How to test for gluten intolerance

What is gluten

Grains such as wheat, barley and rye contain a naturally occurring protein called gluten. Many foods like bread, pasta, pizza and most baked goods contain gluten. Gluten serves as a binder in foods, essentially holding them together. Think of the stretchy consistency of pizza dough or the springy bounce of a loaf of bread : that is all thanks to gluten! 

Baking would look very different without gluten. In fact, nowadays chefs and bakers around the world have mastered the art of gluten-free baking due to the rise in demand for gluten-free options. 

We mostly associate gluten with wheat, however other grains such as spelt, semolina and farro contain gluten. Oats are naturally gluten-free, however cross-contamination can lead to traces of gluten in oats. In fact, oats often grow near or are processed in the same facilities as other gluten-containing grains.(1)

Gluten intolerance vs celiac disease

Gluten intolerance is also referred to as non-celiac gluten sensitivity or gluten sensitive enteropathy (GSE). Intolerance to gluten occurs when you have similar symptoms as seen in celiac disease. However, on a physiological level the two conditions manifest differently. In fact, celiac disease involves intestinal damage and an attack from the immune system leading to high levels of antibodies.(2)

Moreover, celiac disease is a genetic disease. In fact, it tends to run in families so it is an inherited autoimmune disease. This condition is life-long and treatment involves following a strict gluten-free diet. Celiac disease takes place when the body reacts to gluten as a toxin, and immune cells overreact and attack it.

If a person has celiac disease and is unaware of it and keeps eating gluten, this can lead to inflammation and a range of undesirable symptoms. In fact, celiac disease typically manifests through gastrointestinal symptoms such as diarrhoea, steatorrhea and weight loss due to malabsorption of nutrients. Some people do not present any symptoms or may present extraintestinal symptoms (i.e. symptoms outside of the gut). These can include anaemia, osteoporosis and even neurological complications. Moreover, celiac disease is one of the most common genetic diseases affecting people worldwide. In fact, its prevalence is believed to be about 1% of the population.(3)

Similarly to celiac disease, gluten intolerance manifests through GI symptoms such as bloating, gas, diarrhoea or constipation. However it is not an autoimmune response and the body does not attack the intestine like in celiac disease. This is what makes an intolerance different from an autoimmune condition, even though the symptoms appear very similar. This is also why it is harder to diagnose gluten intolerance. In fact, there is no specific blood test to identify gluten intolerance. 

What about wheat allergy?

Wheat allergy is an allergy to one or more of the proteins found in wheat. One of these proteins is gluten, however there are others including: albumin, gliadin and globulin. Health professionals can diagnose wheat allergy via blood tests and a food challenge. These are carried out by allergists and specialised allergy dietitians respectively. Wheat allergy is different to celiac disease, which is a specific response to gluten only. In fact, the symptoms of wheat allergy can include hives, itchy eyes, swelling of the mouth, cramps and in the most severe cases, anaphylaxis. It is most often seen in children who fortunately outgrow the condition by adulthood in most cases. Moreover, people who test negative to wheat allergy may still have gluten sensitivity. Therefore, it’s important to investigate all symptoms and potential causes.(4)

How to test for gluten intolerance?

Unlike celiac disease which can be identified through a blood test, there is no diagnostic test for gluten intolerance. However, with the help of your doctor you can identify it by tracking persistent symptoms and by ruling out celiac disease. This can be done via a negative diagnostic celiac test. 

Some people may notice a pattern of symptoms which look like celiac disease but fail to test positive to celiac disease. This could be a sign of gluten intolerance. However, it is not recommended to self-diagnose gluten sensitivity or eliminate gluten without consulting with your dietitian or doctor first. In fact, eliminating gluten will not benefit your health unless you are intolerant to it. 

How to test for celiac disease?

Testing for celiac disease is something that you should discuss with your doctor. Routine testing is not recommended unless you have symptoms of the disease or you are at increased risk of developing them. For example, if you have a first degree relative with the condition such as a parent, sibling or child, you may be at increased risk. Moreover, some symptoms in children and adults warrant testing. These include persistent unexplained gastrointestinal symptoms such as being sick, weight loss, mouth ulcers, type 1 diabetes and unexplained iron deficiency anaemia. 

Testing involves having blood tests to identify whether or not you may have the condition, followed by a biopsy to confirm the diagnosis. During the testing process, you will need to consume gluten containing foods to ensure that the test results are accurate.In fact, avoiding gluten prior to your blood test could lead to an inaccurate result. In addition, you should not self-administer a gluten-free diet until the diagnosis of celiac disease is confirmed, even if your blood tests results are positive. If your blood tests show celiac disease antibodies, your doctor will refer you to get a biopsy for your gut cells.  

A biopsy is carried out by a gastroenterologist who will examine the lining of your gut via endoscopy. This involves inserting a very small tube with a light and camera at the end into your mouth and passed down into your intestine. Your doctor will provide a local anaesthetic and the option of a sedative to help you stay calm throughout the procedure and ease any nerves. Your doctor will take a small sample of the lining of your small intestine which they will subsequently examine under a microscope for signs of celiac disease.(5) 

Should I avoid gluten?

Many people believe that gluten is “unhealthy” and that eating gluten-free is healthier. Unless you have a diagnosed condition such as gluten intolerance or celiac disease, there is actually no reason to avoid gluten in your diet. However, it is a widespread belief that avoiding gluten may resolve stomach and digestive issues. In fact, a recent study found that people with irritable bowel syndrome (IBS) are more likely to avoid gluten than people without IBS. However there is a lack of clear scientific evidence to determine the appropriate guidelines for IBS, and excluding food groups as a result of self-diagnosis can lead to potentially detrimental effects.(6)

In fact, one study of almost 200 000 people without celiac disease found that gluten avoidance is associated with an increased risk of developing type 2 diabetes. This is likely because individuals who avoid gluten are also avoiding cereal fibres and other nutrients which contribute to good health. Moreover, people without celiac disease who cut out gluten have less diverse gut bacteria and can become more sensitive to gluten-containing foods over time.(7)

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