June 5, 2019

The Little-Known Oral Allergy Syndrome

As if being allergic to pollen isn’t frustrating enough, some people with hay fever (allergic rhinitis) also experience Oral Allergy Syndrome (OAS). This happens when the immune system mistakes the proteins found in some nuts and raw fruits and vegetables for those in pollen. When a person eats one of these foods, they experience mouth itchiness and/or swelling of the mouth, throat, lips, and tongue. OAS symptoms often worsen at the same time the allergenic pollen sees its seasonal peak.

The allergic reaction typically occurs immediately after eating or even inhaling airborne particles of the food. Symptoms are generally mild, which means many people just deal with the swelling and tingling without seeking diagnosis or treatment. They may continue eating the foods that trick their immune system into thinking a pollen attack is underway. It is rare for a patient with OAS to progress to having a full anaphylactic reaction.

Pollen allergies and OAS take years to develop, unlike many true food allergies that impact young children. Teens and young adults may find themselves suddenly having odd reactions to foods they have safely eaten their whole lives.

A huge range of raw fruits and vegetables (plus a few nuts) can cross-react with pollen. People who are allergic to ragweed may have trouble eating bananas, cucumber, melon, or zucchini. Those with grass allergies can experience symptoms after eating celery, tomatoes, peaches, oranges, peas, or melon. Birch pollen’s extensive list includes almonds, apples, carrots, celery, cherries, hazelnuts, peaches, peanuts, and kiwi. Interestingly, some patients report that only certain varieties of a fruit cause a reaction – for instance a valencia orange but not a navel orange.

Eliminating the troublesome foods entirely is the best way to solve the problem. Some people who just can’t quit some of their favorites report that cooking the fruits and veggies helps (The same does not always hold true for cooking nuts). Another trick is to avoid the skin of the raw foods because it contains a high concentration of the proteins that cause unpleasant symptoms.

If your four-year-old niece tells you she is allergic to all fruits and vegetables, she’s most likely angling to get out of finishing her dinner. However, people with pollen allergies really do seem to develop OAS out of the blue, rendering some favorite (and not-so-favorite) raw foods off limits.