Coeliac disease

Sounds like 'see-lee-ak'

Coeliac disease is a permanent autoimmune disorder that causes a reaction to gluten, which is found in wheat, barley, rye and oats. This immune reaction makes part of your gut inflamed and can lead to a range of symptoms and nutritional problems.

Coeliac disease affects at least 1 person in 70, although perhaps as many as 4 out of 5 people who have the condition don’t know they have it.

What is gluten?

Gluten is a protein that is found in many grains such as wheat, barley, oats and rye. These grains are often used to make breads, pasta and cereals. Because many corn and rice products are produced in factories that also manufacture wheat products, they can also be contaminated with wheat gluten.

Hidden sources of gluten include additives such as modified food starch, preservatives and stabilisers made with wheat.

Gluten may also be found in everyday products such as medicines, vitamins and lip balms.

What causes coeliac disease?

Coeliac disease is caused by an abnormal reaction by your immune system to the protein gluten.

  • Your immune system mistakes gluten as a threat to the body and, in an attempt to protect the body from the threat, the immune system creates special gluten-fighting antibodies to fight it.
  • In the gut, these antibodies cause inflammation and flattening of the tiny, finger-like projections called villi which line the inside of the small bowel. The villi are responsible for the absorption of nutrients and minerals from food.
  • In coeliac disease, damage of the villi can lead to nutritional deficiencies (low levels) of iron, folic acid and calcium.

If undiagnosed, the condition can cause long-term poor health and other less common effects such as:

  • osteoporosis (due to reduced dietary calcium absorption)
  • iron deficiency anaemia
  • infertility
  • miscarriages
  • depression
  • dental enamel defects
  • increased chance of cancers of the oesophagus and gastrointestinal tract.

It is important to see your doctor if you suspect you may have the condition.

Who gets coeliac disease?

Coeliac disease can develop at any stage in life, from infancy to old age. It occurs in family groups and has a strong genetic tendency.

  • Around 10% (1 in every 10) of all first-degree relatives (parents, brothers, sisters or children) of people with coeliac disease also have the condition.
  • If one identical twin is affected, the other twin is almost certain to be affected.

Environmental factors are also believed to play a role in the development of the condition, although the exact nature of these remains unclear.

What are the symptoms of coeliac disease?

The symptoms of coeliac disease are different for everyone, depending on the person's age and degree of damage to the bowel. They can be similar to those of several other conditions, such as irritable bowel syndrome, which can complicate diagnosis.

In adults, common symptoms include:

  • diarrhoea: this may begin at any age and is often present for years prior to diagnosis. It may first appear after other illnesses (e.g. gastroenteritis) or following significant health events such as surgery, or pregnancy and childbirth
  • tiredness, weakness and lack of energy
  • weight loss
  • constipation (some are more likely to experience constipation rather than diarrhoea)
  • flatulence (wind, gas) and abdominal tightness
  • cramping and bloating
  • nausea and vomiting.

Anaemia is also more common in people with coeliac disease, particularly anaemia due to iron or folic acid deficiency. The anaemia will either not respond to treatment, or will recur after treatment until the underlying cause (i.e. coeliac disease) is identified and treated.

Less commonly, adults may experience:

  • easy bruising of the skin
  • ulcerations and/or swelling of mouth and tongue
  • miscarriages and infertility
  • low blood calcium levels with muscle spasms
  • vitamin B12, A, D, E and K deficiencies
  • skin rashes such as dermatitis herpetiformis
  • altered mental alertness
  • bone and joint pains.

Symptoms in children

In children, symptoms do not appear until gluten-containing foods are introduced into the diet. It is also possible for symptoms to appear later. The common symptoms include:

  • large, bulky, foul-smelling bowel movements (poo, stool)
  • diarrhoea or constipation
  • poor weight gain
  • weight loss in older children
  • iron deficiency anaemia
  • stunted growth
  • bloated tummy, pain and flatulence
  • nausea and vomiting
  • irritability.

How is coeliac disease diagnosed?

Because the symptoms of coeliac disease are similar to those of many other gastrointestinal diseases, the diagnosis of coeliac disease can be challenging. It is usually diagnosed with blood tests, bowel biopsy and gene test. It is important to keep eating gluten until after diagnosis. If the gluten-free diet is started before diagnosis, this may affect the accuracy of investigations such as blood tests and biopsies.

Feeling better on a gluten-free diet is not enough to confirm the diagnosis of coeliac disease.


Diagnostic tests for coeliac disease

Blood tests
  • A range of blood tests that measure antibodies to gluten are a useful way of identifying those who might need further tests.
Bowel biopsy
  • The only way of knowing for certain if someone has coeliac disease is by showing that the lining of the small bowel is damaged. 
  • This is done performing a bowel biopsy, a procedure in which a tiny sample of the bowel lining taken for analysis.
  • If a diagnosis of coeliac disease is made, the small bowel biopsy will sometimes need repeating at some point after starting a gluten-free diet, to check that the bowel lining is recovering.
Gene test
  • A gene test is available which can help identify people who may be at risk of developing the condition, but on its own is not sufficient to confirm the diagnosis.
  • This test is most helpful when it is negative, because in this situation it is 99% certain that a person will not develop coeliac disease.

How is coeliac disease treated?

There is no known cure for coeliac disease. The only treatment is following a gluten-free diet, which will allow most people to return to normal health.

  • A gluten-free diet means a lifelong, no-exceptions diet, leaving out all foods containing wheat, rye, barley, triticale and oats. Oats can cause a reaction in some people with the condition, and are not safe to include in the diet even if labelled as ‘gluten-free oats’.
  • Children and younger people recover quite quickly after adopting a gluten-free diet (usually within 6 months), but older people may take longer to recover.
  • Sometimes nutrients such as iron, folic acid and some vitamins may need to be replaced at the start of treatment.
  • In addition, it is sometimes beneficial to reduce cow’s milk in the diet at first, to allow the bowel to replenish its levels of the enzyme lactase that aids its digestion.

People with coeliac disease remain sensitive to gluten throughout their life. If gluten remains in the diet, damage to the small bowel will still be happening, even if symptoms disappear.

Associated autoimmune conditions

People with coeliac disease are genetically predisposed to developing some other autoimmune conditions, or already have these conditions when they are diagnosed with coeliac disease. This is because it is likely there is a common gene link between these conditions. These include:

  • thyroid disease (causing either an underactive or an overactive thyroid)
  • Addison’s disease
  • autoimmune liver disease
  • sarcoidosis
  • Sjogren’s syndrome
  • type 1 diabetes.

Therefore if you have coeliac disease, talk to your GP about whether you have the symptoms of any of these conditions, particularly thyroid disease, as this is the most common.


For more information, contact Coeliac New Zealand, a support group for adults and children with coeliac disease.

  • Membership benefits include a regular magazine, along with telephone support and assistance.  
  • New members are provided with a manual containing information on the condition, the gluten free diet, where to shop, recipes and helpful advice to make the change from gluten to gluten-free as easy as possible. 

Learn more

What is coeliac disease? Coeliac New Zealand
Coeliac disease overview University of Chicago Celiac disease center (USA)

Credits: Health Navigator Editorial Team. Reviewed By: Dr Derek JY Luo, MBChB (Otago) FRACP, Consultant Gastroenterologist Last reviewed: 23 Sep 2016