In most people, OAS is a relatively mild allergic response, and people who have it can eat the vegetables or fruits that cause inflammation and itchiness in their throat and mouths – as long as those foods are cooked.

The reason for this? OAS sufferers are only allergic to the “heat labile proteins” – the proteins in the fruit that get destroyed once exposed to heat.

This explains why the symptoms are confined to the mouth: “When you eat the fruit raw, it’s your own body’s heat that breaks down the protein, which is why the reaction doesn’t move beyond the mouth,” says Dr. Paul Keith, an associate professor of allergy and clinical immunology at McMaster University in Hamilton, Ontario.

So while a raw apple a day might keep the person with OAS away, she can eat a slice of apple pie without a problem. The same goes for vegetables. While celery or carrots and dip may make your lips puff up, a nice hearty vegetable soup will go down smoothly.

There are some tricks you can use to try to cheat nature – but they may not work for everyone. Dr. Bruce Mazer, director of the division of allergy and immunology at the Montreal Children’s Hospital and associate professor at McGill University in Montreal, suggests microwaving the fruit, like an apple, for a few seconds.

He also suggests sprinkling lemon juice on the raw fruit and letting it sit for a few minutes before eating. These tricks may help to break down those heat labile proteins while still allowing the fruit to be somewhat crisp. You can also simply try peeling the fruit first since most of the fruit’s proteins are in its peel. Of course, this would only help for fruits that have a peel and not for fruits like raspberries and strawberries.

Dr. Keith approaches management from a different angle. He suggests trying to better control the hay fever so that your body will no longer recognize the offending proteins, even in the related fruits and vegetables. This can be done by using saline nasal sprays to keep the nose clear, wearing glasses to protect the eyes, and keeping windows and doors closed to lessen exposure to pollens.

A less severe form of food allergy, called oral allergy syndrome, is a reaction to proteins in common raw fruits, vegetables, nuts and seeds. It’s called “oral allergy” syndrome or OAS because its symptoms are usually limited to the lips, mouth, tongue and throat.

Estimated to affect about one-third of pollen allergy sufferers*, oral allergy sydrome (sometimes called pollen allergy syndrome) is more widespread than the higher profile – and more dangerous – allergies to peanuts, dairy and eggs.

If you have oral allergy syndrome, chances are that you also have allergies to pollen from trees such as birch and alder, and/or to pollens from ragweed and grass.

Think of it as an allergy by association – or a cross-reaction – because your immune system, already primed to attack tree, plant and grass pollens, does not recognize the subtle differences between their proteins and those contained in foods as basic as an apple.

Not Usually Life-Threatening

One reason for oral allergy syndrome’s lower profile is that, unlike other food allergies, its symptoms are not usually life-threatening. Another is that it is relatively easy to avoid.

“You may eat something that contains traces of peanut, dairy or egg, but you aren’t going to unknowingly bite into a raw apple,” notes Dr. Antony Ham Pong, an allergist and based in Ottawa.

High Incidence of Oral Allergy Syndrome

About 10 per cent of the population**, or roughly one-third of North Americans with pollen-related allergies, are thought to be affected by OAS.

Ham Pong says he usually first sees patients when they’re between 8 to 10 years old. It’s not clear, however, why no more than one-third of hay fever sufferers are affected.

Next: More Serious Oral Allergy Symptoms

WE CAN blame the deciduous trees’ attempts at procreation for our watery, red-eyed snuffling and other springtime rhinitis symptoms. Catkins, which often appear as elaborate cones or buds, are a tree’s reproductive organs, and they bloom before the leaves bud. Male catkins will release literally millions of pollen grains into the air in an attempt to find a female catkin match.

Dr. Wilf Nicholls, director of the Memorial University of Newfoundland Botanical Garden, explains that wind pollination is “super inefficient” because only a fraction of the huge amounts of tiny grains the tree churns out will arrive at their intended destination, the female catkin. Instead, great quantities of them will be inhaled into noses and throats and set off reactions in the tree allergic.

It’s an unlucky break that most deciduous trees in northern climes are wind-pollinated. Birch, elm, maple, oak and poplar are some of the most allergenic trees across Canada and the northern United States. But where you are, the month and the weather all influence the onset of symptoms.

West Coast

On the foliage-rich west coast, red alder is public enemy number one. Robert Guy, head of forest sciences at the University of British Columbia, says much of the forest surrounding coastal towns and cities is full of red alder. Depending on the weather, these trees can pollinate as early as mid-February, or as late as the end of March, and they spread pollen for about three weeks.

Vancouver allergist Dr. Donald Stark says red alder is particularly insidious because it produces a ton of pollen; it often has the highest pollen count of any plant on the coast. People allergic to it may also react to birch trees, which pollinate about a month after alders, prolonging the misery.

Stark identifies the Garry oak as another culprit on the west coast.
In most of Canada, ragweed is the worst offender for triggering hay fever, followed by grass, then trees. Stark says the west coast is the exception: here, trees pack the hardest punch.

Next: Traveling Eastward

Little did I know then that 25 years later, grass, trees, ragweed and dust would become my sworn enemies. I was about 32 years old when the grass and ragweed allergies set in. I’d had some small rashes, then one day after playing soccer with my young sons, I was relaxing in the grass. Soon, there was an angry rash on the back of my legs that extended from the underside of my calves right up my thighs.

I had skin-prick tests and was given a long list of allergens that I had reacted to. Soon after, I started a course of allergy shots. With the weekly needle and a daily antihistamine, I fared pretty well. After about six years, I decided that the immunotherapy had done what it could – my allergic responses had been cut in half – and I stopped taking the shots. July and August remained fairly enjoyable as long as I kept up the antihistamines.

Then, in the summer of 2003, my allergies took a turn to life-threatening. One evening, I was enjoying some almonds as an after-work snack when a series of symptoms rapidly developed. Suddenly, I was sneezing, my eyes were unbearably itchy, my mouth itched as well, my tongue grew thick and I had trouble swallowing and breathing.

My husband and oldest son were at work, and my younger son was out golfing. So I drove myself to the Port Colborne Hospital about 10 minutes away. At Emergency, I was whisked in and quickly given shots of both epinephrine and antihistamine. My ears were so swollen that I could barely hear the nurse and one eye had puffed shut. The experience was downright terrifying. My symptoms subsided after about two hours.

My family doctor later prescribed an EpiPen and referred me to an allergist. It turned out that my allergies had blossomed (if you’ll pardon the expression) into Oral Allergy Syndrome. This form of allergy occurs when the immune system of a person allergic to a pollen cross-reacts to proteins in fruits, nuts and vegetables from related plant families.

My anaphylactic reaction to almonds was linked to my allergy to birch pollen, while my grass allergy set off reactions to a long list of vegetables and fruits. I had to say goodbye to oranges and melons, (including watermelon), tomatoes and kiwi. My immune system’s intolerance of ragweed affected yet another group of food: there are no bananas, zucchini or cucumbers any more for this girl.

People ask, do you still look forward to summer? Of course! However, the season requires planning. Open windows are not an option for me; we have central air conditioning now. While I love to hang laundry outdoors, that has become a no-no as pollen gets caught in fabrics. I can’t cut the grass, nor even sit on the green stuff. If I go on a picnic or relax outside, a blanket is my best friend.

Planning also means nasal sprays, eye drops and a daily antihistamine. Once I’ve sprayed, droppered and swallowed, out I go, enjoying all the Canadian summer has to offer. I also take all the precautions: reading labels on all foods I eat; asking lots of questions of servers at restaurants. I live every day at every meal by the motto, “when in doubt, go without.” And I’m fortunate to have wonderful, supportive family and friends.

There are times when not being able to eat all of the fresh fruits and veggies I once enjoyed gets me down. But I am thankful for the few that I can eat and, yes, I have been known to hog my strawberries. So when you’re outside on a hot day this summer, enjoying a juicy piece of watermelon and wiping off your chin, think of me and remember how lucky you are.

Carolyn Purnell lives on the property she grew up on near Port Colborne, Ontario.

First published in Allergic Living magazine.
© Copyright AGW Publishing Inc.
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AS FRIENDS herald spring’s arrival with the glee of a lottery winner, it’s often hard for the allergic to join the celebrating. They know that their tree foes – birch, elm, maple, alder, poplar and their nasty ilk – have begun to churn out clouds of tiny allergy-causing pollen.

Not only do a third of us battle hay fever – with runny noses, sinus and eye symptoms – but for a significant proportion of allergy sufferers, the spring bloom is just the start of their allergy woes. Dr. Antony Ham Pong, an Ottawa allergist and clinical researcher, estimates that up to 10 per cent of the general population has a condition called oral allergy syndrome, or OAS.

It’s a less severe form of food allergy, directly related to pollen reactions, that’s known to set off tingling and unpleasant itching in the mouth, throat and lips. Reactions are caused by a variety of fruits, vegetables, nuts, seeds, and even spices; all of which share allergenic proteins with specific hay fever-causing trees and plants.

“Nobody talks about the foods causing oral allergy syndrome because it’s not considered a life-threatening allergy,” says Ham Pong, the author of several articles educating patients and doctors about oral allergy syndrome. “But it’s actually more common than peanut, milk, egg, and fish allergy.”

In springtime, two of the biggest cross-reaction offenders are birch and alder trees. Depending on where you live, anywhere from 20 to 70 per cent of people who are allergic to birch and alder pollens will also have oral allergy syndrome.

Ham Pong estimates about a third of birch-allergic North Americans are affected, but the incidence of oral allergy syndrome is even higher in some European countries. Although OAS is relatively common, he doesn’t think it is increasing, at least not in North America. Rather, doctors have become better at spotting this condition.

But how can a tall, skinny tree that gives you the sniffles cause an itchy mouth if you chew on a celery stick?

Next: How the immune system gets confused

A life with OAS means only cooked or baked fruit. Crisp, raw fruit, how I miss you.

Cradling a fresh, succulent peach in my hands, I take in its tantalizing aroma. I rub the fuzz lightly on my lips before taking a big, juice-dripping bite. Delicious.

I swallow, and the tingling begins. First on my tongue, then throughout my mouth and my throat. Tingling becomes itching: there is no stranger feeling than an itchy tongue. That bane of the fruit-loving, Oral Allergy Syndrome, has kicked in.

OAS (also known as pollen-food syndrome) is an allergic reaction to certain proteins in a variety of fruits, vegetables and nuts. The symptoms include itching and burning of the lips, mouth and throat. In more serious reactions, there may be swelling of the mouth, back of the throat and windpipe as well as hives.

Those of us with the condition usually develop symptoms within minutes of eating the food, and they typically dissipate in less than 15 minutes. Just enough time to make a person go a bit crazy.

For me, the itching can be counteracted by eating a neutral substance such as bread or by drinking water. Fortunately, OAS is rarely severe.

“For the majority of people, this is not a real life-threatening problem like true food allergies,” explains Dr. Bruce Mazer, director of the division of allergy and immunology at Montreal Children’s Hospital and an associate professor at McGill University.

Raw vs. Cooked
OAS sufferers react to raw fruit, but are usually able to eat the same food cooked without a problem. “Typically we see OAS in people allergic to heat labile protein, which means those proteins easily destroyed by heat,” explains Dr. Paul Keith, an associate professor of allergy and clinical immunology at McMaster University in Hamilton.

“When you eat the fruit raw, it’s your own body’s heat that breaks down the protein, which is why the reaction doesn’t move beyond the mouth, says Keith, who’s also an investigator for AllerGen, the allergy research network.

I know the raw versus cooked issue first-hand. When I eat uncooked fruits like apples, cherries, pears and my beloved peaches, they all cause itching. But bake them in a pie and I can eat to my heart’s content, without so much as a tingle.

I remember eating apples as a youngster with no problems, but then one day, my tongue got really itchy afterward. As my mother couldn’t see anything on my tongue, she assumed I was trying to get out of eating the fruit. Then it happened again, and with different fruits. Because they couldn’t see a problem, my parents thought I was just fussing. But they did stop giving me the troublesome fruits.

By my late teens, I started trying these fruits again, in small amounts. Sometimes I got an intense itch in my mouth and throat, sometimes it was minor. If I craved the juicy goodness, I’d eat the fruits anyhow – since the itch always went away.

Once, however, I ravenously ate a whole peach. This time itchiness turned to swelling: my lips got puffy and I felt like I couldn’t swallow. The episode subsided in half an hour. I was miserable, yet vindicated, since my parents finally believed there was an allergic reaction. We asked a couple of doctors, but no one could pinpoint the condition. They advised that I avoid the offending fruits like any major food allergy, and that put an end to my fruit infatuation.

Fortunately, awareness of OAS is growing. But how can you be sure if you have it?

Next Page: Diagnosing OAS