Nine-year-old Lilah Schwartz gets a funny reaction when she eats fresh cherries. And the same thing happens when she puts cantaloupe, carrots, celery and bell peppers in her mouth.
"My throat gets scratchy and starts to close up. And I feel like I can't breathe," said the fourth-grader from Hoboken, N.J.
As her mother recalled, Lilah had no problems eating these foods when she was younger. But not long after Lilah learned she suffered from hay fever, she felt uncomfortable whenever she ate certain fresh fruits and raw vegetables.
Yet, if the foods are cooked, Lilah can enjoy these very same foods without any problems at all.
This strange cluster of symptoms seen in hay fever sufferers when eating particular foods is called food-pollen allergy syndrome, or oral allergy syndrome. It's sometimes referred to as fruit-pollen syndrome -- although it's not just fruits that trigger the response.
Some people, like Lilah and her older sister, who have seasonal pollen allergies in response to common culprits such as ragweed, grass, alder, mugwort (a weed) or birch, might get an allergic reaction shortly after they eat certain foods.
"You may get itching of the lips, the inside or roof of the mouth, and the back of the throat," said Dr. John Costa, director of allergy services at Brigham and Women's Hospital in Boston. "It happens almost immediately."
Other symptoms of oral allergy syndrome include a tingling in your mouth, an itchy tongue and throat and lips that feel swollen (although they usually appear normal).
"This reaction lasts anywhere from 10 minutes to half an hour," said Costa.
So, what's happening? Evidence suggests that in these cases, the immune system mistakes a plant protein in the fruit, vegetable, nut or seed for pollen, and this irritant triggers what allergy specialists call a cross-reaction.
When you eat a fresh apple, for example, your mouth thinks it's been exposed to birch pollen, Costa said. There's a protein in the food that shares a similar structure and shape to the pollen-related protein and sets off a quick, short-term reaction that's largely confined to the mouth and throat.
The hallmark of food-pollen allergy syndrome is that the exact same fruits and vegetables that trigger these symptoms when the food is eaten raw can be eaten without any of these effects when the food is consumed cooked, said Costa.
So, while a taking a bite out of a fresh apple -- whether it's organic or conventionally grown -- might cause itching in the mouth and throat in some people, the same individuals could eat a slice of apple pie, spoon up some apple sauce or drink a glass of apple juice and be fine. It's also unlikely that apple jelly or dried apples would cause a problem.
Only the fresh food causes the reaction and not the cooked, baked, microwaved, canned or processed forms -- all of which suggests that cooking or heating destroys the allergenic proteins in the food.