What is coeliac disease, wheat allergies and gluten intolerance?

Find out about how gluten is involved in coeliac disease and wheat allergies and their differences.
Published 9 October 2021

What is gluten?

Gluten is a protein found in certain cereal grains including wheat, rye, barley and oats. Gluten is also added to some foods as a stabilising agent. In cooking, gluten helps baked goods, such as bread, to rise and gives them their fluffy texture.

There are several medical conditions that may require a gluten-free diet. The main ones are coeliac disease, wheat allergy and gluten intolerance/ sensitivity.

What is coeliac disease?

Coeliac disease is a permanent abnormal immune reaction to gluten, often called an auto-immune disease. In people with coeliac disease, gluten reacts with the lining of the small intestine and causes damage by inflaming the tiny projections called villi that help us digest food. This damage reduces the small intestine’s ability to absorb nutrients from food.

Symptoms of coeliac disease include tiredness, iron deficiency, weight loss, bone and joint pains, mouth ulcers, altered mental alertness, skin rashes and easy bruising of the skin. If undiagnosed, coeliac disease can lead to other medical problems such as early-onset osteoporosis and infertility. People diagnosed with coeliac disease need to follow a gluten-free diet and require ongoing care from a gastroenterologist.

How is coeliac disease diagnosed?

  • Blood tests to measure the presence of antibodies to gluten and determine the need for a biopsy. Genetic tests are also available to determine disease susceptibility and may aid diagnosis.
  • Small-bowel gastroscopy and biopsy by a gastroenterologist to assess whether the small bowel lining is damaged.

What is a wheat allergy?

Along with milk, peanuts, eggs and shellfish, wheat allergy is one of the common food allergies. An allergy is an immune response in which the body produces antibodies to attack substances that are harmless to most people. Eating (or sometimes even touching) these substances can trigger an allergic inflammation that causes symptoms such as itching, burning and swelling of the mouth, wheezing and breathing difficulties, skin rash, hives, vomiting and nausea. In some cases, wheat allergy can cause anaphylactic shock, which can be life-threatening. Wheat allergy is often diagnosed in children, but can also appear in adulthood. People diagnosed with a wheat allergy require ongoing care from an immunologist.

How is wheat allergy diagnosed?

  • Skin-prick tests by an immunologist to measure blood-antibody levels to allergens.

What is gluten intolerance/sensitivity?

Unlike coeliac disease, food intolerance is not an immune response but a chemical reaction experienced after consuming certain foods and drinks. However, a gluten intolerance can still have a major impact on your general wellbeing, with common complaints including abdominal pain, diarrhoea, bloating and excessive wind, as well as extreme tiredness, poor concentration and general aches and pains.

Non-coeliac gluten sensitivity is the term used to describe symptoms attributed to dietary gluten, but its cause and treatment is not well understood. Research indicates gluten might not be the problem, and that malabsorption of fermentable sugars (known as FODMAPs) may be the culprit in those with irritable bowel syndrome. If this is the case, it is often only wheat and a range of other foods – not gluten in general – that you need to limit.

It can be tempting to self-diagnose gluten intolerance, but it’s important to consult a health professional to ensure serious medical conditions are not present and that your diet does not become unbalanced by excluding gluten-containing foods.

How is non-coeliac gluten sensitivity diagnosed?

  • Health-professional consultation to exclude coeliac disease, wheat allergy or other medical conditions.
  • Irritable bowel syndrome is assessed in conjunction with a gastroenterologist and an accredited practising dietitian.

Is giving up gluten healthier?

Some people believe that following a gluten-free diet or buying gluten-free foods means they are being healthier. However, this is certainly not always the case, and deciding to stop eating foods containing gluten requires a careful balancing act to ensure your nutrient requirements are met.

In fact, it’s much trickier to diagnose problems if you make the switch to gluten-free before seeing a health professional. Be patient, as you generally need to still be consuming foods containing gluten for tests to be effective. If a gluten-free diet has already been adopted, some of the tests used to diagnose coeliac disease may produce false negatives.