Oral Allergy Syndrome: Why Raw Fruit Can Make the Mouth Itchy

in Features, Fruit & Vegetable
Published: June 16, 2016

OASSummer is the season of fresh peaches, tomatoes, melons and more. Unless, that is, you live with oral allergy syndrome. Here are expert insights into the condition you’re just itching to control.

SUMMER is my favorite time of year. Nothing gives me that sense of reckless abandon like running barefoot through green grass and feeling the heat of the sun on my skin. And who doesn’t look forward to the cornucopia of fresh produce that the warm weather brings? That first juicy bite of a ripe peach; the satisfying crunch of a crisp carrot; the requisite snap of a newly picked snap pea. Is there anything to rival these summertime indulgences?

Alas, however, I must take vicarious satisfaction in watching others enjoy summer’s rich bounty. For me, a few tempting bites of certain fruits or vegetables will soon be followed with rather unpleasant sensations – a tingly throat, and an itchy mouth and tongue. The bane of oral allergy syndrome (OAS) strikes again!

OAS, also known as pollen-food syndrome, is a form of food allergy linked to certain raw fruits and vegetables, as well as nuts, and even seeds and spices. This syndrome that stops so many of us from enjoying nature’s harvest actually emerges because of allergies to the pollens of certain trees or grass or ragweed. For those with OAS, the immune system “sees” the proteins of some fruits and vegetables as being much like the pollen protein — and a cross-reaction ensues.

“It’s called a Class 2 food allergy,” says Dr. Anna Nowak-Wegrzyn, an associate professor of pediatrics and allergy at the Icahn School of Medicine at Mount Sinai in New York City. “You first become allergic to a pollen via inhalation, and then start reacting to foods that share similar proteins. So this food allergy is secondary to the pollen allergy.”

Birch tree pollen is a big offender. Nowak-Wegrzyn, who has researched the syndrome, says that anywhere from 30 to 70 percent of people with birch pollen allergy have OAS. “It’s a very common condition,” she says.

So how can you tell if you’ve got OAS, and know which ripe produce to avoid, which will be safe for the picking, and whether you might be susceptible to a more serious reaction? Let’s delve into the answers.

Dr. Anna Nowak-WegrzynDr. Anne Nowak-Wegrzyn

OAS Warning Signs

Symptoms of the syndrome can include itchy, tingly, scratchy or swollen mouth, lips, tongue, throat, palate or ears; watery, itchy eyes, runny nose and sneezing. They typically last only minutes to an hour. In my case, I will get the itch and tingle throughout my mouth – lips, tongue and throat, and thankfully, it usually dissipates in 20 minutes.

“There is a contact reaction in the mouth and throat of itching or swelling. It’s pretty immediate, but usually quite mild,” says Nowak-Wegrzyn. Fortunately, she adds that, unlike other food allergies, once an offending fruit or vegetable hits the stomach, “digestive enzymes break down the proteins and symptoms resolve.”

If you’re like me and sometimes crave a fruit fix, opt for cooked versions like apple sauce, peach cobbler or cherry pie. Unlike allergies where antibodies are created to specific foods, with OAS the thorough cooking will break down the proteins enough to keep some produce within reach.

Even though I have relatively mild OAS symptoms to raw foods, this doesn’t mean they aren’t bothersome. The one time I gobbled down an entire peach, my lips puffed up like lip fillers in overdrive. While some might envy such a look, it was wickedly uncomfortable, so I’ve not caved to temptation like that again.

What Foods Cross-React?

I never understood why some of the fruits that cross-react with birch pollen, like my beloved peaches, posed a problem while others, like pears and kiwis, I could eat to my heart’s delight. Dr. Antony Ham Pong, a Canadian allergist and researcher, has the explanation: “When you have a birch allergy, fruits have similar allergens, but not exactly the same. That’s why sometimes you may react to some foods and not to others.”

Foods like apples, peaches, carrots, celery and hazelnuts have a higher incidence of cross-reaction with birch protein. For those with grass allergies, fresh melons and tomatoes commonly set off OAS reactions, while melons, bananas and cucumbers can bring on oral symptoms in the ragweed-allergic.

OAS Cross-Reactors Chart

While the list of what foods and spices cross-react is especially long for those sensitized to birch pollen, the experts say that you only need to avoid the foods that trigger a reaction. However, Ham Pong says it’s important to be aware that over time, your OAS may progress so that you have more reactions to more foods.

Whether you have an OAS reaction can be affected by the season, the type of food, its ripeness and even what variety it is. For instance, Granny Smith and Golden Delicious apples may be more likely to set off an allergy, while Fuji, Braeburn and Santana are least likely. An unripened fruit often leads to a milder allergic reaction than one that’s very ripe.

This can make OAS tricky to diagnose. “It is far more common than we realize,” asserts Ham Pong. “Patients often don’t bring it up to their doctors because it doesn’t make sense. They get a reaction from eating an apple but not from apple juice so they think, ‘it can’t be an allergy’. They think they are crazy! Many people who have OAS ignore the symptoms because they are mild and inconsistent.”

Testing for Culprits

Both Ham Pong and Nowak-Wegrzyn suggest speaking to an allergist if you experience symptoms, since you likely need to be tested for IgE antibodies to pollens, as well as to the foods causing you trouble. (The experts say food testing should be performed with fresh raw foods as commercial extracts can result in false negatives.)

If you show positive results for certain foods, Nowak-Wegrzyn says you can take it a step further with component blood testing, a molecular diagnosis that measures specific IgE antibodies against pollen and implicated foods. This way, you’ll get a more reliable read on the severity of the allergy.

“If you only make antibodies against cross-reactive components in the food, it is extremely unlikely you would get a systemic reaction or anaphylaxis,” she says. “If you make antibodies against components that are specific to the food and not the pollen, then it’s more likely. It’s important to know, as it makes a big difference in how to manage the allergy.”

Next: Severe Cases of OAS + Cross-Reactors Chart