If you experience itchiness or hives in your mouth area after eating raw fruit or vegetables and you have seasonal allergies you may be suffering from oral allergy syndrome. According to Dr Robert Wood, chief of pediatric allergy and immunology at Johns Hopkins Children's Center, the proteins in some fruits and vegetables are similar, although not identical to proteins in some pollens can be similar enough to confuse some immune systems.

Cooking the offending fruits and vegetables can ‘denature’ or change the shapes of these proteins, so many people with oral allergy syndrome will usually be able to eat the cooked fruit or vegetable without a problem; for others the peel of a fruit has more allergens than the meat, so peeling it also helps.

Because the reaction is usually localised to the mouth area, including lips, tongue, and throat, some people will choose to ignore the symptoms or use over the counter antihistamines to alleviate the symptoms and continue to eat offending foods. However, in rare cases oral allergy syndrome can cause more dramatic, even anaphylactic, reactions.

While other kinds of food allergies usually appear in the first two or three years of life, pollen allergies that relate to oral allergy syndrome develop more slowly often not appearing until teenage and young adult years. A person who moves to a new part of the country, having never been exposed to the native pollens there, may become allergic to those pollens and have some spill-over into food allergies. Typically, according to Dr Wood, once people start to react to some foods, they will also react to other foods in the same group. People may find that their allergies to raw fruits and vegetables subside during the season when the associated pollen levels are low. For example, a person may react to raw apples from March to October, but feel fine when eating them from November to February, when birch pollen is low.

Pollens and associated foods
Ragweed:
Bananas, melons (watermelon, cantaloupe, honeydew), tomatoes

Birch: Apples, carrots, celery, peaches, pears, potatoes, hazelnuts

Grass: Kiwis, tomatoes

Mugwort: Apples, carrots, celery, kiwi fruit, peanuts, some spices (caraway seeds, parsley, coriander, anise seeds, fennel seeds)

Source: The Mayo Clinic

Read more

First published in June 2009

Click here for more research reports

Top of page