Gluten intolerance or sensitivity

Also known as non-coeliac gluten sensitivity (NCGS)

Gluten intolerance is used to describe gut and other symptoms that appear to be caused by eating gluten, but are not as a result of coeliac disease.

Key points

  1. It’s common to experience a range of symptoms that could potentially be caused by eating gluten – from abdominal pain, bloating and loose stools to lethargy, headaches and general muscle and joint aches.
  2. However, these symptoms can be caused by many things, so it’s important to see a doctor before diagnosing gluten as the cause.
  3. Removing gluten from your diet without medical advice puts you at risk of missing out on some nutrients, and this can lead to other health issues.
  4. Diagnosis of gluten intolerance is difficult as there is no test for this condition. However, getting the right diagnosis is your best chance of improving your symptoms and maintaining good health long term.

What causes non-coeliac gluten sensitivity (NCGS)?

Gluten is a protein found in wheat, rye, barley and oats. There are also a number of foods that contain ‘hidden’ gluten because these grains are one of the ingredients in them, such as sausages and stock powders.

Gluten intolerance or sensitivity is used to describe symptoms in response to eating gluten when these symptoms are not caused by the autoimmune condition coeliac disease.

There is little research into this condition, so the causes are not known. There is also debate as to whether the symptoms may be those of irritable bowel syndrome (IBS) in response to eating foods that contain FODMAPs. 

FODMAPs are a group of foods that can cause your bowel to stretch and expand. This leads to similar symptoms as those for gluten intolerance or sensitivity. Read more about FODMAPs.

What are the symptoms of NCGS?

Whatever the cause is, the symptoms are real and can cause a lot of discomfort and pain. They include gut or digestive symptoms, as well as other symptoms. They include:

  • abdominal (tummy) pain
  • bloating
  • diarrohea (runny poos)
  • lethargy
  • headaches
  • general muscle and joint aches.

The symptoms occur in a few hours or days after you have eaten gluten, improve rapidly when you stop eating gluten and come back soon after eating gluten again.

How is NCGS diagnosed?

Gluten intolerance symptoms are similar to those of other medical conditions, so you need to see your doctor for a diagnosis rather than diagnosing yourself.

They will ask you questions about your symptoms and may examine your abdominal (tummy) area. In order to rule out coeliac disease, they will probably ask you to do a screening blood test.

Removing the main sources of gluten may remove symptoms, but if you have coeliac disease, you will still do damage to your bowel if you eat small amounts of gluten or are exposed to it through cross-contamination of gluten-free food with gluten-containing ingredients.

If a diagnosis of coeliac disease has been excluded, there may still be other causes for your symptoms when you eat gluten. For example, your doctor will want to work out whether your symptoms only occur with wheat-containing foods (which would mean you could eat the other gluten-containing grains: rye, barley and oats).

Your doctor will also want to consider whether your symptoms might be caused by irritable bowel syndrome.

Once you have an accurate diagnosis, your doctor will be able to provide you with advice as to the most appropriate dietary changes.

How is NCGS treated?

Many people cut gluten from their diet because they think they are intolerant to it. But because it's hard to know whether the symptoms are due to an intolerance to gluten, an intolerance to something else in wheat, or some other reason, see your doctor for an accurate diagnosis to prevent unnecessary avoidance of gluten. Your doctor can make a referral to a dietitian to help you make decisions about your diet.

Very few people need to cut out gluten from their diet (although it's important to do so if you have coeliac disease). However, if your doctor thinks this is the best approach for you, a dietitian can teach you how to replace the nutrients you will miss out on with a gluten-free diet. Read more about the gluten-free diet.

Should I try a gluten-free diet to see if it gets rid of my symptoms?

You should not put yourself on a gluten-free diet. This should only be done on the advice of a doctor, dietitian or registered nutritionist.

They will guide you on an elimination diet, where you avoid all suspect foods for a set time, then gradually reintroduce them to find which particular foods cause your symptoms to return. Keeping a food diary helps with this process.

Taking food groups from your diet can cause deficiencies in some nutrients, which may lead to other health problems in the longer term.

It has not been proven that gluten is responsible for symptoms such as bloating, and gluten-containing products (such as wheat bread) form an important part of the New Zealand diet. 

Isn’t a gluten-free diet healthier though?

No, a gluten-free diet is not healthier. Gluten-free products are often higher in fat and sugar to make them taste better. The gluten-free flours used in breads and pastas are often highly refined, low in fibre and have a high glycaemic index (GI) rating, meaning they aren’t very filling and don’t contain wholegrains, which are good for your health.

Gluten-free diets have been found to be lacking in fibre, calcium, iron and B vitamins. Also, gluten-free products are more expensive than the usual foods with gluten in them.

Unless you have been diagnosed with coeliac disease or dermatitis herpetiformis, there is no evidence suggesting health benefits from cutting out all gluten from your diet.

But I have tried a gluten-free diet and feel better – why?

People with gut symptoms such as abdominal pain, bloating, wind and diarrhoea often feel better on a gluten-free diet. As explained above, this may mean you have IBS.

Removing gluten from your diet may have also removed the irritant causing the symptoms, such as the FODMAP fructan, which is found wherever there is gluten. It is better to get help from a dietitian to work out which is causing your symptoms so you only remove the food you need to. 

What support is available with NCGS?

Coeliac NZ has extended its membership criteria to include people with NCGS. They provide information and support for anyone on a gluten-free diet.

Learn more

The following links provide further information about gluten intolerance. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

Non-coeliac gluten sensitivity Coeliac NZ
Coeliac disease vs. gluten intolerance (Dr Jason Tye-Din) Coeliac NZ
How do you eat gluten free? Coeliac NZ

References

  1. Gluten sensitivity Coeliac UK
  2. Food intolerance NHS, UK, 2019
  3. Gluten Nutrition Foundation, NZ, 2017
  4. Al-Toma A, Volta U, Auricchio R. European Society for the Study of Coeliac Disease (ESsCD) guideline for coeliac disease and other gluten-related disorders United European Gastroenterology Journal. 2019 Jun 1; 7(5):583-613.

Reviewed by

  Dr Derek Luo is a consultant gastroenterologist at Counties Manukau Health and has also been in private practice since 2011. He has a broad interest in general gastroenterology and hepatology and has a sub-specialty interest in pancreatic and hepatobiliary disease.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Derek Luo, consultant gastroenterologist at Counties Manukau Health Last reviewed: 14 Aug 2020