April 6, 2009 — -- 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.
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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.
People with ragweed allergies might experience this reaction when they eat a banana, cantaloupe, cucumber, honeydew, watermelon and raw zucchini. Drinking chamomile tea, eating sunflower seeds or taking the herb echinacea might also provoke a response, since these are also in the same botanical family.
Grass pollen is related to substances found in melons, tomatoes, oranges, peaches and celery. And the pollen from alder trees might cross-react with apples, cherries, peaches, pears, celery, parsley, almonds and hazelnuts.
Not everyone with pollen allergies develops this hypersensitivity. Roughly 25 percent of people with a significant pollen allergy -- meaning their symptoms are sufficient enough to require medication to be comfortable during allergy season -- may experience oral allergy syndrome, Costa said.
And yet, a good majority of those with hay fever, or allergic rhinitis, as physicians tend to call it, are often unaware that this reaction to foods has any connection to their seasonal allergies.
Although the itchy mouth and throat can occur any time of year, the reaction might be more common or severe in spring and fall when there's more pollen in the air.
It's a form of contact hives in your mouth, explained Dr. Anna Nowak-Wegrzyn, a pediatric allergist at Mount Sinai School of Medicine in New York City. The reaction occurs when the food is in contact with your mouth, and it doesn't progress beyond that point.
Unlike food allergy symptoms, which tend to first be seen in infants and young children, food-pollen allergies typically occur in children who are a little older and in adults.
Allergist Dr. Harold Nelson, a professor of medicine at National Jewish Health in Denver, described oral allergy syndrome as a "localized allergy phenomenon," with its main symptoms in the mouth and throat. The plant proteins that trigger the allergic reaction don't survive the passage through the digestive system and get destroyed by stomach acids and digestive enzymes, he said.
In a food-pollen allergy, the primary problem is the pollen. In a classic food allergy -- say, to peanuts, or shellfish -- the main culprit is a protein found in the food itself.
If this foreign protein, known as an antigen, passes through the digestive system and gets absorbed, explained Nelson, the immune system reaction is a systemic or body-wide effect. That's why you may see symptoms, such as cramping, hives, diarrhea, and pain with a true food allergy.
The main question Nowak-Wegrzyn asks a patient who gets this cross reaction during pollen season is, "How uncomfortable does this make you feel?"
For some people, removing the peel from the fresh fruit or vegetable will do the trick. And in other cases, the freshly picked versions of produce may be better tolerated because storing the food increases the amount of allergen.
From time to time, experimenting with different varieties of the offending food -- say, an apple -- might not cause symptoms. Nowak-Wegrzyn doesn't tell people with food-pollen allergy syndrome to strictly avoid the food, but to trying it out of season or processing it differently.
She said getting allergy shots for hay fever seems to help oral allergy syndrome. Rinsing the mouth with water after eating the offending food may also dilute the protein on the mouth's surface.
As a pediatric allergist, Nowak-Wegrzyn occasionally finds herself reassuring parents that a child complaining of pollen-food allergy symptoms is not looking for a convenient excuse to skip the healthy fruits and vegetables.
"Sometimes, when I tell parents that the child is not making this up, they are relieved to know that this is real," she said.
And the syndrome, much like other kinds of allergies, tends to run in families.
"It's comforting to know that while food-pollen allergy syndrome is an annoyance and a nuisance, it's not likely to be life threatening," Costa said.
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