Understanding coeliac disease



Coeliac disease is an autoimmune condition in which eating gluten causes the immune system to attack and damage the small intestine.

Gluten is a protein found in wheat, rye and barley. In people with coeliac disease, even very small amounts of gluten can trigger an immune response that damages the small intestine.

In Australia and New Zealand, oats are not permitted in foods labelled gluten free, as oats can trigger symptoms or immune responses in a subset of people with coeliac disease and cannot be reliably considered safe for everyone.

For this reason, a strict, lifelong gluten free diet, as defined by Australian standards, is essential for managing coeliac disease and preventing ongoing intestinal damage and long-term complications.

There is currently no cure for coeliac disease. It does not resolve over time, but it can be effectively managed through strict gluten avoidance.

This page focuses on building a clear, practical understanding of coeliac disease – what it is (and what it isnโ€™t), why there is no safe level of gluten exposure, and how it differs from other gluten-related conditions.

For diagnosis, treatment, and individual medical advice, always rely on medically qualified health professionals.


WHY THERE IS NO SAFE LEVEL OF GLUTEN

In coeliac disease, gluten exposure triggers an immune response that damages the lining of the small intestine. This damage can occur even without obvious symptoms, which means someone may feel well while still experiencing ongoing intestinal damage.

This immune response means that:

  • Small or repeated exposures can cause harm
  • Symptoms are not a reliable indicator of safety
  • Strict, consistent gluten avoidance is required

This is what distinguishes coeliac disease from conditions where gluten avoidance is based on symptom management alone.

โ†’ Read: Everyday gluten free living


REFRACTORY COELIAC DISEASE

In rare cases, some people with coeliac disease continue to experience intestinal damage and symptoms despite strict, long-term adherence to a gluten free diet. This is known as refractory coeliac disease.

Refractory coeliac disease is rare and affects a very small proportion of people with coeliac disease. It is uncommon and is only diagnosed after careful assessment by specialists. Before this diagnosis is considered, other causes of ongoing symptoms or intestinal damage must be excluded, including:

  • accidental or hidden gluten exposure
  • slow or incomplete intestinal healing
  • other gastrointestinal conditions
  • nutrient deficiencies or related autoimmune conditions

Refractory coeliac disease is not caused by poor compliance with the gluten free diet. It reflects a more complex immune response that requires specialist investigation and management, usually under the care of a gastroenterologist with experience in coeliac disease.

Anyone with ongoing symptoms, abnormal blood results, or evidence of persistent intestinal damage despite a strict gluten free diet should be reviewed by their medical team.

The following resources provide additional information from reputable medical and coeliac organisations:


COELIAC DISEASE & NON-COELIAC GLUTEN SENSITIVITY (NCGS)

Coeliac disease is not a food allergy or intolerance. It is an autoimmune condition with measurable intestinal damage and immune markers.

Non-coeliac gluten sensitivity (NCGS) describes people who experience symptoms when consuming gluten but do not have coeliac disease and do not show the same immune-mediated intestinal damage.

Key differences include:

  • Coeliac disease causes autoimmune intestinal damage
  • NCGS does not cause the same intestinal damage
  • Coeliac disease requires lifelong strict gluten avoidance for medical reasons
  • NCGS management is based on symptom response rather than immune damage

Correct diagnosis is important, as management and long-term health considerations differ.

The following resources provide additional information from reputable Australian and New Zealand health and coeliac organisations:

โ†’ Read: Newly diagnosed with coeliac disease


TOPICAL GLUTEN & CONTACT REACTIONS

For people with coeliac disease, gluten causes harm when it is ingested, not through skin contact alone. Topical products such as makeup, moisturisers, shampoos and hair products do not trigger the autoimmune intestinal response unless gluten is swallowed.

Some people experience contact reactions, skin irritation, or other symptoms when using products that contain gluten or gluten-derived ingredients. These reactions are not a coeliac disease response, but may be related to:

  • Skin sensitivity or contact dermatitis
  • Allergic reactions
  • Other individual sensitivities

Products applied near the mouth, such as lipsticks, lip balms, or hand products, may appear to pose a higher risk of accidental ingestion, which is why some people with coeliac disease choose to avoid gluten-containing products in these situations.

However, the amount of gluten present in cosmetics is typically very very small. Coeliac Australia has advised that a person would need to consume an unrealistically large amount of a product, such as an entire tube of lipstick in a single day, to reach the minimum amount of gluten known to trigger a coeliac reaction. This makes routine use of most cosmetic and topical products very low risk for people with coeliac disease.

If someone experiences reactions to topical products, this should be treated as a separate issue and discussed with an appropriate health professional. It does not indicate that gluten is being absorbed through the skin or causing the autoimmune response seen in coeliac disease.

For more information about gluten in cosmetics, personal care, and topical products, see:

โ†’ Read: Everyday gluten free living


GLUTEN IN MEDICINES AND SUPPLEMENTS

Medicines and supplements are regulated differently from food and require separate consideration.

Learn more about how gluten is managed and labelled in medicines and supplements, and what this means for people with coeliac disease.

โ†’ Read: Gluten in medicines and supplements


HOW COELIAC DISEASE IS DIAGNOSED

Coeliac disease is diagnosed using a combination of blood tests (called a coeliac serology) and an upper endoscopy with biopsy.

Diagnosis must be made while a person is still consuming gluten, as testing relies on detecting the immune response triggered by gluten.

Doctors usually begin testing for coeliac disease using blood tests that look for antibodies produced by the immune system when gluten is consumed.

Common screening blood tests include:

  • tTG-IgA (tissue transglutaminase IgA) โ€“ the primary screening test
  • Total IgA level โ€“ used to check for IgA deficiency

In some cases, additional tests may be used, including:

  • DGP antibodies (deamidated gliadin peptide)
  • EMA antibodies (endomysial antibodies)

These tests look for signs that the immune system is reacting to gluten. However, blood tests alone cannot always confirm a diagnosis, and further testing is required by a gastroenterologist to check for internal damage.


IMPORTANT: TESTING MUST BE DONE WHILE EATING GLUTEN

Testing for coeliac disease is the most accurate when a person is still eating gluten regularly.

Blood tests and biopsies rely on detecting the immune response triggered by gluten. If gluten is reduced or removed from the diet before testing, this immune response can decrease or disappear, which may lead to false-negative results.

For this reason, it is important to continue eating gluten until testing has been completed, unless advised otherwise by a healthcare professional.


WHAT IS A GLUTEN CHALLENGE?

If someone has already reduced or removed gluten from their diet before testing, a gluten challenge may be recommended.

A gluten challenge involves reintroducing gluten for a period of time so that blood tests and biopsies can detect the immune response associated with coeliac disease.

That is:

  • consuming gluten daily for around 6 weeks
  • roughly the equivalent of 4 slices of wheat-based bread per day

The exact amount and duration should always be discussed with a specialist before beginning a gluten challenge.


GENETICS & WHAT TRIGGERS COELIAC DISEASE

Coeliac disease develops through a combination of genetic susceptibility and environmental factors. Most people with coeliac disease carry specific immune system genes, but many people who carry these genes never develop the condition.

Learn more about the genes associated with coeliac disease and the environmental factors researchers believe may influence whether the disease develops.

โ†’ Read: Genetics and what triggers coeliac disease


TRUSTED INFORMATION ON COELIAC DISEASE

The following resources provide clear, evidence-based information on coeliac disease and gluten exposure:


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