Why Does Eating Raw Fruit Cause an Allergic Reaction?

Published: July 12, 2018
Photo: Getty

Q: I’m 16 years old and figured out last year that I’m allergic to fruit – l ate a peach and my throat felt like it closed up and I had trouble breathing. After a while, it went away and my mouth was just tingling. Since then, I’ve gotten slowly allergic to many fruits. But l can eat them cooked without a problem. What is it about raw fruit that makes me have these reactions?

Dr. Sharma: Your reactions to fruit sound consistent with oral allergy syndrome (OAS), also known as pollen-food allergy syndrome. In OAS, a person with a prior history of a pollen allergy develops allergic symptoms, such as itching and/or mild swelling of the mouth, lips and throat, when eating certain raw fruits and vegetables. The chemical structure of the raw fruit or vegetable is very similar to the pollen triggers, which the immune system is already primed to defend against.

In your case, the peach allergen is very similar to birch tree pollen allergen. As a result, the immune system “sees” the raw fruit and vegetables as the pollen triggers and local allergy symptoms follow. As you have found, cooking these fruits or vegetables often breaks down the proteins, making them less allergenic.

In most cases of OAS, symptoms are confined to the mouth and throat – and rarely escalate to more widespread reactions. A review of several studies involving a total of more than 1,300 OAS patients found fewer than 10 percent had widespread symptoms outside of the mouth, throat or gastrointestinal tract, and only 1 to 2 percent experienced anaphylaxis.

In your case, you should seek advice from an allergist because you experienced a sensation of throat closing and trouble breathing after eating the peach. When more serious reactions occur to a raw fruit or vegetable, an allergist may advise you to be careful to avoid that raw fruit or vegetable and to carry epinephrine auto-injectors.

Dr. Sharma is an allergist, clinical researcher and associate professor of pediatrics. He is Chief of the Division of Allergy and Immunology at Children’s National Medical Center in Washington D.C. and Director of the Food Allergy Program. He co-authors “The Food Allergy Experts” column in Allergic Living magazine. Questions submitted will be considered for answer in the magazine.

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