies can be taken and sent to a pathologist to analyse.


A gluten free diet is required lifelong. Most coeliacs feel better very quickly after going gluten free, but some take months or years to start improving. It takes considerable effort and will power to cut out all gluten – it is hidden in many foods where you would least suspect it. Gluten is in 80% of food stuffs and is also found in other products like medicine, cosmetics, play dough and toothpaste. One of the real problems for coeliacs is that they need to be aware that foods that were previously safe for them can be reformulated or are now made in a factory that also processes wheat products.

Even very small amounts of gluten, even 50mg per day (as much flour as you can fit under your little fingernail) can trigger intestinal damage. A few crumbs of bread can make all the difference. Therefore, those with coeliacs need a dedicated wheat free toaster and can not eat fries cooked in a frier that has cooked battered foods like fish or nuggets. Whilst some cafes and restaurants offer gluten free foods, if they use the same chopping boards, utensils, or grills to prepare them, the food easily becomes contaminated and unsafe.

Coeliacs should have support from a dietician to educate and support them if possible. They also need at least annual review to check on their symptoms. A year after their initial diagnosis they need a follow up gastroscopy to ensure they have reversed the villous damage. Children in particular need regular review to check on growth. Your doctor will perform blood tests to ensure there is adequate absorption of nutrients and may suggest a bone density scan.

There are some great resources and support from Coeliac New Zealand, This organisation does a great job educating and advising about coeliacs. It is worth joining if you or a family member have coeliacs. They run a Dining Out Programme for caterers, and once accredited with this, coeliacs know that they are safe places to eat out. They also accredit gluten free foods.

What does the future hold for coeliacs?

One of the most advanced drug developments for Coeliacs is from North Carolina, from 9 Meters Biopharma. The company is named after the length of the average gastrointestinal tract. Their drug, larazotide, is the first coeliac drug to enter phase 111 trials (in the days of Covid vaccine research this is something far more of us are familiar with). Larazotide hopes to reduce the leakiness in the junctions between cells that appear when a coeliac patient ingests gluten. This stops gliadin from entering the circulation and leading to the damaging autoimmune response. This is only an adjunct to a gluten free diet but will help those who struggle to strictly adhere to the diet and to prevent inadvertent exposure. Whilst 9 Meters Biopharma hopes to have a drug available by 2023 there are a few hurdles yet to overcome, and no doubt Pharmac will struggle to fund it.

There is much other research underway on how to improve the health of those with coeliac disease. Hopefully, the future will be much brighter for coeliacs.

What do I put on the table?

So, you have a friend coming over for dinner and you know they have coeliac. Do not panic, it is easy. They will really appreciate you taking the time and effort of making them food, too often they cannot participate safely in meals with friends. Do allow them to check out with you that the meal is safe, as they may have had bad experiences in the past.

Do not feel you have to go buying gluten free alternatives. Cook from scratch and use unprocessed fruit, vegetables, meat, fish, eggs, rice, and dairy. Do not use stock cubes, oats, malt products or soy sauce. Check the ingredients of any sauce or additional ingredients you use, it will normally say if it contains gluten, or has been produced in a factory producing gluten and if so, do not use it. If something says it is gluten free it is safe. Read all the labels! Some rice crackers are fine, others are not. Chocolate is almost all contaminated other than that made by a few smaller manufacturers. Lots of nuts and rice are processed in factories that also process wheat so be careful.

Gluten free beer is not easy to come by (Scotts Brewery is the first producer of gluten free beer in NZ), but wines and spirits, even those distilled from grains are ok unless they have flavourings added. Most soft drinks are fine.

If you do buy gluten free bread, cut it, and keep it completely separately from other bread. Do not let crumbs of bread get into your butter or spreads. Do not use the same oil to fry something that has already had a wheat product fried in it.

Some ice creams are gluten free, others not. Obviously do not serve ice cream in a cone.

Gluten Free Eating for Life

There are heaps of lovely gluten free recipes available, and almost each week the range of gluten free products in the supermarket increases. There are a few restaurants and cafes that go out of their way to be coeliac friendly. Others claim to have gluten free products, but staff are often unaware of the measures they need to take to avoid cross contamination, especially in some of the fast-food chains. Look out for the Dinning Out Programme accreditation and encourage participation in this scheme run by Coeliac New Zealand.

Good news spreads fast and the internet is a source of all useful information and blogs and some terrible ones. The Healthy Food Guide is a trustworthy source of information and worth a subscription.