Duke Medicine: Foiling food allergies

A growing number of families are making adjustments because of food allergies.

Studies show that eleven million Americans have food allergies and one-and-a-half million have a peanut allergy. According to the Food Allergy and Anaphylaxis Network, from 1997 to 2002 the incidence of peanut allergy in children had doubled.

Duke’s Wesley Burks, MD, chief of pediatric allergy and immunology, says that food allergies typically appear between six and 18 months of age, since that is when many youngsters first sample foods such as peanut butter.

While children often outgrow certain food allergies, such as to eggs and milk, peanut allergies are usually for life.

Not every reaction to a food is an allergy. A detailed clinical history is needed to differentiate viral gastroenteritis or food poisoning from food allergies.

“You need to find out the timing of the ingestion and the clinical symptoms,” Burks says. “Reactions to an allergen such as peanuts occur literally within minutes, not more than an hour or two, after ingestion. Food allergy symptoms are also isolated to the GI tract, the respiratory tract, and the skin.”

These symptoms include abdominal cramps, vomiting, diarrhea, skin symptoms like hives or itchy rash, difficulty breathing, and swelling of the lips or the eyes.

Also, “food-allergy symptoms are reproducible,” Burks says. “Each time they have the food, they ought to have fairly similar symptoms.”

Taking a good clinical history means tuning in to the patient. “The thing I like as a parent is that Dr. Burks will talk with the kids himself,” says Theresa Nguyen, the mom of three children with food allergies. “I’m sitting there, but his conversation is with the kids, asking them for their contribution in terms of what’s bothering them or what they want help with.”

Diagnosis also depends on tests to measure the blood level of the immune protein IgE that triggers allergic reactions, and skin tests for sensitivity.