The Allergy Condition That’s Fooling Patients Into Giving Up Guacamole, Melons & More

by | Aug 17, 2022


Years before Dr. Amanda Trott-Gregorio found a passion for allergy and asthma, she fell in love … with an avid gardener.  It was no secret that the guy she met while in medical school enjoyed the comfort and simplicity of a sprawling fruit and vegetable garden. But what Dr. Trott didn’t know at the time was how connected what they would grow in their own Stone Oak area garden one day might be to her work as an allergist.

Some fruits and vegetables, like many of those grown today by Dr. Trott-Gregorio and her husband, are blamed for a food allergy.
“I have had patients who come in to Juniper Allergy concerned about what they suspect is a an allergy to a certain fruit or vegetable,” Trott-Gregorio says.  “But when we test the patient the result is negative for food allergy.”
Turns out, what the patient thinks is an allergy to a certain fruit or vegetable is a condition called Oral Allergy Syndrome. 
The two are commonly confused, according to Dr. Trott-Gregorio.
Oral Allergy Syndrome is caused by cross-reacting allergens found in both pollen and raw fruits, vegetables, or some tree nuts.  The immune system recognizes the pollen and similar proteins in the food and orders an allergic response to it.  
A classic example is the ragweed – melon, banana, and avocado cross-reactivity.  Structurally, the protein in ragweed is very close to that of the food. 
“The immune system in your mouth, especially the area in the inner cheeks, thinks that you’re eating a bunch of ragweed,” says Dr. Trott-Gregorio.  As a result, the person may feel itchy in the ears of develop hives on the mouth.  Swelling of the lips, mouth, tongue, and throat have also been reported with oral allergy syndrome.  But it won’t cause a person to go into anaphylactic shock.  
Even better, oral allergy syndrome can be treated-in a round-about way.
“We’ve found that by treating a patient for the cross-reactive pollen allergen the symptoms caused by the culprit food usually stop occurring,” says Dr. Trott-Gregorio. 
Another treatment option is to simply avoid the food if it causes intolerable symptoms.  
Other allergens that tend to have cross-reactive properties are birch and grass pollen.  Birch pollen shares a similar protein structure with apple, almond, carrot, celery, cherry, hazelnut, kiwi, peach, pear, and plum.  Those allergic to grass pollen may be bothered when they eat celery, melons, oranges, peaches and tomato. 
“Oral Allergy Syndrome is an interesting allergy and immunology phenomenon,” Dr. Trott-Gregorio says.  One, the allergist and mom of two tends to think about with each fruit and vegetable harvest her garden-loving family of 4 collects – right from their own backyard. 
“There’s little better than helping someone enjoy guacamole or any number of favorite fruits or vegetables again!”