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Pollen-Food Allergy Syndrome (PFAS) versus Food Allergies

Pollen-Food Allergy Syndrome (PFAS), also called Oral Allergy Syndrome, happens when the body mistakes proteins in certain raw fruits, vegetables, and nuts for proteins found in pollen. Since these foods and pollen share similar proteins, the immune system reacts to both, causing allergy symptoms.


This condition typically begins in late childhood or adulthood, but generally not before the age of three. PFAS is often linked to seasonal pollen allergies (like hay fever), which tend to develop as children grow older. Symptoms are usually noticed once an individual becomes sensitive to pollen and then experiences “cross-reactions” (leading to physicial symptoms) when eating certain raw fruits, vegetables, or nuts.


Triggers and Associated Foods

Three common categories of pollen-triggered allergic symptoms and the associated foods are: 


  • Birch Trees: Almond, apple, carrot, celery, cherry, hazelnut, kiwi, peach, pear, plum, and potato

  • Ragweed: Banana, cucumber, melons, sunflower seeds, zucchini, and chamomile

  • Grasses: Celery, melons, oranges, peaches, tomato, and kiwi


Symptoms

PFAS happens when people eat certain raw (not cooked) fruits, vegetables, or nuts. Since these proteins are sensitive to heat, cooking or processing the food often changes them so they don’t trigger a reaction.


Symptoms of PFAS are typically mild and can include an itchy mouth or throat, hives on the mouth, or swelling of the lips, mouth, tongue, or throat. PFAS is triggered by cross-reactivity with pollen, only with raw foods, whereas a “true” food allergy causes the body to respond to specific food proteins (in any form). Symptoms can vary depending on the time of year, particularly with pollen activity. During times when the pollen is dormant–such as winter–individuals may experience few to no symptoms when consuming the related raw fruits or vegetables. However, during seasons when pollen levels are high, eating the same foods can trigger allergic reactions.


This fluctuation occurs because the immune system is already sensitive to the pollen during peak seasons, making it more likely to react to similar proteins in food.


PFAS and Food Allergies

PFAS is classified as a type of food allergy but is specific to the fruit or vegetable and the cross-reactivity of its pollen. While the likelihood of developing an anaphylactic reaction from PFAS is rare, it is possible. Individuals who feel they have had a reaction beyond the typically mild reactions seen in PFAS may have underlying allergies. For this reason, it is important to seek a proper diagnosis from an allergist/immunologist.


While it can be confusing and scary to experience any type of allergic reaction and symptoms, it is important to remember that these feelings are normal, and with proper care, living with PFAS can be manageable.


FUN FACT: I have PFAS to birch pollen (including all "stone fruits" - peaches, pears, plums, nectarines, apples, etc.) and several grass pollen-related fruits (including kiwi and celery). I am able to enjoy all of these foods cooked! (Thank goodness, because I LOVE apple crisp.)



References:

  1. Carlson, G., & Coop, C. (2019). Pollen Food Allergy syndrome (PFAS): A review of current available literature. Annals of Allergy, Asthma & Immunology, 123(4), 359–365. https://doi.org/10.1016/j.anai.2019.07.022 

  2.  Oral Allergy Syndrome | Symptoms & Treatment. ACAAI Public Website. https://acaai.org/allergies/allergic-conditions/food/pollen-food-allergy-syndrome/


  1. American Academy of Allergy, Asthma & Immunology. Pollen Food Allergy Syndrome (Oral Allergy Syndrome). Available at: https://acaai.org/allergies/allergic-conditions/food/pollen-food-allergy-syndrome/. Accessed October 11, 2024.


  1. Kim M, Ahn Y, Yoo Y, et al. Clinical Manifestations and Risk Factors of Anaphylaxis in Pollen-Food Allergy Syndrome. Yonsei Medical Journal. 2019;60(10):960. doi: https://doi.org/10.3349/ymj.2019.60.10.960


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