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Why An Allergy to Fruit, But Not Fruit Juice?

Prince George's County Dr. Naba Sharif answers questions about allergies from Patch readers. This week she helps one reader understand why people can be allergic to a fruit but not its juice.

 

Reader Question: Can someone be allergic to fruit but not the same fruit juice? My husband develops an itchy throat and hoarse voice when he eats apples, but he has no reaction when he drinks apple juice. 

 - Sarah M., Silver Spring, MD

 

Dr. Naba Sharif: The simple answer to your question is, yes – and it is not that uncommon! In fact, 60 to 70 percent of people with pollen allergy can have oral allergy syndrome (OAS), which results from cross-reactivity between the proteins in pollen and those found in raw fruits, vegetables, and some seeds, spices and nuts. Basically, your body confuses the proteins between the two, resulting in symptoms of an allergy. If you’re allergic to birch tree, for example, then apples, peaches and hazelnut, among other foods, can trigger OAS. 

Due to the fact that pollen allergy is at the root of it, OAS can be more severe during the season of your particular pollen allergy. The allergic reactions usually occur only when the food is raw.  For the vast majority of people affected, symptoms are limited to itching or tingling of the lips, tongue or throat, or transient, mild swelling – symptoms which improve with over-the-counter antihistamines.  For some people, peeling or touching the problematic foods without gloves may cause a itching or a rash where the food touches the skin.  However, one to two percent of people with OAS may experience anaphylaxis, which can be life-threatening.    

For this reason, avoidance of the irritating foods is the safest way to prevent severe symptoms, and some Allergists even prescribe epinephrine injectors as a cautious measure.  However, because the more allergic protein in fruits may be in the skin (eg. in apples, peaches etc.), some people with OAS related to these fruits can eat them if the skin is peeled away. Similarly, heat can denature the cross-reacting proteins so they no longer look like those in the associated pollen – and therefore, cooked, processed, pasteurized, canned or baked foods containing the food may be tolerated without a problem. This is the reason that your husband, for example, would have symptoms with raw apples, but likely not to apple juice, apple sauce or good old apple pie. The exceptions to this, however, are nuts and celery, which may cause allergic reactions whether raw or cooked.  

OAS is not due to pesticides, chemicals or wax on the fruit – those these are also things one can be allergic to and should be noted as possibilities if, for example, you can tolerate the same organic food but not the inorganic version.  

As with all allergies, a careful history by an Allergist is important to determine the triggering foods and timing and nature of any subsequent reactions.  In diagnosing OAS, skin testing using commercial allergy extracts are readily available, but may sometimes be negative unless the actual fresh fruit is used for the prick test.  If there is no associated pollen allergy and the commercial testing to the food is positive, this may indicate a true allergy to the actual food instead of OAS – and an increased risk of a severe reaction. 

OAS is usually a life-long condition, though if the pollen allergies improve, symptoms of OAS may sometimes improve as well.  Therefore, with severe symptoms, allergy shots (desensitization) to the pollen may also actually help OAS. 

Hope that helps and good luck!

-Dr. Sharif

AmazingAllergist.com July 18, 2012 at 10:04 AM
Dr. Sharif, this is a great and very informative article. Keep it up. It's making a difference in the lives of allergic individuals. We invite you to join www.AmazingAllergist.com blog team!- Dr. Shah
Naba Sharif, M.D. July 19, 2012 at 03:51 AM
Thanks for the positive feedback Dr. Shah; I truly believe in educating the community and empowering patients to learn more about their allergic conditions. You should feel free to cross-reference my column on your blog if you'd like!

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