What is oral allergy syndrome?

Oral allergy syndrome is a complication of hay fever, and is a type of food allergy, particularly to fruits, nuts, and vegetables. You might notice an itching or burning sensation in the lips, mouth, or throat. Swelling of the throat may lead to difficulty in breathing. If the allergen in the food passes into your gut, symptoms might include diarrhoea, vomiting, or abdominal cramps. It happens because some allergens in food may be structurally and chemically very similar to the allergens in pollen, and your immune system reacts with them as well. In addition, some of these foods can be coated in pollen.

Different plants can cause cross-reactivity with different foods:

• Alder tree pollen can cross react with almonds, apples, celery, cherries, peaches, hazelnuts, pears, or parsley.
• Birch tree pollen can cross-react with almonds, apples, apricots, bananas, carrots, celery, cherries, coriander, figs, hazelnuts, kiwifruits, nectarines, pears, peaches, plums, parsley, potatoes, strawberries, or wheat, as well as a few other foods.
• Grass pollen tends to cross react with figs, melons, tomatoes, and oranges.
• Ragweed pollen can cross-react with watermelon, honeydew, bananas, and a few other foods too.
• Mugwort pollen can cross-react with carrots, celery, coriander, or peppers, as well as some other foods.

With some of these foods (such as apples), cooking them can destroy the 3-dimensional shape of the proteins causing the allergy. If your immune system is reacting against a chain of amino acids (the building blocks of proteins) rather than an active site (epitope) on a protein with a specific 3-dimensional shape, this cannot be done. In addition, some proteins, like lipid transfer proteins (found in most cells) are very heat resistant. Foods such as strawberries or celery cannot be treated this way, and if you have an allergic reaction on eating them, it is best to avoid them altogether.

Allergies Treatment Guide Index:

• What is hayfever?
• What are the signs and symptoms of hay fever?
• Can hay fever cause major problems in a person's life?
• How is hay fever diagnosed?
• How is hay fever managed?

• Is there a cure for hay fever?
• How can I live with hay fever?
• What is oral allergy syndrome?
• What is perennial allergic rhinitis?