True allergy implies that the allergic reaction involves a part of the immune system called Immunoglobulin E (Ig E). IgE is the antibody that induces or mediates the food related symptoms. There are other food related syndromes, some of which involve physiologic symptoms and some of which are based on other aspects of the immune system. However, only a true food allergy involves the IgE mechanism.
An example of a physiologic food problem would be the adverse reaction some people have to milk sugar (lactose). Some people cannot metabolize lactose properly due to a deficiency in the production of the enzyme lactase. The sugar therefore sits in the bowel and eventually causes cramps and diarrhea. This form of food related adverse reaction is called a food sensitivity or intolerance.
An example of a food related syndrome that is immunologically mediated, but is not an allergy, could be Celiac disease. In this problem antibodies made from immunoglobulin IgA or IgG against the protein gluten cause gastrointestinal symptoms. Although involving the immune system, this syndrome does not involve IgE and is not a true food allergy.
True allergy, involving IgE, can be systemic or local in nature and presentation. An example of a systemic allergic reaction would be the multiple symptoms that are involved with a severe peanut allergy or perhaps in a bee sting allergy. Systems of the body involved could be respiratory, skin, gastrointestinal, and cardiovascular. Symptoms might include wheezing, hives, cramps, and low blood pressure. These reactions can be fatal.
In Oral Allergy Syndrome, the symptoms are local and typically include itching and tingling of the mouth, throat, and lips. The mouth and throat have a contact induced bumpiness. These symptoms occur with eating raw fruit, raw vegetables, raw spices, and uncooked nuts. Roasted nuts can also induce the symptoms.
Oral allergy syndrome only occurs in people who have allergies to pollens. Protein allergens in the raw fruits, vegetables and nuts are similar to and shared by the allergens in the pollens. Your immune system, essentially, acts as if you are eating the pollen.
Stomach acid will destroy the raw food allergens so the symptoms usually stop when you swallow the food. The allergy rarely progresses to a systemic reaction. Cooking the food will also destroy the allergen protein so canned and cooked fruits or vegetables rarely cause symptoms. So while raw apples often are associated with oral allergy syndrome, apple pie and applesauce almost never cause symptoms.
Unfortunately, about 5% to 10% of the time oral allergy syndrome symptoms are more complex and could involve more severe symptoms. Peeling and itching of the hands when raw foods are touched can occur. Stomach cramps when raw foods are ingested has occurred. And there are rare reports of progression to actual systemic allergic reactions with throat tightness, wheezing, vomiting, or changes in blood pressure. These types of symptoms will require in depth evaluation by an allergist and perhaps the need to carry epinephrine with you.
The foods and pollens involved in Oral Allergy Syndrome typically fall into several groups as seen in Chart 1:
|Birch pollen||Apple, carrot, cherry, pear, peach, plum apricot, nectarine, kiwi fruit, honey, tomato, peas, potato, spinach, green pepper, lentils, beans, peanut, parsley, anise, dill, fennel, caraway, coriander, cumin, wheat, buckwheat, hazelnut, walnut, almond.|
|Mugwort or Sage Pollen||Celery, carrot, spices, melon, watermelon, apple, chamomile, hazelnut, anise, fennel, coriander, cumin|
|Grass Pollen||Potato, melon, tomato, watermelon, orange, cherry, peanut, kiwi.|
|Ragweed Pollen||Watermelon, cantaloupe, honeydew, chamomile, honey, banana, sunflower seed, zucchini, cucumber|
|Latex||Avocado, potato, banana, tomato, chestnut, kiwi fruit, herbs, carrot.|
The diagnosis of Oral Allergy Syndrome can often be made from history alone. At other times your trusted Allergy Partners allergist will do more in depth studies such as skin tests or blood tests for specific IgE to pollens and fruits or vegetables. On occasion, oral challenges are conducted under closely observed conditions in an allergy office. These challenges should only be performed under the supervision of your Allergy Partners allergist.
The treatment of Oral Allergy Syndrome involves avoidance of the raw form of the foods involved. This would include the dried or dehydrated forms of the foods. The cooked or baked forms of the foods should be able to be tolerated. Sometimes, simply peeling the involved food (especially with apples) may be all that is necessary. If any systemic symptoms have occurred, then the total avoidance of that food is required. An in depth evaluation by your Allergy Partners allergist would follow, and the patient should be provided with and taught the proper use of epinephrine.
Oral Allergy Syndrome is very common in pollen allergic people. An understanding of it and knowledge on how to evaluate its symptoms will be very helpful in alleviating food related anxiety in people with all types of allergy.
To learn more visit your trusted Allergy Partners physician or visit allergypartners.com
Dr. Michael Neuland
Allergy Partners of the Emerald Coast