The gluten-free diet has become a trend – many people choose gluten-free products even though these have no benefit for their health. In only about 1% of the population does gluten trigger inflammatory reactions in the gut. People with coeliac disease meet with more understanding today, and there are better diagnostic methods than 20 years ago. But what exactly is coeliac disease, how does it manifest itself and who is particularly susceptible to it?
What is coeliac disease?
Coeliac disease is a chronic food intolerance to gluten which, if untreated, leads to chronic damage to the small intestinal mucosa. Gluten is also known as gluten protein and is known for its good baking properties in combination with water. It occurs in the grains of cereals (such as wheat, rye, spelt and barley) and can trigger an overreaction of the immune system in some people. In people with coeliac disease, the body forms antibodies against its own cells of the small intestine. Coeliac disease is therefore also counted among the autoimmune diseases. The immune reaction can lead to regression of the villi of the small intestine; the mucosa flattens, and food components can no longer be fully absorbed by the damaged areas. The disease lasts a lifetime and cannot be cured. However, on a strictly gluten-free diet, the damage to the small intestine can regress.
How does coeliac disease manifest itself?
When people with coeliac disease eat gluten, inflammatory reactions occur in the small intestine. The symptoms are varied but not equally pronounced in all those affected. Nor do the typical symptoms have to occur, and they need not manifest themselves only in the gastrointestinal tract. Headaches and aching limbs, tiredness and fatigue, depression and migraine attacks can also point to coeliac disease. These diffuse and ambiguous symptoms make the disease difficult to recognise. As a result, it often takes years until a diagnosis of coeliac disease is made. Courses with few or no symptoms predominate. Because of the clinical picture of so-called subclinical coeliac disease, researchers and doctors assume that the number of undiagnosed cases is very high. Typical signs include:
Anaemia, pallor
Swollen face, fluid retention
Diarrhoea with fatty stools
Flatulence, hard distended abdomen, abdominal pain
Weight loss, sometimes also increased appetite
Deficiency of certain nutrients, especially iron and folic acid
How is coeliac disease diagnosed?
Doctors have various criteria for diagnosing coeliac disease. The combination of these criteria that can be demonstrated in a patient may vary.
Biopsy of the small intestine before the change in diet: the most important diagnostic method in adults. The Marsh classification is used to divide the destruction of the small intestinal mucosa into various categories.
Genetic test: about 90% of those affected have the gene HLA-DQ2, the others HLA-DQ8. The genetic test alone is not sufficient for diagnosis. In cases with severe symptoms, the genetic test is used in addition
Blood test for antibodies before starting the diet: raised transglutaminase antibodies in the blood.
The patient’s symptoms are also taken into account, especially if the typical signs mentioned above occur
Resolution of symptoms on a gluten-free diet
If coeliac disease is suspected, it is important to see a doctor. The doctor usually first orders a blood test and a genetic test. The blood is then examined for certain antibodies that play a role in coeliac disease. These are antibodies directed against the enzyme transglutaminase (anti-TG) and against the endomysium (EmA). They circulate in the blood, attack the enzymes and trigger the inflammatory reaction of the intestinal mucosa. However, false-negative results can occur if the patient has IgA deficiency. This is frequently associated with coeliac disease. All class A antibodies (total IgA) should therefore also be measured.
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About 30–35% of the total population are HLA-DQ2 or DQ8 positive. The HLA gene is located on chromosome 6. But only 2% develop coeliac disease in the course of their lives. For this reason, research into the causes continues. Genes alone are not responsible for the development of coeliac disease. The genetic test is particularly useful for ruling out coeliac disease (no HLA-DQ2 or DQ8 gene detectable).
Small intestinal biopsy is used to diagnose coeliac disease beyond doubt. However, a positive genetic test, typical symptoms and resolution of symptoms on a gluten-free diet are also evidence of coeliac disease. In children and adolescents, a biopsy is not always necessary if certain thresholds are exceeded in the blood test (transglutaminase antibodies more than 10 times the normal range).
Frequency of coeliac disease in the population
Coeliac disease is triggered by the consumption of gluten in genetically predisposed individuals (with the HLA-DQ8 and DQ2 gene). Today, the prevalence of coeliac disease in Europe, particularly in Germany, averages 1% (1:100). Women are affected about twice as often as men. As recently as 20 years ago, the frequency was 1:1,000 to 1:2,000. However, these data are based on manifest coeliac disease with typical symptoms. With the development of new screening and diagnostic methods, especially the detection of antibodies in the blood, it has been shown that coeliac disease occurs more frequently. Today, researchers know about the varied symptoms of people with coeliac disease and that most show a subclinical course. The prevalence could therefore be much higher than assumed. Coeliac disease is now increasingly diagnosed in adulthood, between the ages of 20 and 50. Children are most frequently diagnosed with coeliac disease between the ages of 1 and 8.
Why are there more people with coeliac disease than before? In addition to better diagnostic methods, researchers assume that gluten itself is to blame for this development. In particular, wheat starch obtained from wheat is widely used by industry as a filler and binding agent. A large number of (convenience) foods and products today contain wheat starch.
Conditions associated with coeliac disease
Patients with coeliac disease have an increased risk of other immunological diseases. These are often diagnosed first. It is therefore important, if such a disease is present, also to be tested for coeliac disease, especially if symptoms occur after eating foods containing gluten.
Type 1 diabetes mellitus: 5–8% of diabetics have coeliac disease
Skin manifestation: dermatitis herpetiformis Duhring, also called coeliac disease of the skin: 100%
Thyroid diseases: above all Hashimoto’s thyroiditis (8%) and Graves’ disease
Autoimmune hepatitis
Rheumatoid arthritis
Crohn’s disease and ulcerative colitis
…and others
People with Down syndrome and Turner syndrome also have a relatively high risk of developing coeliac disease during their lives.
Treatment of coeliac disease
Even 1/4 g of wheat leads to inflammation of the small intestinal mucosa. Better health can only be achieved by strictly avoiding gluten. The only treatment currently available is a lifelong, strict gluten-free diet.
The disease is stopped solely by consistently and permanently omitting the damaging cereal protein. The small intestinal mucosa regenerates by itself; the intestinal villi grow back and resume their function.
Research is being carried out on a number of active substances, all of which are still being tested in clinical trials at various stages. Current research topics, all the important gluten-free foods and tips on how people with coeliac disease can best cope with the change in diet are summarised in the article on diet and coeliac disease.
People with coeliac disease must also watch out for gluten-containing ingredients, especially wheat starch and other wheat derivatives, in medicines, lipsticks and toothpaste – i.e. anything that comes into contact with the mouth and could therefore be swallowed accidentally. For medicines (except nasal drops), the German Coeliac Society assumes that the amounts taken in are so small that patients with coeliac disease need not worry.
Depending on how severely the small intestine is damaged, existing deficiencies must be corrected. Vitamins and minerals such as vitamin B12, folic acid and vitamin D can be supplemented. Dosage recommendations are given by the treating doctor.
