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.