Introduction:
Many individuals are commonly allergic to some foods. However, due to the global availability and increased consumption of exotic foods such as nuts, fruits, and vegetables, the incidence of oral allergy syndrome is on the rise. Oral allergy syndrome has oral reactions as well as extra-oral symptoms.
What Is Oral Allergy Syndrome?
Oral allergy syndrome (OAS) is the allergic reaction that is experienced by the affected person after consumption of foods like fruits, nuts, or even vegetables. The allergic manifestations are particularly seen in the oral cavity. This condition can also be triggered due to either pollen proteins or certain specific proteins that are present in most fruits and vegetables. In OAS, the immune system will try to produce antibodies that are in turn directed against the pollen or fruit or vegetable proteins. Researchers suggest that because pollen protein is structurally similar to the proteins found in some foods, allergic symptoms would be of acute onset soon after consuming these substances. However, the symptoms are limited only to the oral cavity.
What Is the History and Prevalence of Oral Allergy Syndrome?
The first description of OAS was given by Tuft and Blumstein in the year 1942 with their research linking this syndrome to be a sort of clinical hypersensitivity reaction caused by consuming fruits and vegetables that had cross-reactivity to birch pollen (birch pollinosis). In 1987 Amlot et al. first described the term oral allergy syndrome because the clinical symptoms were only present in the oral cavity.
Patients may exhibit a number of symptoms of OAS starting very quickly after consuming the trigger food. Prevalence is known to be higher in females than in males. Initially, they are manifested in the mouth or the oral mucosa as an itching and burning sensation and would also occur on the lips, mouth, ear, or throat. Perioral (around the mouth) inflammation or erythema (skin redness) is extremely common and generalized urticaria (erythematous swelling of the skin) can be seen. In severe cases, The patients may complain of severe swelling of the lips, tongue, uvula, or face. Difficulty in breathing or a sense of suffocation may be seen in some rare cases of OAS due to anaphylaxis (a type of allergic reaction) reactions.
According to medical research and statistical data, OAS in adults is one of the most common allergic reactions globally. This is caused or related to the consumption of specific foods. OAS also is attributed to more than 60 percent of these food allergies.
How to Manage Diet With Pollen Allergies and Imported Fruits or Veggies?
Many fruits and vegetables are imported from one country to another across the globe. With the advent of nutrition science and the increasing popularity of consuming different varieties of exotic fruits and vegetables in the diet, individuals who are possibly allergic to pollen protein or vegetable or fruit proteins would possibly report an increasing number of pollen-allergic symptoms after consuming such foods. If the affected patients of OAS exhibit specific allergic reactions to any food they consume, this calls for a discussion with the registered dietician, nutritionist, or allergist to chart down food in the options and dietary preferences. This helps to identify what would be suitable for optimal nutrition through diet.
What Are the Types of Allergic Reactions Seen in Oral Allergy Syndrome?
OAS is primarily a condition that is classified under the allergy type I or type II allergic reaction. These allergic reactions are primarily mediated by immunoglobulin E (IgE). In susceptible patients affected by OAS, the immune system would thus produce IgE antibodies against the pollen proteins causing oral allergic symptoms. Pollen allergies are also caused because of repeated exposure of an individual to the pollen present in some plants. Exposure to pollen happens during pollination by the air. This causes inhalation of the pollen and its exposure to the surface of the alveoli of the lungs (pulmonary alveoli). IgE-mediated food allergy is further classified into classes 1 and 2.
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Primary (Class 1) IgE Food Allergy: This starts manifesting in early life itself in childhood and represents the preliminary manifestation of this syndrome. The most common foods that the child would be allergic to, causing such symptoms are cow's milk, eggs, beans, or legumes such as peanuts, soybean fish, shellfish, and wheat. In this class 1 allergy, children below seven to eight years of age are mainly affected. The allergic reactions would not only occur in the gastrointestinal tract but also cause further symptoms like pulmonary (lung) obstruction or difficulty in breathing, urticaria, and atopic dermatitis (dry and itchy skin). Most children however are known to naturally outgrow this class 1 food allergy without any treatment as such within the first three to six years of life.
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Secondary (Class 2) Food Allergy: This type of allergic reaction is experienced by young adolescents and adult individuals. Common examples of this class 2 allergy are allergies caused by substances like pollen of birch, mug wort, and ragweed. This form of food allergy may be attributed to a result of immunological cross-reactivity occurring between the respiratory allergens and structural proteins present in the foods.
What Are the Methods of Diagnosis and Management of Oral Allergy Syndrome?
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Diagnosis:
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Prick-plus-prick testing is the main diagnostic test for preventing such allergic reactions. In this method, the fruit is pricked first and then the skin is pricked with fresh fruit extracts. This test can be sensitive in detecting allergen-specific IgE antibodies.
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In case the history of the patient to OAS is positive, but the prick test is negative, then a new provocation test with fresh food is conducted to specifically detect which foods the patient is allergic to.
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The oral provocation test is one of the safest diagnostic tests for confirming the presence of the disease.
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Management:
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Nutrition experts also recommend cooking and canned foods to raw or fresh foods because many of the immunogenic proteins one finds in fresh fruits or vegetables are unstable to heat and may disintegrate preventing potential allergies.
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The Patients should be made aware of their syndrome and their families or caregivers should also be instructed to read the product labels before purchasing foods or cooking products. So that the relevant food allergens can be avoided easily. Important pharmacotherapy modalities can be used in severe cases. This involves the use of antihistamine drugs such as oral antihistamine agents like Cetirizine 10 milligrams or by the intramuscular aqueous solution of Epinephrine at the dose of 0.01 milliliter per kilogram (1 : 1000 dilution).
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Conclusion:
In stark contrast to other allergic conditions or reactions that are seen in the body, OAS is an allergic reaction specifically limited only to the oral mucosal membranes. The lips, the tongue, or the throat are commonly involved portion. There is no standard treatment for mild cases except for avoiding allergy-causative food. OAS should be mainly managed according to the clinical features of affected patients. In some cases, it may require multidisciplinary management by the physician, dentist, dermatologist, or otolaryngologist.
