They say that “an apple a day keeps the doctor away.” But for some people, the result is just the opposite. If you’ve ever bitten into an apple and felt your lips and mouth itching, tingling, stinging, or swelling, you may have a condition known as oral allergy syndrome (OAS).
OAS is the result of an allergic reaction to a particular pollen. In nature, each pollen is different and comprised of a unique set of proteins called allergens.
If a person is sensitive to that allergen, he or she will have an allergic reaction. Surprisingly enough, some fruits contain a similar combination of proteins, and, if the same person bites into one, he will also have a response (albeit slighter and shorter lasting).
Apples share similar proteins to the allergens found in birch pollen. The shared allergic response is called cross-reactivity. Other fruits, vegetables, spices, and nuts have similar cross-reactivity to pollens, such as:
Birch and celery
Birch and almond
Birch and garlic
Cypress and peach
Mugwort and peach
Mugwort and bell pepper
Mugwort and coriander
Orchard grass and tomato
Ragweed and melon
Ragweed and cucumber
More than 50 percent of people with birch pollen allergies will react to raw apples. However, if the apple is cooked or processed—as it would be in applesauce or pie—many of those proteins will be broken down. When this happens, the apple will no longer be recognized as an allergen, and there will be no allergic response.
The same applies to any other fruits, vegetables, spices, or nuts with known cross-reactivity. Choosing an organic or non-organic product makes no difference in whether an allergy will occur.