Causes

If a food allergy exists, an immunological reaction occurs in contrast to a food intolerance. This means that the body’s own immune system, which normally protects us from bacteria and viruses, is the trigger of the food allergy. The food allergy is based on an antibody-antigen reaction.

The body’s own antibodies usually ensure that foreign substances and microorganisms are recognized and combated. In the context of a food allergy, the antibodies bind to certain proteins of the food (antigens). This causes an immune reaction of the body, which can manifest itself with the symptoms described in more detail below.

It is unknown what causes the allergy to develop. Since some people do not develop allergies, but other people often do, it can be assumed that genetic factors also play an important role in the development of an allergy. Due to the observation that the number of allergy sufferers in the population has been steadily increasing for several decades, a number of hypotheses have been formulated.

One of the most important theories is the hygiene hypothesis. In this hypothesis it is assumed that excessive hygiene does not stimulate our immune system sufficiently at a young age.This underchallenge of the immune system is said to favour the occurrence of an allergy. Further hypotheses concern among other things the changed habits of humans (with increased stress and a changed nutrition) and an increasing environmental pollution by humans.

Until today, however, no hypothesis can provide an even remotely satisfactory explanation for the phenomenon of allergy. In principle, a food allergy can develop for all foods. Foods that are almost never allergenic are rice, artichokes and leaf salads.

Nevertheless, certain foods or components of these foods are overly common allergens. These include the protein gluten, dairy products (especially the lactose contained in cereal products), peanuts, chicken protein, nuts, fish, crustaceans and molluscs, and soybeans. It is noticeable that, depending on the age of the person affected, various allergens can be identified as triggers for food allergies.

Infants and toddlers in particular suffer from allergies to basic foods such as cow’s milk, soy and wheat. Adolescents and adults, on the other hand, are much more frequently affected by allergies to fruit, vegetables, nuts and spices. If there is already an immunological hypersensitivity to certain food components, a special form of allergic reaction can be the cause: the cross-allergy.

This is a reaction to substances that are structurally similar to another allergen. Thus, people who are allergic to different pollen and grasses can develop hypersensitivity to certain fruits. Typical cross-allergies also exist between latex and fruits like banana, kiwi and avocado. Sometimes people are not allergic to the food itself, but to certain ingredients, e.g. the histamine in fresh tomatoes.