A Look at Food Allergies: The Newly Discovered Oral Allergy Syndrome (Part 3/4)

Oral allergy syndrome affects many people who don't even know they have it. In fact, many doctors haven't even heard of it. Until recently, it has not been widely recognized or even taught in medical school. Some sources say that it's the most common type of food allergy in adults.

I first had this when I was eating watermelon one summer in middle school. I had no problems with watermelons previously, but that day, my mouth and throat became itchier the more I ate. Plus, the food started to taste blah, and my stomach didn't feel well. So I stopped eating and retested the next day. The same thing happened and went away within 30 minutes. I didn't have any again until a few summers later and I was fine that time. It was extremely strange to me, but very real. My mom thought I was nuts, and I couldn't find any information about watermelon allergies. (It was in the dark days before the Internet.) Since then, I have felt the same way on occasion with apples, nectarines, cherries, and pears. If it's really bad, the itchiness extends into my ears from the inside (via the Eustacian tube). Now that's an itch you really can't scratch. Very uncomfortable. But I don't have any problems during the winter with these fruits. Plus, I would be fine with eating the cooked version of all of these fruits.

In residency, I looked into this issue further and finally found a source that explained why. It's called oral allergy syndrome, and it's related to my other allergies. My symptoms are pretty much everything that is described in the books. I'm highly allergic to Birch tree pollen and Ragweed pollen. Birch tree pollen cross-reacts with carrots, celery, apples, cherries, nectarines, peaches, pears, almonds, hazelnuts, parsnips, and potatoes. Ragweed cross-reacts with bananas, cantaloupes, honeydews, and watermelons. I'm not allergic to grass, so I've never had a problem with kiwi or tomatoes. There are other documented relationships, but these are the most common. Please see the chart at the bottom.

Oral allergy syndrome is caused by proteins in the raw fruit or vegetables that resemble the particular pollen protein. You are not actually allergic to the fruit or vegetable normally, but your body's antibodies are on high alert and are easily confused during peak season for that particular pollen. Once your allergic responses start to attack the birch pollen entering your nose, it goes to war with anything that resembles birch pollen, including particular proteins in cherries and peaches. When cooked, those proteins change and no longer cause the oral allergy syndrome.

This past spring, which is peak time for birch tree pollen, I couldn't eat some organic apples I had just bought. I was so disappointed. But then I remembered that I can still eat them cooked, so I made maple syrup-glazed pork chops with apples.

Although uncomfortable, the symptoms probably do not lead to worsening allergies. The research community has different opinions on just how serious this syndrome is. If you ignore the symptoms and continue eating, anaphylaxis is possible according to some sources. I can't imagine continuing to eat. After the first bite, I know immediately that it's not right. Trying to eat a second bite is just not worth the itchiness and discomfort I feel. Any foods I try to eat after this syndrome starts just doesn't taste the same, even if I'm hungry. Oral allergy syndrome seems to happen with only 1-2 fruits at a time for me, and it varies through the seasons. Earlier this year, I couldn't eat cherries. A month later, I couldn't eat nectarines. But right now (late summer), I can eat pears and apples. The feeling is so unpleasant and immediate that I couldn't bring myself to try cherries or nectarines again this summer. Perhaps I'll try again if they are on sale in the winter.