Clustering of Food Causing Oral Allergy Syndrome in Patients with Birch Pollen Allergy

Abstract

Background: Birch pollen allergic patients often report oral and pharyngeal hypersensitivity to fruits and vegetables such as apples and peaches because of cross-reactivity. This phenomenon, called "oral allergy syndrome" (OAS), is sometimes accompanied by a systemic reaction and is considered to be an IgE-mediated allergy. We evaluated reciprocal relationships between food causing OAS using patient's reports and classified food in patients with birch pollen allergy. Methods: We interviewed 272 patients who had episodes of OAS and had IgE to birch pollen. Their mean age of the 198 women and 74 men was 34 years (15 to 65). We evaluated the reciprocal relationships between 14 foods frequently causing OAS—apples, peaches, cherries, kiwi, pears, melons, plums, strawberries, persimmons, tomatoes, grapes, watermelons, mangos, and bananas—classifying them by cluster analysis and kappa statistics. Results: The 14 foods were classified into rose-family and non-rose family. Rose-family fruits—apples, peaches, cherries, pears, plums, and strawberries—made a large cluster and were associated reciprocally. Melon and watermelon were associated. Melon and kiwi were not associated with rose-family fruits. Non-rose family foods—kiwi, melons, persimmons, tomatoes, grapes, watermelons, mangos, and bananas—made a large cluster and were partly associated. Conclusions: Foodstuffs causing OAS were classified into two groups based on patient's reports. Some clusters of foodstuffs were related.