A wheat allergy occurs rarely in adults, but it can take a life-threatening course. Wheat is the food that most commonly triggers a severe and immediate allergic reaction (anaphylaxis) in people over the age of 18. This has been revealed by data from studies in Germany, Austria and Switzerland.
Like milk and egg allergies, wheat allergy generally appears in infancy. Around 0.3 per cent of all children under the age of 5 in Europe are allergic to wheat, as demonstrated through provocation tests. A total of around 0.1 per cent of all Europeans suffer from this allergy.
Wheat contains several different proteins that have a potentially allergenic effect. Some belong to the group of wheat albumins and globulins, while others are part of the gluten fraction.
According to current knowledge, the reaction in primary wheat allergy is triggered when the allergen comes into contact with the intestinal mucosa. Children suffer most frequently from this type of reaction.
An allergy can also be triggered by breathing in wheat flour dust. This is referred to as baker’s asthma, one of the most common occupational respiratory diseases, and affects mainly bakery workers. People with this allergy suffer from allergic rhinitis and/or asthma symptoms but can usually tolerate the wheat in food. The condition can also be triggered by dust from other baking ingredients, such as rye or soya.
A wheat allergy can cause mild or severe reactions in various organs. If the gastrointestinal tract is affected, abdominal pain, vomiting or diarrhoea may occur. The mucosa in the mouth and throat can start to tingle or swell a few minutes to hours after exposure. The skin may also develop allergic reactions. Apart from itching or hives, a wheat allergy can also trigger or worsen an eczema flare-up. In still other cases, the airways can be affected, with reactions ranging from allergic rhinitis to asthma symptoms. Severe reactions may also occur, including anaphylactic shock accompanied by difficulty breathing and circulatory collapse.
Wheat Allergy in Childhood
Allergic reactions often appear a few minutes to hours after a (baby) food containing wheat is consumed for the first time. However, delayed symptoms can also occur; for example, eczema can worsen one to two days after eating wheat. The overall prognosis for wheat allergy is positive. Like cow’s milk and egg allergies, it usually subsides by adolescence. The allergist can perform a test 12 to 18 months following diagnosis to check whether the allergy is still present so that children may resume wheat consumption as soon as possible.
Wheat Allergy in Adulthood
Although rare, WDEIA (wheat-dependent exercise-induced anaphylaxis) is a special form of wheat allergy that can progress to a very severe stage.
The strange thing about WDEIA is that adults and adolescents with this allergy can normally tolerate wheat. They only experience allergic reactions when they engage in physical activity after eating foods containing wheat. In addition to exercise, other triggers have been identified such as alcohol, (pain) medication, stress, or hormonal factors such as menstruation in the case of women. If one of these exacerbating factors coincides with wheat consumption, allergic reactions occur 30 minutes to six hours later. These can include itchy skin, wheals, hives or facial swelling. There may also be abdominal pain, diarrhoea or vomiting. In some cases, difficulty breathing, low blood pressure, heart palpitations and even circulatory collapse may occur.
As a first step in diagnosing a wheat allergy, the doctor asks the patient about his or her symptoms and eating habits. Some patients are advised to keep a food diary in which they take note of what they eat and any symptoms that occur. If an allergy is suspected, skin and/or blood tests are conducted in order to confirm it. These tests reveal an allergic disposition to certain substances but do not provide evidence of an actual allergy. For this reason, an additional diagnostic procedure, the provocation test, is conducted to rule out any doubts. For this test, the patient eliminates the allergen from the diet for a certain period. He or she is then given small amounts of wheat protein under medical supervision. The results confirm whether wheat triggers an allergic reaction or whether it can be removed from the list of suspected allergens.
If WDEIA is suspected, the blood is tested for the presence of antibodies to omega-5 gliadin, the main allergen involved in this type of wheat allergy. If a provocation test is performed, the patient is given the wheat protein and the suspected trigger is simulated in addition – for example, by having the patient exercise on a stationary bike.
If wheat causes gastrointestinal problems, the patient must be tested for both an allergy and coeliac disease, a serious disorder in which the body produces antibodies to gluten (which is found not only in wheat but also in other types of grains). This results in chronic inflammation in the small intestine and damage to the intestinal villi. In addition to bloating and abdominal pain, diarrhoea occurs frequently. There may also be symptoms of mineral and vitamin deficiencies (such as iron deficiency and osteoporosis). The joints, liver, skin and nervous system can also be affected. Coeliac disease is diagnosed through tests for specific antibodies, genetic analysis, and the analysis of a tissue sample from the small intestine. A diagnosis can only be made if the patient’s diet includes gluten. If bread and pasta have been excluded for some time, the disease cannot be confirmed. If coeliac disease is diagnosed, the patient must strictly avoid gluten, since even small amounts of gluten can damage the intestinal mucosa.
Other gastrointestinal symptoms that mimic a wheat allergy may be caused by non-coeliac gluten sensitivity. The set of symptoms this refers to has not yet been clearly defined. Nor is it clear whether the reaction is triggered by gluten or other components in wheat. Symptoms of gluten sensitivity include abdominal pain, bloating, and in some cases diarrhoea. Patients also report fatigue, headaches, and muscle and joint pain. Gluten sensitivity is confirmed by a diagnosis of exclusion: If the examination results fail to confirm an allergy or coeliac disease and the symptoms subside while on a gluten-free diet, the patient is assumed to have gluten sensitivity. Whether non-coeliac gluten sensitivity actually exists is still widely debated in the medical community.
There is currently no effective treatment for wheat allergies. For this reason, patients must try to avoid wheat. Not only do they have to exclude products containing wheat flour, wheat starch and breading; they may also be intolerant to cereals that are similar to wheat (spelt, freekeh, kamut or emmer). It should also be noted that gluten-free foods are not always safe for people who are allergic to wheat, as they could theoretically contain other allergenic wheat proteins.
In the case of a WDEIA diagnosis, the patient does not necessarily have to avoid wheat all the time. If the triggering factors are known, it often suffices to avoid the triggers for up to six hours after eating wheat. Whether a wheat-free diet is necessary should be determined according to the patient’s individual history. However, patients at risk of an anaphylactic reaction must carry an emergency kit with them containing an adrenaline auto-injector, a corticosteroid and an antihistamine. This also applies to people with a severe (true) wheat allergy who may experience an anaphylactic reaction from exposure to even the smallest trace of wheat protein.
Legal notes: Prof. Dr. med. Dr. h. c. Torsten Zuberbier
Last changes made: July 2016