New guidelines reveal complexity of food allergy

April 2006

Allergists teamed together to developed evidence-based guidelines for food allergy diagnosis and management, which have become more sophisticated and challenging in recent years due to the increase in prevalence of certain food allergies.

“Designed to improve patient care, the guidelines provide practicing physicians with an evidence-based, broadly accepted approach to the diagnostic evaluation and management of immunoglobulin E (IgE)–mediated food reactions,” said chief editor Jean A. Chapman, MD, of Cape Girardeau, Mo.

“The practice parameter on food allergy represents more than 10 years of research and investigation of literature by members of the Joint Task Force,” added Chapman, American College of Allergy, Asthma and Immunology (ACAAI) emeritus fellow.

Although adverse food reactions have been reported in up to 25% of the U.S. population at some point in their lives, the prevalence of food allergy is much lower than the number of suspected food allergies. It varies between 2% in adults and 5% in children in most studies, and is higher in individuals with atopic dermatitis, certain pollen sensitivities or latex sensitivities.

“The guidelines reinforce the need for physicians to think about food allergy as the potential cause of a patient’s symptoms, whether it be gastrointestinal complaints or skin problems,” said John Oppenheimer, MD, of the University of Medicine and Dentistry of New Jersey. “Likewise, if a patient has a list of foods they think they are allergic to, it’s important to differentiate what’s truly an allergy and what isn’t. If a patient is trying to avoid 10 or 15 foods, it becomes really cumbersome, and if someone does have an allergy on that list, it is much more difficult to avoid the important allergen.”

Guidelines in sum

Food allergies are more common in children than in adults. According to the researchers, the most common food allergens in infants and young children are cow’s milk, hen’s egg, peanut, tree nuts (such as walnut, hazelnut, Brazil nut and pecan), soybeans and wheat. Although sensitivity to most allergens is lost in late childhood, allergy to peanut, tree nut and seafood is likely to continue throughout the patient’s life. About 20% of children with peanut allergy lose their sensitivity. The most common foods causing allergy in adults are peanuts, tree nuts, fish, crustaceans, mollusks, fruits and vegetables.

“The most important diagnostic tool is the patient’s history. Is there an association between eating the food and having symptoms?” said Jay M. Portnoy, MD, of the section of allergy, asthma and immunology at the Children’s Mercy Hospital and professor of pediatrics at the University of Missouri-Kansas City School of Medicine. “Hidden food allergy is uncommon. Most food allergies occur with a direct relationship – you eat the food, then you have a reaction. It is usually a pretty obvious reaction.”

Due to recent developments in laboratory technology, it has become common practice for physicians to order blood tests for 20 or 30 foods when testing for other allergies, even when there is no history of allergic food reactions, according to Oppenheimer.

“Being a good historian and culling down what foods you think are important should determine what types of tests are done,” he said.

A detailed discussion of skin prick or puncture tests, serologic tests for specific IgE and oral food challenges is provided in the practice parameter.

“Just because you have a positive test to a food doesn’t mean you are allergic to the food,” Portnoy said. “It is really important that the symptoms correspond to the test.”

The guidelines recommend carrying more than one epinephrine auto-injector because anaphylactic reactions may be prolonged, seeking immediate medical care after a reaction and monitoring patients for an appropriate period. Peanut and tree nuts, often with delayed administration of injectable epinephrine, cause most fatal and near-fatal food allergic reactions in the nation.

“The treatment for food allergy is to avoid the food. Inevitably, you’re going to have accidental exposure. It just happens, even to the most careful person,” Portnoy said. “If you’ve got a true, IgE food allergy, you should carry self-injectable epinephrine, even if you’ve only had hives before. The next time if you get a higher exposure, you may have a life-threatening reaction.”

Patients with food allergies should also wear a medical alert bracelet, he suggested. The guidelines further include recommendations for food allergy management in special settings and circumstances in which patients have an increased risk for unintentional food allergy exposure.

“From the perspective of schools and childcare, parents should partner with the administrative staff and teachers or childcare workers to determine what avoidance maneuvers may be lacking. It’s important they understand when acute care is needed, how to respond and when it’s appropriate to administer epinephrine,” Oppenheimer said.

Sections of the practice parameter discuss successful avoidance, risk factors and prevention of food allergy. Cross-reactivity of food allergy, adverse reactions to food additives, genetically modified foods and future directions also are highlighted. The guidelines also list the Food Allergy & Anaphylaxis Network (FAAN) as a resource for patient information on food avoidance.

“While some clinicians are very familiar with food allergy, others rarely see patients with this allergic disorder. The guidelines provide a comprehensive summary and will serve as a good reference tool for both groups of clinicians,” said Anne Munoz-Furlong, FAAN founder and chief executive officer. “Additionally, it will improve patient care.”

The Joint Task Force guidelines, “Food allergy: a practice parameter,” are published as a 68-page supplement to the Annals of Allergy, Asthma & Immunology. Members of the ACAAI, the American Academy of Allergy, Asthma and Immunology and the Joint Council of Allergy, Asthma and Immunology collaborated to devise the guidelines.

For more information:

• Chapman JA, Bernstein IL, Lee RE, et al. Food allergy: a practice parameter. Ann Allergy Asthma Immunol. 2006;96 (suppl 2):S1-S68.