Explaining Oral Allergy Syndrome or Pollen Food Syndrome.
Do you ever get itchy mouth with certain fresh fruit, raw vegetables, or raw nuts? Have you noticed it’s not always consistent and sometimes you can eat the same food without symptoms or if it is well cooked there’s no oral itch? Welcome to oral allergy syndrome or “OAS”. Many people think this is a food allergy but that’s not always the case so we always suggest seeking the advice of a board certified allergist to answer your specific questions.
What is OAS vs. a systemic food allergy?
OAS/PFS symptoms are limited to the mouth, lips, and throat and resolve without treatment. Food allergy or systemic anaphylaxis symptoms go beyond the mouth and can involve the skin, lungs, GI tract and require an epinephrine injection to treat. Both reactions are caused by proteins in the food but systemic anaphylaxis is much more severe. It is important to have these symptoms evaluated especially with peanut or treenuts as an itchy mouth may be the first symptoms of a much more severe reaction. Allergy skin tests for food and or allergy blood test may be done to better assess.
What causes OAS?
OAS is caused by cross reacting allergens found in pollen, raw fruit, raw vegetables, and raw tree nuts. Another name is pollen food syndrome (PFS) because the actual reaction is due to an allergy antibody (IgE) against pollen and this pollen “looks similar” to proteins in the food. Basically your immune system is tricked and thinks you are eating pollen. These symptoms are most common in individuals with seasonal allergies.
Which foods cross react?
Birch: Apple Almond Carrot Celery Cherry Hazelnut Kiwi Peach Pear Plum Peanut Soy
Ragweed: Banana, Cucumber Melons Zucchini
Grass: Celery Melon Orange Peach Tomato White Potato
Why do the symptoms disappear when the food is cooked?
Exposing these foods to high temperature causes the proteins to “denature”. Basically the protein changes its shape and no longer “looks like the pollen”. Your immune system is no longer confused and no longer thinks you are eating pollen.
If you have additional questions about food allergy, OAS, and PFS give us a call and make an appointment
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