I have just been diagnosed with gluten intolerance. Can you please explain the difference between gluten intolerance and coeliac disease?

The terms “gluten intolerance”, “wheat intolerance” and “gluten sensitivity” can be quite confusing. This problem arises because there are no widely accepted criteria doctors can use to define these problems. The causes, treatment and medical consequences of these conditions are not well understood and the role of a gluten free diet is even less clear. In contrast coeliac disease has very clear diagnostic criteria and there is good evidence that a strict life long gluten free diet is the only treatment to maintain health and avoid long term complications.

In general, gluten intolerance is associated with unpleasant symptoms after eating food containing gluten (whether that be from wheat, rye, barley or oats). Symptoms may include tummy upset (for instance diarrhea, bloating or crampy pain) and others such as fatigue, headache or irritability. People who are wheat intolerant may feel their problems relate specifically to wheat products and not other gluten containing grains such as rye or barley. In practice, it can be difficult to make this distinction. Some doctors use the term gluten sensitivity to describe people with medical symptoms (or conditions) that appear to worsen with gluten in the diet but the person does not fit all the criteria to make a definite diagnosis of coeliac disease (for instance the coeliac blood test or bowel biopsy is normal). Apart from helping to reduce symptoms, there is minimal evidence that a gluten free diet is beneficial to maintain long term health in this setting, and the decision to be on a gluten free diet needs to be made in consultation with your doctor.

In contrast to gluten intolerance, coeliac disease is a very important medical condition that can have a number of serious consequences if not diagnosed and treated properly. In coeliac disease the sufferer’s immune system reacts abnormally to gluten in the diet causing small bowel inflammation and damage and a variety of problems such as poor nutrient absorption, vitamin deficiencies (iron deficiency is very common) and thinning of the bones (osteoporosis). There is an increased risk of autoimmune disease (such as type 1 diabetes and thyroid disease) and certain forms of cancer such as lymphoma of the small bowel. Fortunately timely diagnosis of coeliac disease and treatment with a strict, lifelong gluten free diet can prevent or reverse many of these problems.

Therefore it is important that your doctor first determines whether your gluten intolerance symptoms could actually be caused by coeliac disease. A coeliac blood test should be used as the initial screening test (“coeliac serology”, the important one being the transglutaminase antibody), and if it is positive the diagnosis must be confirmed by performing a gastroscopy, a procedure that allows tiny samples (biopsies) to be taken from the small bowel which can reveal if gluten is causing damage. A gastroscopy takes about 10 minutes and is done in a hospital or day-procedure centre while the patient is sedated (most people find it very straight-forward). Taking small bowel biopsies is a vital part of diagnosing coeliac disease as the blood test alone is not definitive. If the biopsy reveals small bowel damage consistent with coeliac disease a strict gluten free diet and ongoing medical follow-up is the appropriate treatment. The doctor will perform other tests such as checking your nutrient levels and bone density and advise family screening.

If a diagnosis of coeliac disease has been excluded then there may be other causes for your symptoms when you eat gluten (or wheat) containing foods. This is an area of emerging interest and further research needs to be performed to understand the processes that are causing these symptoms. In some cases gluten may not be the only culprit; new evidence suggests other components of wheat (such as the sugar or carbohydrate portion) could contribute to wheat intolerance if the bowel has a problem absorbing fructose sugars (a condition called fructose malabsorption). This can be diagnosed by a hydrogen breath test and managed in consultation with a specialist dietitian. Irritable bowel syndrome is a common cause of tummy upset in the community and symptoms are occasionally triggered by specific dietary components. Each of these conditions have their own treatments which may be more appropriate than a gluten free diet.

Dr Jason Tye-Din

Consultant Gastroenterologist

The Royal Melbourne Hospital

NHMRC Postgraduate Research Fellow

The Walter and Eliza Hall Institute