Oral Allergy Syndrome, often shortened to OAS, is a type of food allergy that is linked to seasonal pollen allergies. It happens because certain raw fruits, vegetables, and nuts contain proteins that are similar to pollen proteins.
When someone with pollen allergies eats one of these foods, their immune system can react. The symptoms are usually mild and limited to the mouth and throat. This can include itching, tingling, or slight swelling of the lips, tongue, or throat right after eating the food.
Common trigger foods include raw apples, carrots, celery, peaches, cherries, and some nuts. The specific foods often depend on which pollens someone is allergic to. For example, people with birch pollen allergies may react to apples or carrots.
One interesting thing about Oral Allergy Syndrome is that cooking the food often prevents the reaction. Heat changes the protein structure, so baked apples may be fine even if raw apples cause itching.
Even though symptoms are usually mild, it is still important to discuss them with a board certified allergist. In rare cases, reactions can become more serious.
