Food allergy - cross allergy and intolerances: these are the differences

For many, the enjoyment of food is clouded by the discomfort of a food allergy. Symptoms range from itching or nausea to life-threatening conditions. In addition, adult people often also react allergically to food due to an existing pollen allergy. Our medical team reports on the causes of this so-called cross-allergy and informs you all around the topic of food allergy.

Müsli mit Früchten und Joghurt Quelle: Kiian Oksana - Copyright: Scientific DX GmbH, 2018

Was ist eine Nahrungsmittelallergie?

Bei einer Nahrungsmittelallergie richtet sich das Immunsystem gegen - an sich ungefährliche - Eiweiße aus Nahrungsmitteln. Der Körper betrachtet die Stoffe aus der Nahrung als schädlich und reagiert auf diese mit der Produktion von IgE-Antikörpern. Nach dem Kontakt der Lebensmittelallergene mit den IgE-Antikörpern führen diese zu einer verstärkten Freisetzung von Histamin und anderen Gewebshormonen. Dadurch entstehen eine allergische Reaktion und die begleitenden Beschwerden.

Food allergy vs. intolerance

Food allergies are to be clearly separated from intolerances. In an allergy, there is a reaction of the body's own defenses - the immune system. The reactions can be very severe, sometimes even life-threatening. In the case of an intolerance (also called intolerance), the body's own defense system is not involved. Due to a lack of enzymes, the body is not able to metabolize certain foods. Due to this disturbance of the body's own processes, complaints such as abdominal pain or flatulence occur.


Expertinnentalk über Allergien & Nahrungsmittelunverträglichkeiten

Unsere Ernährungsberaterin Mag. Kathrin Kittl war bei „push your limit“ zu Gast – dem Podcast, der Beine macht. Im Expertinnentalk mit der Sportwissenschafterin Elisabeth Niedereder dreht sich diesmal alles um die wichtigen Unterschiede zwischen Allergien und Unverträglichkeiten bzw. welche Tipps Betroffenen wirklich helfen können.

Primary food allergy

It is important to distinguish between primary and secondary food allergies. In a primary food allergy, the defense reactions are directed directly against a food. It usually occurs in early childhood. Common food allergies in children:

  • Cow's milk
  • egg
  • Soybeans
  • Wheat

Allergy in young children can heal spontaneously. About 80% of children are symptom-free by the time they start school. Especially in the case of cow's milk, hen's egg, soy and wheat allergies, there is a possibility that they will disappear over the years. Allergies to nuts, fish and crustaceans, on the other hand, unfortunately often last a lifetime.

Secondary food allergy / cross allergy.

Adult people usually react allergically to food due to an existing pollen allergy, triggered by a cross-reaction. Such a cross allergy occurs when the immune system mixes up the allergens, so to speak. The antibodies (IgE) are then directed against allergens in fruit or vegetables that are similar in structure to those of the primary allergy (the pollen allergy). Thus, many birch pollen allergy sufferers react to eating apples with an itchy mouth, swelling of the tongue or oral mucosa. The reason is the similarity of the apple allergen with the main allergen from birch pollen. This form of cross-allergy is therefore referred to as a "pollen-associated food allergy".

Overview of common cross allergies

Primary Allergy Cross Allergy
Tree pollen (birch, hazel, etc.) and grass pollen Pome and stone fruit, nuts, celery, raw potatoes
ragweed pollen (ragweed) banana, melons, cucumbers, tomatoes
Mugwort pollen carrots, celery, spices (cumin, parsley, coriander)
Dust mites shellfish (shrimp, lobster, shrimp, snails, crabs)
latex avocado, bananas, pineapple, chestnuts, kiwi, potatoes, tomatoes, buckwheat

Special care should be taken with allergies to nuts, fruits, vegetables and spices. These are becoming increasingly common and can cause severe allergic reactions.

Symptoms of food allergy

  • Swelling of the lips and face
  • runny nose tingling in and around the mouth
  • Stomach pain, cramps, diarrhea, vomiting
  • Itchy and reddened skin
  • drop in blood pressure
  • Allergic Shock (anaphylactic shock) Rarely - but if suspected, call 911 immediately!

Be careful with seafood for dust mite allergy sufferers.

Fisch, Erdnüsse und Früchte Quelle: Image Pont Fr/ - Copyright: Scientific DX GmbH, 2019

Especially the spring and summer time invites many people to enjoy freshly caught seafood. However, shrimp, squid, mussels and oysters can also trigger allergic reactions. In cases of severe hypersensitivity, even skin contact (without consumption) can cause severe symptoms, such as severe skin irritation or respiratory and circulatory problems. In the worst case, the effects can even be life-threatening (allergic shock). Since some allergens from dust mites have similarities with allergens from shellfish, people allergic to dust mites should be particularly careful when eating seafood.

Get clarity about your allergy.

Do you notice symptoms when eating certain foods? Then we recommend close observation (e.g. with a symptom diary) and the performance of an allergy test. These two pieces of information together are an optimal prerequisite for an in-depth consultation with an expert physician. When performing an allergy test, also make sure that cross-allergies can be detected.


This article has been reviewed by unserem Medical-Team for accuracy of content.

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