It’s bad enough that springtime can bring miserable allergy symptoms like itchy eyes, a runny nose and persistent postnasal drip, but more patients seem to be noticing that their pesky pollen allergies are accompanied by a whole other set of seemingly unrelated problems, including allergic reactions to many of the most popular fruits and vegetables — the healthy foods that we thought were supposed to help us!
While seasonal hay fever and food allergies aren’t associated in many people’s minds, there can in fact be a connection, I was told by practicing allergist Hannelore Brucker, MD, of the Southdale Allergy and Asthma Clinic in Minneapolis. Dr. Brucker began studying this phenomenon, called “oral allergy syndrome,” when she noticed that more of her patients were complaining about strange symptoms, such as an itchy mouth from eating a banana or hives on their skin from peeling potatoes. According to Dr. Brucker, pollen allergies affect about one in five people and, in her practice at least, about one-third of these unfortunate folks also are having allergic reactions to fruits and vegetables and some nuts and herbs.
It sounds mysterious, but there actually is a straightforward explanation as to why this happens. Chemically speaking, some of the proteins in pollen and certain fruits and vegetables (listed below) are very similar — Dr. Brucker calls them “crossover proteins.” Their purpose is the same — in pollens and in fruits and vegetables — these proteins help protect against pests that would harm the plants.
As we all know, in some people, the body manufactures antibodies to fight off seemingly benign substances (such as pollen) that it regards as foreign and intrusive. This then sets off a chain reaction that releases histamine, which starts inflammation and produces all those irritating symptoms that make spring and/or fall so very unpleasant for affected individuals.
What happens with oral allergy syndrome is that when susceptible people are exposed to pollen that irritates them (such as birch tree pollen from March through May… or ragweed pollen from mid-August to the first frost), their bodies not only build up antibodies but, over time, they also begin developing an allergy to the fruits and vegetables that have similar proteins.
For most people, the problem manifests itself as itching in the area of the lips, tongue and throat (hence the name “oral” allergy syndrome). This usually occurs within a few minutes of eating or touching the offending food and almost always vanishes quickly with no intervention — but, Dr. Brucker said, a small percentage of patients experience reactions that are extreme and dangerous, including constriction of the throat or, rarely, anaphylactic shock. If this happens, it is a medical emergency that requires an immediate trip to the hospital.
Heat (cooking) alters the chemistry of the proteins and makes them no longer problematic, so for the most part these reactions occur only with raw fruits or vegetables. Carrots and celery are frequent offenders, possibly because they often are eaten raw. Peeling potatoes also can make hands itch or produce hives or watery eyes in those who are sensitive.
According to Dr. Brucker, the stronger the pollen allergy, the greater the likelihood that you’ll have an oral allergy reaction. Time of year is also relevant since the various pollens are seasonal — if you are allergic to birch, you may be more allergic to its cross-reactive fruits and veggies in the spring, when you are having intense allergies. The reactions may vary among different strains of the same fruit and, as noted above, also will be affected by cooking.
If you are allergic to any type of pollen, now you know to keep track of any adverse reactions you get from eating fruits or vegetables… and then to consider limiting those foods, or at least eating them only cooked, not raw. For example, here is a list of foods from Dr. Brucker that are known to evoke oral allergy symptoms in people allergic to birch and ragweed…
Foods Reactive to Birch Allergy
Apples
Pears
Cherries
Peaches
Plums
Apricots
Carrots
Celery
Potatoes (raw)
Kiwi
Hazelnuts
Almonds
Foods Reactive to Ragweed Allergy
All melons including Cantaloupe (the most reactive), Watermelon, Honeydew
Cucumbers
Bananas
Zucchini
Chamomile tea
Echinacea (an herb)
A few other interesting facts:There is some indication that yet another common allergen — grass pollen — can lead to oral reactions, for example to tomatoes.
While many people have other types of food allergies, such as to peanuts, fish and shrimp, Dr. Brucker told me that these are completely different from, and not related to, pollen allergies and oral allergy syndrome.
If you’re thinking, “hmm… this itchy mouth stuff sounds familiar,” Dr. Brucker suggests you schedule an appointment with your allergist.
It’s smart to bring along the actual offending raw, fresh food so that your doctor can use it to do an easy skin-prick test, in which the doctor uses a needle to prick the fruit and then the patient’s skin and observes the reaction — a test that has the advantage of producing an immediate result that doesn’t require sending samples to a lab. (Note:Dr. Brucker said that some doctors use commercial fruit extracts for this testing, but since these products have been heated for sterilization, they may not produce a reliable result.)
And Dr. Brucker has one bit of good news for people who are allergy sufferers and also have oral allergy syndrome — the problem tends to fade away about the same time the pollen does.
