Oral Allergy Syndrome

Is that juicy, ripe apple making your mouth itch?

Oral Allergy Syndrome

Hay fever doesn’t just cause sneezing and congestion. Some may also get an itchy mouth or swollen lips when foods associated with pollen allergies, such as raw apples, peaches, and almonds, are eaten. But there may be ways to enjoy these foods again.

As a child, I never gave a second thought to food, except when I was hungry—or didn’t want to eat the veggies on my plate. That changed over the years, as I began to notice problems after eating many common foods. It turns out I’d developed an allergic reaction to some of my favourite foods.

Foods caused reactions

It started with raw apples when I was 12. Right after biting into them, my lips, tongue, and gums became itchy. After repeatedly having the same reaction, I stopped eating apples entirely. The irritation occurred again, though, when I ate other fresh fruits such as pears and cherries. How could so many foods make me react this way?

The topic came up in my office one day when a colleague offered me an apple slice and I told her I couldn’t eat it. I expected the usual doubtful looks, but instead, another co-worker asked, “Are you allergic to pollen?” When I nodded yes, she said, “You probably have pollen-food allergy.”

Of course, I immediately looked this up online. Seeing a list of foods I was unable to eat tied to a specific condition, called pollen-food syndrome or oral allergy syndrome (OAS), gave me a sense of relief. I finally knew what had been bothering me all those years.

Mystery solved

Dr. Paul Keith, associate professor of clinical immunology and allergy at McMaster University, says that when you have hay fever, “you’ve made IgE [antibodies] to a protein in pollen that you inhale through your nose, and that protein is also present in different plant foods. So if you’re allergic to tree pollen, you may react to peaches, because they’re a tree fruit and have the same protein.”

The American College of Allergy, Asthma & Immunology (ACAAI) lists some foods commonly associated with pollen allergies:

  • birch pollen—apple, almond, carrot, celery, cherry, hazelnut, kiwi, peach, pear, plum
  • grass pollen—celery, melons, oranges, peaches, tomato
  • ragweed pollen—banana, cucumber, melons, sunflower seeds, zucchini

The onset of OAS is more common in older children, teens, and young adults. Keith points out, though, that not everyone with hay fever has OAS, and sufferers don’t react to all of the foods listed.

Symptoms

According to the ACAAI, symptoms of OAS include itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat, and they subside quickly after contact. It’s considered a mild form of food allergy, and severe reactions like anaphylaxis are quite rare.

Since the proteins in these foods that cause the reaction are sensitive to heat, most people with OAS can eat the same foods cooked without having irritation.

Managing OAS

  • Avoid trigger foods.
  • Peel fruits.
  • Cook or microwave trigger foods.
  • Take vitamin D3 supplements, or get more in your diet.
  • Close windows during pollen season.
  • Use a nasal filter device.
  • Use saline nasal spray or neti pot.

Ways to cope

Since people with OAS tend to know what their food triggers are, Keith says they should avoid them, or in the case of fruit, try peeling them. He explains, “There’s less fresh protein in the pulp of the apple than there is in the peel.” This may help get rid of most of the offending protein, leaving you with less chance of a reaction.

Cooking these foods might also help. “Usually people who have the mild allergy to raw peach, for example, have no problem eating a peach pie, and some people heat their apple in the microwave for 30 seconds and don’t have a problem,” Keith says. “For other people, though, that still isn’t enough.”

Controlling hay fever

Keith says treating a person’s hay fever may also be beneficial. He recommends keeping windows closed during pollen season and taking vitamin D3 or getting more of it in your diet.

In addition, Keith suggests using a nasal filter “so you don’t inhale the pollen [connected to your OAS allergens].” He also suggests a saline nasal spray to “wash out the pollen from your nose.”

Year-round problem

While pollens associated with OAS are in the air from spring to early fall, OAS can occur at any time of year. Knowing what causes your symptoms and how to work around their cause, though, might help you to once again enjoy some of your favourite foods. 

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