ORAL ALLERGY SYNDROME

Definition : Occurs in individuals who have a major allergy to an inhaled allergen (usually a pollen). Certain foods have a similar molecular structure as certain components of the pollen. There can be cross-reactivity between the pollen and the food. In basic terms, when you eat one of these cross-reactive foods your body thinks you are eating the inhaled allergen (pollen) that you are allergic to. Every person is different and has their own specific foods that cause their symptoms.

Typical Reaction : numbness and/or tingling and/or itching of areas around the mouth (lips, mouth, tongue, throat, face), +/- swelling of these same areas.

The reaction usually starts within seconds to minutes of eating the particular food. Occasionally the nose or eyes can be involved, and if an individual eats a significant amount abdominal pain/bloating can occur. Rarely the reaction can be more generalized and involve the chest, skin, or bowel (cramps,bloating,vomiting,diarrhea).

CAUTION : THIS SYNDROME CAN BE CONFUSED WITH ANAPHYLAXIS (a life threatening allergic reaction) AND CAN ONLY BE DIAGNOSED BY AN ALLERGIST WITH APPROPRIATE SKIN TESTS.

COMMON SYNDROMES

BIRCH pollen allergy : can be associated with the following foods; apples, cherries, peach, pear, nectarine, plum, apricot, hazelnut, walnut, almond, pecan, brazil nut (i.e. tree nuts), kiwi, carrot, celery, potato, tomato, coconut, turnip, parsnip. (sometimes peanut or soy)

RAGWEED pollen allergy : cantaloupe, watermelon, honeydew melon, cucumber, zucchini, banana.

MUGWORT pollen allergy : celery, carrot, caraway, dill, parsley, fennel, green pepper, aniseed, (?melons).

GRASS pollen allergy : potato, tomato, melon, peanut, orange, celery, kiwi, buckwheat, and can cross-react with some foods above also.

LATEX (natural rubber) allergy : banana, avocado, chestnut, papaya/papain, (possibly potato, tomato, mustard, kiwi)

TREATMENT

The basic treatment is to avoid the specific foods that cause your symptoms.

The typical oral / facial symptoms can usually be helped with an oral antihistamine (ReactineTM, ClaritinTM, AllegraTM, BenadrylTM, ChlortripolonTM) taken immediately at the onset of symptoms. Note: antihistamines are more effective if taken prior to a reaction. For the rare individuals with generalized/severe reactions an EpiPen TM or Allerject TM may be required.

Oral Allergy Syndrome is often associated with seasonal allergic rhinitis (nasal&eye allergy, hayfever) and can eventually result in the development of asthma. Allergy shots (immunotherapy) are usually recommended for individuals who: have multiple foods that cause symptoms, have major associated seasonal allergies (or whose hayfever is clearly getting worse), have associated or developing asthma. Allergy shots radically decrease seasonal allergy symptoms, gradually improve the oral allergy symptoms (so that some of these foods can eventually be eaten again), and can improve or prevent the development of asthma.

FOOTNOTES

There are a few individuals who have the typical food reactions to the foods above, but who do not have any significant positive skin tests to pollen and have no history of seasonal allergies. These individuals tend to have more severe reactions to the foods listed above and often require strict avoidance measures and an EpiPen TM or Allerject TM (epinephrine autoinjectors) . I call this "reverse OAS" - where you become allergic to the foods first. I am not sure these individuals ever become pollen allergic.

OAS has been called many other names; pollen food syndrome, pollinosis food syndrome, etc.

The geographic area I practice in has a large amount of springtime birch pollen (which cross-reacts with tag alder, hazel, &oak pollens). Most of my OAS patients fall in the birch group. I likely have one of the largest groups of patients ever treated with immunotherapy for this problem.

There are actually several groups of molecules (usually proteins) in food that can cross-react with pollen components. One particular group of proteins, called profilins, are distributed widely throughout most of the plant kingdom and account for some of the cross-reactivity. Another group of cross-reactive proteins belongs to the plant defense systems. These plant defense proteins are produced by the plant and incorporated into the plant/fruit when the plant is under stress. Stress could include the plant having a poor growing season due to climate problems, or the plant could have been attacked by insects, viruses, bacteria, fungi, etc. The greater the stress the plant experienced the greater will be the production of defense proteins. This explains one of the interesting phenomenon that occurs with oral allergy syndrome. When oral allergy syndrome is just beginning many patients find that it will be only the occasional piece of fruit or vegetable that will cause typical symptoms while eating the same fruit or vegetable at other times will cause no symptoms whatsoever. Patients often attribute this to chemicals or pesticides in the fruit or vegetable. You can now appreciate that it depends upon the specific growing season and stress the plant had that determines how allergenic it or its fruit will be. You also have to take into account that some plants and their fruits inherently have more profilin, defense proteins, etc. (example: Granny Smith apples have a much higher content of cross-reactive proteins than other apples and thus will cause more significant oral symptoms, and each specific brand of apple tends to have a certain inherent amount of these cross-reactive of proteins, so each brand will tend to be more or less allergenic; keeping in mind that the specific growing season always affects the end result). Most of these cross-reactive proteins are heat labile (broken apart when heated). This explains why it is the fresh/raw fruit-vegetable that causes oral allergy symptoms, but when they are cooked/heated/canned they do not. A fresh apple causes symptoms but apple pie/apple sauce does not. In the case of tree nuts, heating/roasting tends to make them only less allergenic but does not completely eliminate the oral symptoms. One of markers that oral allergy syndrome is becoming severe is when cooking does not eliminate symptoms anymore.

Bruce Sweet M.D., 2015