Food allergy
and Carola Felchner, science journalistFabian Dupont is a freelance writer in the medical department. The human medicine specialist is already doing scientific work in Belgium, Spain, Rwanda, the USA, Great Britain, South Africa, New Zealand and Switzerland, among others. The focus of his doctoral thesis was tropical neurology, but his special interest is international public health and the comprehensible communication of medical facts.
More about the expertsCarola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.
More about the experts All content is checked by medical journalists.
In the case of a food allergy, the immune system reacts to actually harmless components of the food, such as the proteins in peanuts. In Germany, around four percent of children and two to three percent of adults suffer from it. Read here how a food allergy manifests itself, how it differs from a food intolerance and how it can be diagnosed and treated!
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. T78
Food allergy: description
In the case of allergies, the immune system usually reacts to harmless foreign proteins - for example from pollen (for hay fever) or house dust mites (for house dust allergy) - and forms IgE (immunoglobulin E) antibodies against them. In the case of a food allergy, various dietary proteins are usually incorrectly classified as a threat by the immune system. But that happens comparatively rarely: while around 14.8 percent of people in Germany suffer from hay fever, only around three to four percent have a food allergy.
Certain food (groups) are more likely to cause food allergies than others. These include, among others:
- Nuts (e.g. peanuts)
- wheat
- milk
- seafood
- soy
- Chicken eggs
It has not yet been precisely clarified why the immune system reacts excessively to certain food components in some people. In addition to environmental factors, hereditary components also play a role here.
Food allergy in children
Small children develop a food allergy particularly easily because their intestinal wall does not yet function as reliably as in an adult. This is why they are more likely to come into contact with food components and cells of the immune system. Proper nutrition - depending on the age of the child - is therefore important.
It is best to breastfeed infants. Breast milk provides the child with all the necessary nutrients in the right composition. In addition, breastfeeding generally prevents the development of an allergy - including a food allergy. Such an allergy is therefore rare in infants who are fully breastfed. However, it can develop when certain food components that the mother consumes get into the breast milk and via it to the child.
Infants who are not or only partially breastfed should only be fed infant formula. Foreign milk such as cow's milk should not end up in the bottle in order not to promote the development of allergies.
Atopy
Atopy is the genetic (hereditary) predisposition to develop an excessive defense reaction and one or more diseases of the so-called atopic group of diseases in contact with allergenic substances (allergens). In addition to food allergies, these also include, for example, pollen allergies (hay fever), allergic asthma and neurodermatitis. Some people with atopy (atopics) only develop one such disease, others several - either at the same time or one after the other. A food allergy often occurs in early childhood. Other atopic diseases such as neurodermatitis and / or hay fever often follow later.
While a food allergy is more of a problem for children, hay fever usually only develops in adolescence or adulthood.
Cross allergies
The antibodies (IgE) that the immune system develops against the food component in the event of a food allergy can then also be directed against allergens with a similar structure from other sources. One then speaks of a cross allergy. For example, children with a food allergy to apples are usually hypersensitive to birch pollen.
If a food allergy test shows that someone is allergic to certain foods, the person should also be tested for known cross-allergies. This is possible through a more detailed allergy test. Food and other environmental substances such as pollen, which trigger allergy symptoms in the patient, can be detected in this way and avoided if possible in the future.
Food allergy and intolerance
Many people mix the terms food allergy and food intolerance in everyday life - but these are two different diseases. In contrast to allergies, intolerance does not result in a reaction of the immune system, nor are IgE antibodies detectable in the blood.
Instead, physical processes are disturbed in the case of food intolerance, so that the body either cannot properly absorb the food in question or a certain component of it (e.g. milk sugar = lactose) or cannot process it properly. As a result, symptoms such as abdominal pain and flatulence occur.
Well-known food intolerances are lactose intolerance and histamine intolerance.
Exactly what type of disease celiac disease (gluten intolerance) is, has not yet been conclusively clarified. In any case, it has elements of both an allergy and an autoimmune disease.
Food allergy: symptoms
Food allergy symptoms can vary - both in type and in severity. Often there are reactions on the mucous membranes, for example in the form of:
- Inflammation of the lining of the intestine
- watery and puffy eyes
- runny nose and urge to sneeze
- Coughing or asthma attacks with shortness of breath
But skin rashes, eczema, reddened skin, the formation of wheals and itching, as well as diarrhea, nausea or flatulence often occur with a food allergy.
Mild food allergy symptoms are difficult to identify and can often only be clearly identified with a food allergy test.
The most severe form of the allergic reaction is anaphylactic shock. Because the cardiovascular system can fail, there is an acute danger to life! Call the ambulance immediately!
Food allergy severity
There are defined degrees of severity of an allergic reaction, according to which the medical treatment is also oriented:
Grade 0: In the slightest allergic reaction, only redness, swelling or itching occurs on the mucous membranes that have come into contact with the food. There is no body-wide reaction.
Grade 1: The whole body reacts to the first degree of food allergy: skin rashes, redness, wheals and itching are often the first signs. Headaches, hoarseness and restlessness can also occur. There is no danger to life, but the patient should be observed closely. In this way, it can be recognized at an early stage if his condition is worsening.
Grade 2: In addition to the symptoms of the first degree, there are shortness of breath, dizziness, and the urge to urinate and defecate. The pulse is fast and the blood pressure is low.
Grade 3: The symptoms of the first two grades are accompanied by a threatening shortness of breath. There is involuntary leakage of stool and urine. Those affected often vomit. Their consciousness is clouded and they can only be addressed to a limited extent.
Grade 4: The patient loses consciousness, suffers respiratory and circulatory arrest, the blood supply to vital organs collapses. Such an anaphylactic shock is life-threatening and must therefore be treated by an emergency doctor as soon as possible in order to be able to save the patient.
Food allergy: causes and risk factors
How and why some people develop a food allergy is not yet fully understood. However, it can be assumed that the predisposition to this is hereditary. Depending on which environmental stimuli are added, an allergy may or may not develop.
When coming into contact with a certain substance from food, the immune system is sensitized to it in unfavorable constellations. As a rule, these allergenic substances (allergens) are proteins. The immune system makes certain antibodies against the allergen in question, namely immunoglobulins of the IgE type. If the person comes into contact with the allergen again, the IgE activate other immune cells, the so-called mast cells. They release the messenger substance histamine, which causes the mucous membranes to swell, causes itching and triggers a multitude of inflammatory reactions in the body.
Protective breast milk
Breastfeeding offers good protection against food allergies.In particular, infants whose parents suffer from allergic diseases themselves should be fully breastfed in the first six months of life. If mna starts feeding beforehand, the risk that the baby will develop a food allergy increases.
Hygiene promotes allergies
In the past few decades, allergies have clearly gained ground in industrialized nations. The reason for this could be the pleasantly good hygienic conditions. Although they protect against other diseases, they may have the consequence that the immune system does not have enough training opportunities in adolescence. It then learns less well to differentiate between harmless and dangerous foreign substances. It then also tolerates harmless foreign substances less well, which could promote the development of allergies.
In fact, children who grow up in the country (especially on farms) are less likely to have allergies. People with parasites (e.g. worms in the intestines) are also less likely to get sick. Experts call this possible connection between hygiene and allergies the hygiene hypothesis.
Food allergy: examinations and diagnosis
Finding out whether and, if so, what food allergy someone suffers from is not always easy. The doctor gains the first important information from the conversation with the patient (anamnesis), in which he has the complaints and possible temporal connections with the food intake described. Another important note is if the patient also suffers from hay fever or other allergic diseases, for example - an additional food allergy is more likely.
With a food allergy test of the skin (prick test), the doctor can test the reaction of the immune system to certain allergens, such as apple components. To do this, he introduces components of various possible allergens into the patient's skin through a small crack. This food allergy test is positive if the body reacts to an allergen with reddening of the skin. Depending on the severity and diameter of the reddening, the doctor can assess the severity of the allergy.
In rare cases, a so-called provocation test is necessary. The patient takes a small amount of the possibly allergy-causing food under medical supervision. The doctor closely watches whether an allergic reaction develops as a result. In the case of a severe allergy, this reaction can be very violent, up to and including anaphylactic shock. Therefore, caution and careful medical observation are very important during a provocation test - if necessary, the doctor must quickly administer medication to the patient against the life-threatening shock.
Food allergy: treatment
A food allergy cannot yet be treated causally. As a rule, the only thing left for those affected is to consistently avoid the triggering allergen - and thus all foods that contain it. Comprehensive information and diet advice is therefore a basic requirement for successfully dealing with a food allergy.
It is problematic for allergy sufferers that most manufacturers do not provide a complete list of ingredients for their products. The most common allergy-causing foods (such as nuts, eggs, milk or soy) now have to be declared on packaging, even if they are only contained in traces.
People with a severe food allergy must always have an emergency kit with them that contains medication in the event of a severe allergic reaction after accidentally ingesting the allergen: a fast-acting antihistamine, a glucocorticoid, and an adrenaline (or epinephrine) supplement. These drugs can save the life of those affected in an emergency.
Food allergy: course and prognosis
A food allergy that already occurs in infancy often disappears before starting school. A food allergy that emerges later, on the other hand, usually accompanies those affected for a lifetime.
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