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The question: Apples and peaches make my mouth itchy. What other foods should I avoid?

The answer: You may have oral allergy syndrome, an allergic reaction to proteins in certain fruits, vegetables and nuts. Symptoms include itchy mouth, scratchy throat or swelling of the lips, mouth, tongue and throat.

Oral allergy syndrome mainly affects people with birch pollen allergies, but people who are allergic to grass and ragweed may also be affected. The reaction occurs because proteins found in some fruits, vegetables and tree nuts are very similar to those found in pollen. The immune system gets confused and triggers an allergic response when you eat, for example, an apple or a peach.

If you have a birch pollen allergy, you may react to apple, apricot, cherry, kiwi, nectarine, peach, pear, plum, prune, beans, caraway, carrots, celery, coriander, cumin, dill, fennel, green pepper, lentils, parsley, parsnip, peanut, peas, potato and tomato. Almonds, hazelnuts, walnuts and sunflower seeds may also cross-react with pollen.

Foods to watch out for if you have ragweed allergy include banana, cantaloupe, honeydew, watermelon, cucumber and zucchini. Kiwi, melon, orange, tomato, and watermelon may trigger symptoms in people with grass allergy.

Avoiding trigger foods is the best way to avoid symptoms. However, many people find that eating the food after it's cooked – applesauce, canned peaches, etc. – does not provoke symptoms. Cooking changes the structure of proteins so they no longer resemble those in pollen or grass. Peeling fruit may also help since most of the offending proteins are in the skin.

I recommend you consult an allergist to determine if an allergy is causing your symptoms. Most cases of oral allergy syndrome are mild, however research suggests that about 2 per cent of people with the condition can progress to having a serious allergic reaction called anaphylaxis.

Leslie Beck, a registered dietitian, is the national director of nutrition at BodyScience Medical. She can be seen every Thursday at noon on CTV News Channel's Direct ( ).

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