ORAL ALLERGY SYNDROME

What is an “Oral Allergy Syndrome”?

Oral allergy syndrome is an allergic (immunologic) reaction to certain proteins in a variety of fruits, vegetables and nuts, which develops in some people with pollen allergies. It is referred to as an oral allergy syndrome because it usually affects the mouth and throat.

These reactions are not related to pesticides or metals.

Who is affected and what pollens are involved ?

Oral allergy syndrome is nearly always preceded by hay fever and tends to occur most often in older children and adults. It is usually associated with birch-pollen allergies but it can also affect people with allergies to the pollens of grass, ragweed (more common in North America) and mugwort (more common in Europe). These reactions can occur at any time of year, but are often worse during the pollen season involved.

What are the symptoms and when do they occur ?

Symptoms may include itching and burning of the lips, mouth and throat, watery itchy eyes, runny nose and sneezing. Some individuals report that peeling or touching the offending foods may result in a rash, itching or swelling where the juice touches the skin. More serious reactions can include hives and swelling of the mouth, pharynx and windpipe. In rare cases, severe allergic reactions have been reported such as vomiting and diarrhea, bronchial asthma, generalized hives and anaphylactic shock. Symptoms usually develop within minutes of consuming or touching the food, but occasionally occur more than an hour later.

Are all reactions to fruits and vegetables associated with "Oral Allergy Syndrome" ?

No. A variety of fruits, vegetables and their juices, including orange, tomato, apple and grape, sometimes cause skin rashes and diarrhea, especially in young children. Strawberries occasionally cause hives

What foods are involved ?

Foods associated with birch, ragweed, grass and mugwort pollen are listed in the following table. Most reactions are caused by raw foods, since allergenic proteins are usually destroyed by cooking (i.e., heat labile). The main exceptions to this are celery and nuts which may cause reactions even after being cooked. Some plant parts, such as the skin, may be more allergenic than others, however the allergic characteristics of some fruits seems to decrease during storage. Foods associated with the oral allergy syndrome which have occasionally been reported to cause anaphylactic reactions include: kiwi, hazelnut, white potato, celery, parsley, beans, and cumin..

FOODS MOST COMMONLY ASSOCIATED WITH
BIRCH, RAGWEED, GRASS AND MUGWORT POLLENS

Allergies to this type of Pollen	May also trigger an allergic reaction to these foods
Birch	Fruits kiwi, apple, pear, plum, prune, peach, nectarine, apricot, cherry Vegetables celery, carrot, parsnips, parsley, dill, anise, cumin, coriander, caraway, fennel, potato, tomato, green pepper, lentils, peas, beans, peanut Nuts hazelnut, walnut, almond Seeds sunflower
Ragweed	Fruits banana, watermelon, cantaloupe, honeydew Vegetables zucchini, cucumber
Grass	Fruits melon, watermelon, tomato, orange, kiwi
Mugwort	Fruits apple, watermelon, melon Vegetables celery, carrot

What can sensitive individuals do to avoid a reaction?

Individuals who are hypersensitive to the foods identified in the above table usually find that they can consume these foods if they are well cooked, canned or micro waved. People who develop a rash, itching or swelling when touching or peeling these foods may prevent this by wearing gloves.

Consultation with a qualified allergist is recommended to determine the cause of reactions to plant foods, and whether any special precautions are advisable.

Reference :

Zarkadas M, F.M. Scott, J. Salminen, A. Ham Pong. Common Allergenic Foods and Their Labelling in Canada - A Review. Canadian Journal of Allergy and Clinical Immunology, 1999;4:118-141.

P0154E-00
January 2000