Letzte Aktualisierung am 5. May 2025 von Dr. Michael Zechmann-Khreis
In contrast to food intolerances , food allergies are immunologically mediated hypersensitivity reactions to certain food components, especially proteins. They can occur even when very small quantities (traces) are consumed and affect people of all ages. However, children are more frequently affected than adults. The most common triggers are peanuts and cow’s milk (in children) and wheat, shellfish, soy and celery (in adults).
What is a food allergy?
In the case of a food allergy, the immune system reacts hypersensitively to certain proteins in food. Food allergies are IgE-mediated immediate type allergies (type I), where symptoms usually appear within minutes of consumption. In the case of intolerances such as histamine intolerance , symptoms occur up to 4 hours after consumption. These reactions can range from mild symptoms to life-threatening conditions, although this is rare. You can have a direct allergic reaction to the protein in the food (primary food allergy) or a cross-reaction with a food due to a pollen allergy, for example (secondary NMA).
How common are food allergies?
The frequency of food allergies has increased in some countries in recent years. Peanut and tree nut allergies in particular are on the rise. Children are affected more often than adults. The data is not consistent here. Children are likely to be affected between 4.5 and 7 %, adults between 3 and 5 %. Children mainly have primary allergies to basic foods, adults have secondary allergies. Adults are very unlikely to develop a primary allergy to staple foods. The exception is fish allergy, which can occur at any age. The most common triggers of food allergies in adults include apple, peanut, kiwi, hazelnut, peach, cow’s milk, hen’s egg, wheat, fish and shrimp. Even more common than genuine primary food allergies, however, are cross-reactions caused by sensitization to inhaled allergens. In German-speaking countries, birch pollen-associated food allergies are particularly widespread. This form of allergy usually develops in adolescence or adulthood and can persist in the long term.
We also know that the frequency of NMA is determined by gender. Women are affected more often than men. Family history and other allergies are also decisive for the risk.
Symptoms
The symptoms of a food allergy can be varied and affect different organ systems:
- Skin: itching, redness, wheals
- Mouth and throat: swelling, itching, tingling
- Gastrointestinal tract: nausea, vomiting, diarrhea, abdominal pain
- Respiratory tract: cough, shortness of breath, asthma
- Cardiovascular system: In (very rare) extreme cases, anaphylactic shock may occur
Diagnosis
The diagnosis of a food allergy is made by:
- Nutrition and symptom diary
- Medical history – detailed survey of the patient’s medical history
- IgE blood test and/or skin test (prick test) – these tests alone are not sufficient for diagnosis!
- Blood tests (specific IgE antibodies)
can still be carried out optionally: - Elimination diet
- Provocation tests under medical supervision
The differential diagnosis of e.g. lactose intolerance or fructose intolerance, mastocytosis or other diseases is important. IgG/IgG4 determinations are not valid methods for NMA. Neither are bioresonance, electroacupuncture or kinesiology.
Treatment
In most cases, primary food allergies in children heal themselves spontaneously at school age. This sounds esoteric, but it simply means that the immune system has learned and no longer reacts excessively. In medicine, this is called spontaneous remission. The natural course of a food allergy is highly dependent on the triggering food: Allergies to cow’s milk, hen’s egg, wheat and soy often resolve spontaneously in the first few years of life. In contrast, allergies to peanuts, tree nuts, fish and crustaceans tend to persist. Nevertheless, tolerance can also develop with these allergies.
The primary treatment consists of treating acute reactions and long-term strategies to consistently avoid the triggering allergen. Patients should be informed about cross-reactions and hidden allergens. If there is a high risk of severe reactions, an emergency kit is recommended, consisting of
- Adrenaline autoinjector
- Antihistamine
Oral immunotherapy can be considered in specialized centers for certain allergies (e.g. peanut).
Prevention
It is recommended to prevent food allergies:
- Breastfeeding in the first 6 months of life, even if bottle feeding is also used
- Introduction of potential allergens between the 5th and 7th month of life; hen’s egg only in cooked or baked form; nuts in age-appropriate form (e.g. nut butter)
- No preventive diets during pregnancy or breastfeeding without a doctor’s recommendation.
- Pro- or prebiotics are not suitable for preventing allergies.
Food allergies require a precise diagnosis and individualized management. By educating themselves, avoiding the triggers and taking medical measures, those affected can lead a largely normal life. A specialist should always be consulted in case of suspicion.
Sources
- Worm al. (2021, extended 2025). S2k guideline: Update guideline for the management of IgE-mediated food allergies S2k guideline of the DGAKI. Allergology, Volume 44, No. 7/2021, pp. 488-541
- Federal Center for Nutrition (BZfE): www.bzfe.de
- German Society for Allergology and Clinical Immunology (DGAKI): www.dgaki.de
