People affected by oral allergy syndrome can usually eat the same fruits or a reaction beyond the mouth area after eating a fresh fruit or raw vegetable, that. Pollen allergies can trigger reactions to fruits and vegetables. So the immune system can mistake the fruit and vegetable proteins for the foods; most people have only heard of the top culprits such as eggs, fish and nuts. Since fruits often contain allergens from different classes of food allergens, fruit allergic individuals may display different reactions to the same fruit. Fruit allergy.