Coeliac disease vs gluten intolerance: A Mayo Clinic Healthcare gastroenterologist explains the difference

After suffering from asthma-like symptoms that caused difficulty breathing and impacted his ability to perform everyday activities, Gerard Kenneally was diagnosed with hypertrophic cardiomyopathy in Ireland. The drug treatment he'd been offered had been ineffective, so he sought further support from Mayo Clinic Healthcare in London.

A loaf of bread containing gluten.

With the growing availability of gluten-free food options, people may begin to question whether they should incorporate gluten into their diets or not. Dr Sarmed Sami, a gastroenterologist at Mayo Clinic Healthcare in London, explains why for most people there is no need to completely eliminate gluten from the diet, and the difference between two gluten-related medical conditions: coeliac disease and gluten intolerance.

Gluten is a protein found in grains such as wheat, barley and rye. For most people, there is no need to completely eliminate foods containing gluten and no proven benefit from doing so, says Dr Sami.

"There's no evidence that a gluten-free diet by itself is healthier," Dr Sami says. "It's not about the gluten. Take a biscuit, for example: It's more about the fat and the sugar in the biscuit, rather than the gluten."

However, there are certain gluten-related medical conditions in which eating gluten can lead to gastrointestinal symptoms: coeliac disease and gluten intolerance.

One sign that someone has gluten intolerance or coeliac disease is the presence of one or more gastrointestinal symptoms such as diarrhoea, bloating or heartburn that diminish or go away if gluten is removed from the diet and come back if the person resumes eating foods with gluten, Dr Sami says. If this happens, it is important to be tested in case it is the more serious coeliac disease, he adds.

In coeliac disease, eating gluten triggers an autoimmune reaction that causes cell damage to the small intestine. This in turn can cause diarrhoea, fatigue, weight loss, bloating, anaemia and other problems and can cause serious complications.

Gluten intolerance is more common, Dr Sami says. It is comparable to an intolerance to dairy, onions or garlic, he adds.

"In gluten intolerance, there is no cell damage or inflammation. It's more of a sensitivity: 'Gluten doesn't agree with me,'" Dr Sami says. "If you eat gluten and have an immediate reaction, such as diarrhoea, that's more likely to be gluten intolerance than coeliac disease, which is a slow process that you don't tend to feel immediately."

Addressing gluten intolerance may be as simple as cutting back on foods containing gluten rather than eliminating them completely, Dr Sami says.

"It depends on the intolerance level. Some people may be fine by halving the gluten intake, while others may need to cut down more," Dr Sami says. "It's different from coeliac disease, where you have to be strictly, completely, gluten-free."

There is no cure for coeliac disease and the cause is not entirely clear . For the majority of patients diagnosed with coeliac disease, eliminating gluten keeps it under control, Dr Sami says. But without a coeliac diagnosis, there is no reason to eliminate gluten.

In coeliac disease, the immune system misidentifies certain substances in gluten as a threat and responds by attacking them . Diagnosing coeliac disease typically starts with a blood test to determine whether the body views gluten as an invader and is generating high levels of antibodies to protect itself. If a blood test is positive, an imaging test called endoscopy is used to take biopsies to check for damage in the small intestine.

"We typically recommend that people should not be on a gluten-free diet if they are being tested for coeliac disease, because that can create false negative results on the blood test." Dr Sami says.

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