Gluten is a type of protein contained in rye, barley, and wheat. Some cereals, bread, and beer contain rye. Malt-containing foods and beer often include barley, and wheat is a grain often used in making pasta, cereals, and bread.
Wheat or gluten can trigger gastrointestinal discomfort or other symptoms in susceptible individuals. There are various conditions linked to gluten intolerance, such as wheat allergy, coeliac disease, and non-coeliac gluten sensitivity.
Wheat allergy is an immune-mediated reaction to any of the proteins (including gluten) found in wheat and is most prevalent in children. Allergy to other grains may or may not be present. Symptoms can range from mild to life-threatening. Onset is typically within minutes of consumption up until two hours afterward.
Symptoms can consist of:
- Nausea and vomiting
- Nasal congestion
- Ocular irritation
- Mouth/throat irritation
- Breathing difficulty
Wheat allergy may be diagnosed by a skin-prick test or blood test. The skin-prick test involves the introduction of a wheat protein-containing liquid into the skin. Development of a raised, red spot may indicate an allergy. Alternatively, a blood test can be used to screen for the presence of immunoglobulin E antibodies to wheat protein.
Coeliac disease is an autoimmune disorder whereby the immune system reacts to gluten. Inflammation of the intestinal mucosa and destruction of the villi in the small intestine are the results. This can lead to severe health problems such as permanent intestinal harm. Such damage to the villi can also cause malnutrition secondary to malabsorption.
Both adults and children can develop coeliac disease. It is difficult to detect coeliac disease in adults, as presenting symptoms are frequently quite varied and can be similar to a variety of other chronic complaints. Patients may not have any symptoms at all, ranging to the presentation of severe symptoms. Damage to the villi can still, unfortunately, eventuate regardless of symptom severity.
Adults may experience digestive symptoms, but are more commonly found to present with:
- Iron deficiency anaemia
- Weight loss or gain
- Changed mental acuity
- Bone and joint pain
- Easy bruising
- Frequent miscarriage or infertility
- Missed menstrual periods
- Tingling sensation in the hands/feet
- Recurring mouth ulcers
- Swelling of tongue or mouth
Children often present with digestive symptoms such as:
- Stomach pain
- Nausea and vomiting
- Chronic diarrhoea
- Abdominal bloating and flatulence
Malabsorption during a child’s phase of growth and development can lead to future health issues such as:
- Reduced height
- Dental enamel deficiencies
- Weight loss
- Delayed puberty
- Failure to thrive (in infants)
Coeliac disease can be screened for via a blood test that detects autoantibodies produced as part of an inappropriate immune response to gluten. It is important that a gluten-free diet is not commenced before testing as a false negative result can occur. If gluten has been eliminated from the diet, then normal eating patterns must recommence for a minimum of six weeks before testing, whereby at least four slices of wheat bread must be eaten daily for adults (or two slices for children) to ensure sufficient exposure to gluten. A small bowel biopsy is recommended following a positive blood test to verify the diagnosis. This sample is assessed for atrophy to the villi and inflammation of the underlying mucosal tissue.
Gene testing can be helpful for people with an unclear diagnosis. This may occur due to difficulty in interpreting blood test or biopsy results, or if gluten intake was insufficient to render the test results reliable. The HLA DQ2 or HLA DQ8 genes, or parts of these genes are present in more than 99% of people with coeliac disease. However, only one in 30 people with the HLA DQ2 or HLA DQ8 genes will develop coeliac disease. Therefore, a negative gene test virtually eliminates the possibility of coeliac disease. The gene test is not reliant upon the patient consuming gluten-containing foods in the lead up to testing, and so can be undertaken regardless of diet. However, if the gene test is positive, then a gluten dietary challenge followed by a small bowel biopsy will be required to investigate for coeliac disease. People with unexplained infertility, a family history of coeliac disease, autoimmune disease, liver disease, or early osteoporosis should undergo screening for coeliac disease.
Treatment of coeliac disease is a strict gluten-free diet. Maintenance of such a diet can result in symptoms resolving, healing of the small intestine, and a decreased risk of long-term health compromise.
Non-Coeliac Gluten Sensitivity
Evidence is emerging for a condition in people without coeliac disease or wheat allergy that results in symptoms. This condition has been termed non-coeliac gluten sensitivity (NCGS). As yet, the precise cause is unknown. There is no diagnostic test for this condition, and so after testing negative for coeliac disease and wheat allergy, patients may be asked to maintain a symptom diary to establish whether gluten is triggering symptoms. Patients will then be asked to commence a gluten-free diet once the cause is verified. The severity of symptoms and a patient’s own ability to cope with a gluten-free diet will dictate the strictness of maintaining the diet. Some studies question the pathogenesis of this condition. A 2013 study suggested that fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) may be responsible for symptoms in some patients who fulfil the criteria for NCGS.
Today there are a variety of wheat-free and gluten-free foods available as alternatives to pasta, cereals, bread, etc. However, it is important to be aware that wheat and gluten can be found in some medications and vitamin supplements and foodstuffs such as ice cream, sauces, and syrup. Therefore, people with an intolerance to wheat or gluten need to be vigilant in reading food and drink labels to ensure they do not include wheat or gluten. The Therapeutic Goods Administration (TGA) requires that all pharmaceutical labels must state the inclusion of any ingredients from an “allergenic source” which includes gluten. People requiring a gluten-free diet can eat naturally gluten free food such as fresh meats, fresh fruits and vegetables, nuts, legumes, milk, eggs, fats and oils. There are also some naturally gluten-free grains and seeds that may be consumed as an alternative to wheat including rice, millet, sorghum, quinoa, and corn. The Australia New Zealand Food Standard’s Code require all foods labelled as ‘gluten-free’ to not contain any detectable gluten. The code also requires all gluten-containing cereals to be declared on the label. Gluten-free products may also be readily identified by the Coeliac Australia Endorsement Logo. Products containing this logo have been tested to be appropriate for those with coeliac disease; and gluten free by ingredient. A person with gluten intolerance can therefore still enjoy a variety of foods and maintain a healthy, balanced diet.
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