As sales of gluten-free products continue to rise, we separate the wheat from the chaff.
Many people are now opting for a gluten-free diet, despite not having been diagnosed as coeliac. But the idea of ‘gluten sensitivity’ is a relatively new concept.
We speak to Luisa Mearin, Secretary of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition, Henrietta Norton, Harley Street nutritional therapist and founder of Wild Nutrition and Charlene Grosse, accredited dietitian and spokesperson for the Dietitians Association of Australia, about the latest evidence in the area of gluten-related disorders:
What is gluten?
Gluten refers to a certain group of protein found in grains, most commonly wheat, rye and barley. ‘There is gluten in everyday foods like pasta and bread, as well as foods like couscous or gluten-containing flour,’ explains Norton.
‘Part of gluten is gliadin,’ she adds. ‘This is the part of the gluten that contains specific amino acid sequences. If you imagine gluten proteins to be like blocks of Lego, gliadin is the most common protein that people may be sensitive to – and can indeed be very damaging (and mortality increasing) for someone with coeliac disease. There are several forms of gliadin in wheat and when these forms are put together, they make up a group of storage proteins called prolamine.’
Gluten-related disorders is an umbrella term used for all diseases triggered by gluten. It includes the following:
➡️ Coeliac Disease
Coeliac disease is an autoimmune disorder that often runs in families. ‘It is caused by a reaction of the immune system to gluten – a protein found in wheat, barley and rye,’ explains Mearin. ‘When a person with coeliac disease eats gluten, his immune system reacts by damaging the lining of the small intestine.’
This damage then prevents nutrients from being absorbed into the body, leading to nutritional deficiencies and a number of related health problems and symptoms.
‘Coeliac disease may present with a large variety of nonspecific signs and symptoms,’ explains Mearin. ‘Some common symptoms include chronic or intermittent diarrhoea, growth problems, failure to thrive, weight loss, delayed puberty, amenorrhoea, iron-deficiency anaemia, nausea or vomiting, chronic abdominal pain, cramping or distension, chronic constipation, chronic fatigue, recurrent mouth ulcers, dermatitis herpetiformis–like rash, fracture within adequate traumas/osteopenia/osteoporosis and abnormal liver tests.’
Around one per cent of the population are thought to suffer from coeliac disease – and of those, nearly three-quarters remain undiagnosed. The only treatment for coeliac disease is a strict lifelong gluten-free diet.
➡️ Wheat allergy
If you have an allergy, you will have an immune reaction to wheat that occurs within minutes to hours after wheat exposure. Diagnosis is made through skin prick tests, wheat-specific IgE blood testing and a food challenge.
Wheat allergy is relatively rare and probably affects under one per cent of the population. Sufferers either need to follow a wheat-free or gluten-free diet, depending on the nature of the allergy.
What is non-coeliac gluten sensitivity?
Coeliac disease and wheat allergy have long been medically recognised, and have a very distinct diagnosis, but in recent years it has become acknowledged that an adverse reaction to gluten can also occur in individuals who don’t suffer from one of these conditions.
‘In 2011, gastroenterologists gathered in Oslo to agree on a new term and formally categorise ‘non-coeliac gluten sensitivity’ (NCGS) as being distinct from coeliac disease or a specific allergy to wheat,’ explains Norton.
Studies show patients experiencing gastrointestinal symptoms from gluten consumption who do not have coeliac disease.
‘For example, there are numerous studies that show patients experiencing gastrointestinal symptoms from gluten consumption who do not have coeliac disease. One study found patients with gluten-related IBS symptoms, but who had no mucosal (lining) damage – a characteristic of coeliac disease.
‘Other well-recognised research has paved a way forward for greater comprehension, and for NCGS to be taken seriously in its own right – distinct from coeliac disease. Interestingly, further research is looking at not only the health of the gut and gluten, but also gluten’s neurological effect.’
Diagnosing non-coeliac gluten sensitivity
NCGS has historically been harder to diagnose than coeliac disease, as it does not fit the same criteria. ‘Very often, genuine gluten intolerance or sensitivity is misunderstood and can be brushed aside by professionals,’ explains Norton.
‘Patients who are thought to be gluten sensitive by their doctor may have been referred for antibodies tests or indeed, biopsy, but neither of these methods is accurate for non-coeliac gluten sensitivity sufferers,’ she adds.
‘Doctors may test for an immune response to only one type of protein gliadin, called alpha-gliadin, but there is more than one type of these proteins found in gluten. Therefore, a negative result for this antibody does not fully rule out an immune response to other types of gliadin.’
Non-coeliac gluten sensitivity symptoms
Symptoms of NCGS vary, but may include the following:
- Abdominal pain
- Joint pain
- Muscle pain
- Leg or arm numbness
- Chronic fatigue
⚠️ The range of symptoms displayed, and the severity of these, varies considerably between individuals.
How common is non-coeliac gluten sensitivity?
The overall prevalence of NCGS in the general population is unknown, largely due to the fact that many people self-diagnose and start a gluten-free diet of their own accord, without consulting a medical professional. You should always consult a certified medical professional if you suspect something is up.
Some experts believe that the incidence of non-coeliac gluten sensitivity is likely to be higher than coeliac disease and wheat allergy, estimating that it affects 0.63–6 per cent of the population.
Is gluten really always the culprit?
While NCGS is a recognised condition, emerging research indicates that, for some people, it might not actually be gluten causing their digestive symptoms, but malabsorption of a group of fermentable carbohydrates, known as FODMAPs, explains Grosse.
‘FODMAPs include a range of foods, like certain fruits (apples, pears), vegetables (leeks, onions, garlic), dairy products and legumes,’ she says. ‘A study at Monash University in 2013 studied a group of people who reported gluten made them worse, although they did not have coeliac disease. A low-FODMAP diet significantly reduced their symptoms. Participants who had reported improvements in GI symptoms on a gluten-free diet before the study had even fewer symptoms on a low FODMAP diet.’
When the participants were given gluten after following the low-FODMAP diet, there was a surprising result. ‘When gluten was challenged with these participants, up to the equivalent of 10 slices of wheat bread, there was no difference in symptoms,’ reveals Grosse. ‘In other words, gluten had no effect on symptoms.’
This, says Grosse, has led to much debate about whether NCGS is a distinct clinical diagnosis.
Non-coeliac gluten sensitivity treatment
It’s not recommended that individuals embark on a gluten-free diet without professional guidance, as there is a risk of becoming low in fibre and B vitamins if this is not done properly.
‘If you are experiencing gastrointestinal symptoms and your GP or gastroenterologist has ruled out coeliac disease, see a dietitian with an interest in gut health and digestive diseases,’ advises Grosse. ‘They can help you identify if foods are a trigger, and how to manage your symptoms while optimising your food variety.’