Food allergy - symptoms, triggers and treatment

Food allergy - symptoms, triggers and treatment

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Food allergy

Allergy to certain proteins in food can affect children and adults. The immune system is hypersensitive to normally harmless proteins that are found in many natural and healthy foods. Symptoms mainly affect the skin, the gastrointestinal tract and the respiratory tract. Detecting the triggering allergen is not always easy, but it is a necessary basis for therapy. This consists primarily of (temporarily) avoiding appropriate foods. Newer treatment approaches, such as immunotherapy, and also prevention options are part of current research.


Allergy is an excessive reaction of the immune system to certain allergens. So there is also a non-toxic, allergic hypersensitivity (hypersensitivity) in food allergy, which arises as a reaction of the immune system to certain foods or their components (proteins). The vast majority of food allergies are classified as type I allergies of the immediate type.

It is important to differentiate other non-allergic hypersensitivity reactions with similar symptoms that are not caused by an immune response. This means that intolerances or intolerances to certain foods and additives are not "real" food allergies. Some of these reactions belong to the so-called pseudo-allergies.

A basic distinction is made between primary and secondary food allergy. Children are predominantly affected in the primary forms and the reactions caused by absorption in the gastrointestinal tract can be very difficult.

Secondary forms are often accompanying symptoms of pollen allergies (pollen-associated food allergies). Those affected, for example who have an inhalation allergy such as hay fever, react to plant foods whose protein structures resemble those of the primary allergen (e.g. the Bet-v-1 protein from birch pollen and the Mal-d-1 protein in the apple). In this context, one also speaks of a cross allergy.

The general incidence of allergic diseases (atopies) has increased significantly in recent decades, particularly under the influence of western lifestyle, so that allergies have become a major public health issue. According to the Robert Koch Institute, almost twenty percent of adults in Germany suffer from at least one allergic disease. The “real” food allergies are actually less common than generally assumed. Less than five percent of the adult population are affected. In contrast, there is a different prevalence in Germany among children and adolescents. Around twenty percent are sensitized to at least one food allergen. Over the lifetime, slightly more women suffer from the allergic reactions than men.


The reactions and complaints of a food allergy are very diverse and vary in severity (grades one to four), whereby very small amounts of a certain food or the corresponding protein molecules are sufficient to cause violent immune reactions. The dose is therefore not critical. The symptoms usually appear immediately, i.e. only a few minutes to hours after contact. After a while (up to 2 days later), the symptoms can appear repeatedly.

Typical signs often appear on the skin and on the mucous membranes after direct contact with the allergen. These include, for example, swelling on the face (angioedema) as well as on the hands or legs, reddening of the skin, wheals and an itchy rash (also urticaria). In the secondary forms, there is often a feeling of itching or burning and swelling in the mouth and throat.

At the same time, the respiratory tract may be affected or conjunctivitis may occur. Gastrointestinal complaints such as nausea and vomiting, diarrhea, constipation and / or flatulence can arise from the digestive tract. But complaints of the cardiovascular system can also be added.

The most severe form of an allergic reaction is also known as anaphylactic shock. This represents a medical emergency, since the symptoms that occur represent an acute danger to life. In addition to the skin reactions, this can lead to a sudden drop in blood pressure and loss of consciousness. Swelling in the airways can become so severe that it causes shortness of breath. The worst outcome is circulatory shock and respiratory arrest.

Whether, as sometimes suspected, food allergies are also triggers for the appearance of neurodermatitis (atopic dermatitis) must be checked in each individual case and is not considered to be fundamentally proven.


In contrast to the incompatibilities, in which there is, for example, a lack of enzymes or malfunctions in the digestive organs, an allergy is a reaction of the immune system, in which harmless proteins in excess are combated with antibodies (mostly IgE antibodies) .


The most common foods that contain the triggering proteins are different in the primary form than in the secondary form. For children with a primary food allergy, the following basic foods (often after processing) are the main triggers:

  • Cow's milk,
  • Chicken egg,
  • Legumes (soy),
  • Wheat,
  • Nuts (peanut, walnut, hazelnut),
  • Fish.

In adults, on the other hand, there are usually secondary allergies, which in addition to the foods mentioned are not based on cow's milk and chicken eggs, but rather on vegetables (celery, carrots), pome fruit and stone fruit, as well as seafood. In most cases, those affected react to more than one allergen.

In general, fruits and vegetables seem to produce less strong reactions than nuts or shellfish.

Paths of origin

How the allergic reactions occur has not yet been fully clarified. It is believed that there is some benefit from genetic predisposition and certain environmental factors. Furthermore, factors such as physical exertion, alcohol or acetylsalicylic acid seem to favor, trigger or even aggravate the occurrence of the symptomatic reaction.

For most of the cases examined, the involvement of IgE antibodies (immunoglobulin-E) in the immune response could be demonstrated. Immune cells (for example lymphocytes) also play a role in the defense primarily in gastrointestinal problems. There are also processes in which both occur.


To detect or rule out an existing allergy, examinations over a longer period are usually necessary. Only with extensive diagnostics can it be ensured that it is actually an allergy and not an intolerance reaction, the symptoms of which are sometimes very similar. Reactions of the body to glutamate or histamine-containing foods can, for example, cause a comparable clinical picture as well as a fructose and lactose intolerance. In addition, inflammatory bowel diseases are included in the differential diagnosis.

Part of a detailed patient survey is often a nutritional and symptom diary of several weeks (with the time), in which those affected should record as precise information as possible about their meals, drinks and symptoms.

Test procedure

If there is a suspicion of an allergy, mostly skin tests, which show a skin reaction to induced proteins, and blood tests to determine IgE are also initiated.

A well-known standard skin test is the so-called prick test, in which various allergens are superficially introduced into the skin of the forearm (mostly commercial test solutions). If there is redness, itching or wheals, this indicates an allergic reaction. However, these methods are often not clear or sufficient to ultimately make a reliable diagnosis or to determine the trigger. The test results can only indicate sensitization, but not whether symptoms and an allergy are actually triggered.

If there is still no clear evidence by skin and blood test, but there is already a concrete suspicion, an omission diet with the potentially allergy-causing food may help. Those affected do not use this food for up to two weeks, which can lead to an improvement in symptoms. If, after this phase and when the appropriate food, the so-called provocation test, resumes, the allergy is confirmed. This test is usually carried out under medical supervision, as it can sometimes lead to a dangerous immediate reaction.


Conventional therapy for primary and secondary allergies, in addition to short-term acute measures against symptoms, mainly consists of a long-term strategy to prevent further allergic reactions.

Change of diet

After a confirmed diagnosis by means of appropriate allergy tests, the most important and lasting therapy is to avoid the allergens found and to change the diet accordingly. Nutritional counseling and education about food allergens offer good support here.

It should be checked at regular intervals whether a so-called elimination diet is still necessary. It is possible that the allergy will go away under the waiver, especially in children.

If no specific food was found to be allergy-causing during the diagnosis, there is also the possibility of a generally low-allergen diet (oligo-allergenic diet) with selected foods. This can lead to symptom relief and is sometimes already used for diagnostic purposes.


The administration of medication (antihistamines or cortisone) for acute symptomatic treatment is only used for a short time and usually only for more serious symptoms.

The emergency situation in the event of sudden anaphylactic shock must be distinguished from this. Emergency medical treatment and the quick administration of medication are vital here. Adrenaline is used primarily, later also antihistamines and glucocorticoids. If there is an increased risk of such severe immediate reactions, those affected should be informed and prepared accordingly.

Possibilities of immunotherapy still in the test phase

Various studies and test series for the treatment of primary food allergies by special immunotherapies (hyposensitization) have so far not shown uniform results and there is still insufficient data on the long-term effects. Oral or subcutaneous immunotherapy has so far only been used under medical supervision and in clinical studies and is not yet considered a general treatment recommendation.

The use of immunotherapies is also being researched in the secondary forms. According to the currently available guidelines, therapies with pollen allergens should only take place if there are symptoms of the respiratory tract due to a pollen allergy.

Further research approaches focus on prevention options. So far, however, there have been no results for concrete recommendations.

Naturopathic treatment and alternative therapy options

The triggering allergen should also be identified and avoided as possible from a naturopathic perspective. In addition, naturopathy offers an abundance of methods to change the body and to positively influence or normalize the immune reactions of the body.

Combined with a change in diet, the following types of therapy offer further opportunities for improvement:

  • Autologous blood therapy,
  • Own urine therapy,
  • Symbiosis steering,
  • Immunomodulation with naturopathic medication,
  • Dark field diagnostics and milieu therapy,
  • Acupuncture,
  • Homeopathy,
  • Hypnotherapy,
  • Therapeutic fasting.

According to individual indications and under expert guidance, the listed naturopathic treatments and alternative treatments can additionally help those affected. (jvs, cs)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Dr. rer. nat. Corinna Schultheis


  • Helmholtz Zentrum München (ed.): Allergy Information Service - Food Allergy Disease (accessed: June 25, 2019), allergieinformationsdienst.de
  • Fischer, Peter: Parent advisor to the Society for Pediatric Allergology and Environmental Medicine - Food Allergies, in: Pediatric Allergology in Clinic and Practice, Issue 03/2015, gpau.de
  • Robert Koch Institute: Allergies and Atopic Diseases (accessed: June 25, 2019), rki.de
  • Bergmann, Karl-Christian, Heinrich, Joachim, Niemann, Hildegard: Current status of the spread of allergies in Germany. Position paper of the Commission for Environmental Medicine at the Robert Koch Institute, in: Allergo Journal International, edition 25/6 (2016), rki.de
  • Worm Margitta et al .: Guideline for the management of IgE-mediated food allergies, in: Allergo Journal International, edition 24/2015, pp. 256-93 (AWMF Sk2 guideline No. 061-031, as of March 2015), awmf.org
  • Worm, Margitta et al .: Food allergy due to immunological cross-reactivities with inhalation allergens, in: Allergo Journal International, edition 23/2014; S.1-16 (AWMF S1 guideline No. 061-019, status August 2013), dgaki.de
  • Werfel, Thomas et al .: Guideline for neurodermatitis [atopic eczema; atopic dermatitis], AWMF S2k Guideline No. 013-027, as of March / 2015, awmf.org

ICD codes for this disease: K52.2, L27.2, T78.0, T78.1 ICD codes are internationally valid encodings for medical diagnoses. You can find e.g. in doctor's letters or on disability certificates.

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