Summertime fruit, vegetables allergies

by Christopher C. Chang, M.D., Ph.D.

We all look forward to enjoying summer's bounty of fresh fruits and vegetables at the peak of the season. However, for some of us, fruits and veggies can cause allergic reactions ranging from hives and swelling of the skin to irritation of the mouth and throat. Some of the most common fruit allergies include melons, apples, strawberries and bananas.

What parents can do: Once you know a child is allergic to these foods, avoidance is the only reliable treatment. But if you're not sure there has been a reaction, skin-prick test or a blood test may be helpful. After all, we want kids to enjoy these healthy foodsif they can indeed tolerate them.

Cross-reactivity clues: Interestingly, there is a high degree of cross-reactivity between certain botanical families. Groupings of foods are associated with various pollens. For example, those allergic to birch tree pollen aremore likely to also show sensitivity to apples, peaches, apricots, cherries, carrot, celery, soybeans, peanuts and some spices such as caraway and fennel. Those who are sensitive to ragweed may also show reactivity to melons, cucumber, and bananas. Children and adults with mugwort allergies may also react to bell peppers, garlic, onion, cauliflower and broccoli. Although there is less cross-reactivity seen with grass pollen, patients with those allergies may be sensitive to potatoes, tomatoes, melons and oranges.

Cautions: For most people with fruit and vegetable allergies, the typical reaction is known as oral allergy syndrome – itching and mildswelling of the lips, mouth and throat. If a child has shown clinical symptoms, especially swelling or itching in the throat, we have to take it very seriously. Swelling of the airways can impede breathing. Although fruit allergies tend not to cause the severity of reaction that peanuts and tree nuts do, we do want to be cautious because we don't know how far it might progress to becoming asystemic reaction.

How an allergist can help: Allergists will always take a careful history to determine if a pollen allergy is present.We need to know how the child has reacted to plant foodsand whether or not cooked forms of the foods are tolerated.We examine the patient to determine what the manifestations are. Are hives, wheezing or nasal congestion present? Based on those diagnostic questions and our physical examination, we may proceed with skin-prick testing and blood testing. But even then, the answer may not be definitive.

To be absolutely certain, we conduct a challenge test, where the patient is given the food and we observe the reaction over time in the clinical setting where rescue measures can be implemented if necessary. If the sensitivity is confirmed by testing, there is no safe amount or preparation of the food and the child should strictly avoid it. Long term studies on the persistence of pollen-food syndromes such as oral allergy syndrome are lacking, but it is believed that this type of allergy is usually life-long.  Whether or not allergy shots to the related pollen helps the food allergy is unknown. If patients experience systemic reactions, or if they have a positive skin-prick test and a positive history, they should carry an Epi-pen autoinjector at all times.

Do your children have fruit or vegetable allergies? How do you keep them safe?

Christopher C. Chang, M.D., Ph.D., is division chief of the division of pediatric allergy/immunology at Nemours/Alfred I. duPont Hospital for Children, and clinical professor of pediatrics at Jefferson Medical College.