Oral Allergy Syndrome, or OAS, is one of the most common allergy types in adults, yet many affected individuals may not even be aware of it.
OAS is characterized by a reaction that affects the mouth and throat area after direct contact with raw fruit and vegetables. This generally occurs in individuals with an existing allergy to pollen. The connection between the food and the pollen is explained by allergen cross-reactivity, in which the proteins in a fruit or vegetable are similar to those in a specific type of pollen. The immune system recognizes both protein types as the same and, if the individual is allergic to that particular type of pollen, it initiates an immune response in the local mouth/throat area.
What does OAS feel like?
Allergy symptoms of OAS include swelling of the lips, mouth, tongue, or throat, an itchy mouth, a scratchy throat, and even sometimes itching in the ears. Only plant-based foods (and generally only raw forms) trigger OAS symptoms. Meat, seafood, and dairy products do not cause OAS symptoms.
How do I know if I have OAS?
Although there is no test for diagnosing OAS specifically, symptom histories, skin prick or blood tests that come back positive to a certain pollen type, or even oral food challenges can help identify OAS. An oral food challenge is a medical procedure that involves eating the suspected food(s) in gradually increasing amounts under medical supervision. Rare cases of OAS may lead to anaphylaxis, so take precautions if reactions are extreme. Any OAS-like reaction to nuts or peanuts should also be treated with care, as this could signal a true food allergy, which can be life-threatening.
What if it’s my favorite food?
The only way to reduce or eliminate OAS symptoms is to avoid the offending food(s). However, if reactions are mild, it may help to cook the food as this helps break down the proteins. Cooking doesn’t work for all foods, so looking for canned, pasteurized, processed or frozen foods may also be helpful. Lastly, try peeling the fruit and vegetables; most of the proteins in question will be found at or near the skin. These methods may help reduce symptoms, but likely won’t make them go away completely.
Here is a list of fruits and vegetables containing proteins that are generally cross-reactive with various pollens. Please note that you may react to some, but not all, of these items.
Foods related to birch pollen allergy:
- Almonds
- Apples
- Apricots
- Carrots
- Coriander
- Celery
- Cherries
- Fennel
- Hazelnuts
- Kiwi
- Nectarines
- Parsnips
- Peaches
- Pears
- Peppers
- Plums
Foods related to grass pollen allergy:
- Celery
- Cantaloupe
- Honeydew
- Oranges
- Peaches
- Tomatoes
- Watermelon
Foods related to ragweed pollen allergy:
- Bananas
- Cantaloupe
- Chamomile
- Cucumber
- Honeydew
- Watermelon
- Sunflower seeds
- Zucchini
This article was contributed by Jessica Riggs, MS, RDN, registered dietitian nutritionist with The Little Clinic (inside select Kroger locations). For more information about dietitian services, visit www.thelittleclinic.com/dietitians.
