Overview:
The oral allergy syndrome, also known as class 2 food allergy or the pollen-food syndrome, is a type of cross-reaction to food that occurs in people with allergies to common pollens. People with oral allergy syndrome (OAS) may experience allergy symptoms when they eat fruits or vegetables with pollens similar to those in the plants whose pollens they are allergic to.
Major Symptoms:
The major symptom of oral allergy syndrome (OAS) is itchiness and tingling of the mouth, lips and throat. Some people with the oral allergy syndrome may also experience angioedema -- redness and swelling -- of the mouth, lips and face. Many people with oral allergy syndrome have hay fever, or allergic rhinitis, due to pollen allergies.
Foods and Pollens Associated with OAS:
- Birch pollen allergies are associated with apple, carrot, cherry, pear, peach, plum, fennel, walnut, potato, spinach, buckwheat, peanut, honey, celery, and kiwifruit.
- Japanese cedar allergies are associated with melon, apple, peach, and kiwifruit.
- Mugwort allergies are associated with celery, carrot, spices, melon, watermelon, apple, hazelnut, and chestnut.
- Grass pollen allergies are associated with melon, tomato, watermelon, orange, and cherry.
- Ragweed allergies are associated with melon, chamomile, honey, banana, and sunflower seeds.
Cooked Foods and OAS:
The proteins that cause OAS are heat labile. This means that when they are cooked, they lose their ability to cause the unpleasant reaction. It's common for someone whose mouth tingles and whose lips swell a bit every time they eat raw apples to be able to eat applesauce with no problems.
Complications:
While many OAS reactions are mild, OAS can rarely cause anaphylaxis. Therefore, if you've experienced OAS symptoms, you should contact your doctor about allergy testing. You will need to avoid any raw fruits and vegetables that can trigger your symptoms, though you should be able to eat them in cooked form.
Living with OAS:
There are three major aspects to living with oral allergy syndrome: avoiding raw fruits and vegetables that can trigger symptoms, keeping allergic rhinitis symptoms under control, and potentially, allergen immunotherapy for pollen allergies.
Once you've identified your potential OAS triggers you'll need to avoid them in their raw state. Vegetable trays, fruit salads, iced tea sweetened with honey, honey-covered baked goods, and pesto sauces (herbs) are among the types of foods that can trigger OAS symptoms if you're sensitive to one of the ingredients.
Your allergist may prescribe antihistamines or other medications for allergic rhinitis symptoms year-round or at the height of pollen season. Many people find that their OAS symptoms are worst when the corresponding pollens are in the air, so be especially careful to avoid the offending foods during these times.
Finally, allergen immunotherapy to the pollens related to your food allergens has had a mixed record of success in studies with respect to helping reduce sensitivity to food allergens related to OAS. You may wish to discuss the pros and cons of this therapy with your allergist.
Sources:
Adkinson, N. Franklin, et al., ed. Middleton's Allergy: Principles and Practice. 6th Ed. Philadelphia: Mosby, Inc., 2003. Cox, Linda, et al. "Allergen Immunotherapy: A Practice Parameter Second Update." Journal of Allergy and Clinical Immunology. Sept. 2007 120(3 Suppl): S25-S85. Kinaciyan, Tamar, et al. "Successful Sublingual Immunotherapy with Birch Pollen Has Limited Effects on Concomitant Food Allergy to Apple and the Immune Response to the Bet v 1 homolog Mal d 1." Journal of Allergy and Clinical Immunology. Apr. 2007 119(4): 937-43.
