Oral allergy syndrome, allergic response from fruit

For some of the nation's 35.9 million hay fever sufferers enjoying one of summer's fresh peaches or a juicy tomato may cause additional discomfort.

A few bites of raw fruit or vegetable could result in itching or swelling of the lips, inner ears, tongue, throat or roof of the mouth. Known as Oral Allergy Syndrome (OAS), the reaction is caused by an allergic response initially directed to the pollen that crosses over to similar proteins in the foods.

Individuals with hay fever to certain tree (birch, alder or hazel) grass or weed (such as ragweed or mugwort) pollens may experience symptoms of an allergic reaction after eating certain raw vegetables or fresh fruits. The 'oral' nature of the symptoms presumably is due to the fact that these proteins are digested by stomach juices and do not enter the bloodstream. It is unusual for these symptoms to go beyond the mouth.

Because the allergens responsible for these reactions are usually destroyed by heating or digestion, affected individuals can usually eat fruits or vegetables that have been cooked, baked, or canned. For example, a person may experience itching of the mouth and tongue after eating a fresh apple, but may be able to eat apple sauce or an apple pie without trouble.

"If itchy mouth is the only symptom, avoidance of raw fruits or vegetables and eating only cooked versions is sufficient. However, if symptoms are caused by cooked fruits/vegetables or go beyond mouth and involve generalized hives, vomiting, or difficulty breathing, the patient should consult an allergist because these may signal a more severe allergy. In such case testing and more extensive avoidance may be necessary," said Anna Nowak-Wegrzyn, M.D., an Assistant Professor of Pediatrics, Pediatric Allergy and Immunology, at the Mount Sinai School of Medicine in New York City.

The Food Allergy & Anaphylaxis Network (FAAN) recommends that with all forms of food allergy, identification of the responsible food and avoidance of that food is the key to successful long-term management. Individuals should consult a physician with specific questions.

"These are potential associations. Not every patient allergic to pollen develops symptoms with cross-reacting fruits or vegetables. Patients may react to a few but not all fruits and vegetables," said Anne Munoz-Furlong, President & CEO of FAAN. "Also, there is some confusion regarding the terminology. Some experts propose to replace the term OAS with a new name, pollen-plant food allergy, to better describe reactions to fruits and vegetables cross-reactive with pollens. Both may be referred to when consulting with a physician."