There is a condition called ORAL ALLERGY SYNDROME.  This is because of cross reactivity between pollen allergens and food allergens in fresh fruits and vegetables. Common pollen allergens are found in tress (such as Birch), Ragweed and some grasses. These pollen allergens cross react with food allergens such as Profilins and PR-!0 group of  food allergens.  

Generally the symptoms are limited to the oral cavity in the form of itchy lips, tongue and throat, giving it the name of Oral Allergy Syndrome.   In a small percentage of patients symptoms could be more severe and may include nausea, vomiting, diarrhea, generalized itching and skin rashes and in rare instances anaphylaxis and shock. 

These food allergens are heat sensitive, therefore most patients can eat these fruits if they have been cooked or processed.  For example one may not be able to eat fresh apples and peaches but pie made from apple or peach is well tolerated.  These allergens are also digested easily by the  stomach therefore they do not survive in the GI tract  for systemic absorption. 

Treatment involves,  avoiding these foods.  Since some of these may progress to more serious  systemic symptoms, one should seek help from an allergist.  It would be prudent to obtain an epinephrine autoinjector such as Epi Pen or Adrenaquick to have on hand in case of a serious life threatening reaction.  Testing with conventional skin testing extracts may not be helpful because these allergens get destroyed during the manufacturing process.  Testing done utilizing extracts made from   fresh fruit may be more diagnostic. Patients will also  show reactions on skin tests for pollens from trees, grasses and ragweed etc. Since majority of these patients have typical hay fever allergies, desensitization shots for these offending pollens has been shown to  reduce the sensitivity to these foods.  Therefore allergy shots in such patients will help with hay fever and such food intolerances as well.