Coeliac disease and gluten intolerance: what’s the difference?

Around one in ten Australians report following a gluten-free diet.

That involves avoiding everyday foods such as bread, pasta and noodles that contain gluten, a protein present chiefly in wheat, barley and rye.

Not everybody who eats gluten-free has a medical condition. However, nausea, bloating or stomach pain after eating gluten could indicate gluten intolerance or coeliac disease.

Although gluten intolerance and coeliac disease have many symptoms in common, one of them can result in damage to the intestine and malnutrition. So what distinguishes them?

What is coeliac disease?

Coeliac disease is an autoimmune condition. In other words, the body incorrectly attacks healthy cells and tissue - in this instance, within the small intestine - leading to inflammation.

It affects approximately one in 70 Australians, although only 20% of those affected receive a diagnosis.

For people with coeliac disease, consuming gluten-containing foods can harm the villi. These structures in the small intestine enable the body to take in nutrients.

After a gluten-containing meal, digestive symptoms may include diarrhoea, bloating, nausea, wind and abdominal pain.

Gluten may also bring on symptoms unrelated to digestion, including brain fog, headaches, dermatitis herpetiformis (an itchy, blistering skin rash), joint pain and tiredness.

Over time, untreated coeliac disease may cause malnutrition, as damaged villi cannot absorb nutrients from food. It may also lower bone mineral density and has been associated with neurological conditions including epilepsy and dementia.

How is coeliac disease diagnosed?

To obtain an accurate diagnosis, you must still be eating gluten. This allows its impact on your digestive system to be assessed.

Diagnosis involves blood tests, followed by small-intestine biopsies performed with an endoscope - a lit instrument used to view inside the body.

The blood tests check for antigens, which are markers of a reaction to gluten, while the biopsy examines the intestinal villi for damage.

In certain cases, doctors use capsule endoscopy. This involves swallowing a camera the size of a pill, which is used to inspect the intestine for signs of damage.

What about gluten intolerance?

Those with gluten intolerance can have symptoms resembling coeliac disease. However, eating gluten does not trigger an autoimmune reaction or damage the intestine.

Gluten intolerance is also sometimes called non-coeliac gluten sensitivity.

It is estimated that 1% of Australians have gluten intolerance, but just 12 in every 100 people in this group have been diagnosed by a doctor.

For someone whose symptoms are linked to eating gluten, doctors first exclude coeliac disease and wheat allergy.

After these conditions have been ruled out, they may advise a supervised gluten-free diet trial with an accredited practising dietitian to establish whether symptoms get better.

A definitive gluten intolerance diagnosis can only be made through a very complex dietary trial comparing the effects of gluten with a placebo over at least eight weeks.

This type of scientific research requires considerable labour and is uncommon.

As a result, many people decide to cut out gluten without receiving a diagnosis.

Extreme sensitivity to gluten

Coeliac disease is more serious than gluten intolerance, and sensitivity levels differ between people who have been diagnosed.

Symptoms can be brought on by even tiny traces of gluten. A strict gluten-free diet for life is therefore essential.

People with coeliac disease must also take care to avoid cross-contamination. For instance, using the same knife, chopping board or toaster for gluten-free bread and ordinary bread can pass on gluten particles and trigger a reaction.

The latest research indicates that consuming only 50mg of gluten daily can cause intestinal damage in people with coeliac disease.

To put this in perspective, one slice of wholewheat bread has roughly 4,800mg of gluten, so 50mg is about 1/100th of a slice.

A small quantity of gluten does not affect somebody with gluten intolerance in the same manner. They might experience temporary symptoms, but their intestine will not be damaged.

Nevertheless, both the symptoms and how severe they are differ from person to person according to individual sensitivity.

Should I cut out gluten, just in case?

You may be asking whether avoiding gluten has any drawbacks if you do not have coeliac disease or an intolerance.

It can.

Gluten-containing grain foods provide important nutrients, including fibre, folate, iron and B-group vitamins.

Avoiding gluten unnecessarily can result in nutritional deficiencies.

Gluten-free foods may also cost more, and sometimes contain more sugar, salt and fat to make up for differences in texture and flavour.

Before altering your diet, it is advisable to consult an accredited practising dietitian, who can help ensure you are not missing essential nutrients.

So, what if you have symptoms?

Typical symptoms of gluten intolerance or coeliac disease include bloating, diarrhoea or constipation, and stomach pain. Either condition may also cause non-gastrointestinal symptoms, such as headaches, fatigue and joint pain.

If this sounds familiar, speak with a health-care professional. They may test for coeliac disease and/or a wheat allergy before you remove gluten from your diet.

Keep in mind that diagnosing yourself and cutting out gluten without appropriate advice could cause more harm than good.

If you are worried about your symptoms, consult your GP, a gastroenterologist or a qualified dietitian. Dietitians Australia provides a list of accredited practising dietitians.

Yasmine Probst, Professor, School of Medical, Indigenous and Health Sciences, Advanced Accredited Practising Dietitian, University of Wollongong, and Olivia Wills, Associate Lecturer, Nutrition and Dietetics, University of Wollongong

This article is republished from The Conversation under a Creative Commons licence. Read the original article.