Did you know that the body can react to proteins to which it is not allergic?

An allergy is when the body becomes hypersensitive to substances that are normally harmless, such as pollen proteins. When the immune system is activated, it tries to destroy the perceived pathogen, resulting in the familiar allergic symptoms.

A cross-allergic reaction occurs when the immune system recognises a protein from a substance to which the person is not actually allergic (e.g. fruit or vegetables) and associates it with the protein to which the person is actually allergic (e.g. pollen). As these two proteins are related but not identical, the immune system may react in a similar way and in some cases cause allergic symptoms. This phenomenon is known as pollen-food allergy syndrome (PFAS) or oral allergy syndrome (OAS).

It is interesting to note that around 70 per cent of birch pollen allergy sufferers are affected by PFAS. PFAS are often associated with specific allergens. For example, birch pollen can cross-react with apple, almond, carrot, celery, cherry, hazelnut, kiwi, peach, pear and plum. Grass pollen can cross-react with celery, melon, orange, peach and tomato, and ragweed pollen with banana, cucumber, melon, sunflower seeds and zucchini.

If you suffer from PFAS but don't want to give up the fruits and vegetables that cause these annoying symptoms, there is a simple solution: heating fruits and vegetables changes the proteins so that the immune system no longer recognises them as enemies. This means you can still enjoy the healthy nutrients and vitamins from fruit and vegetables without having to worry about allergic reactions.

_Sources:

_{Allergiezentrum Schweiz, Kreuzreaktionen, https://www.aha.ch/allergiezentrum-schweiz/allergien-intoleranzen/nahrungsmittelallergien/kreuzreaktion (aufgerufen am 12.03.2024)}

_{American College of Allergy, Asthma and Immunology, Pollen Food Allergy Syndrome (21.03.2019), https://acaai.org/allergies/allergic-conditions/food/pollen-food-allergy-syndrome/ (aufgerufen am 12.03.2024}