WebMD Medical News
Laura J. Martin, MD
Dec. 6, 2010 -- Comprehensive new guidelines on food allergies are out from the National Institute of Allergy and Infectious Diseases (NIAID).
The new guidelines are directed at doctors to help them diagnose and manage food allergies.
Experts say food allergies appear to be on the rise, affecting nearly 5% of children younger than 5 and about 4% of teens and adults.
''We hope the guidelines will help patients and family members work better with their physician'' to identify the causes of food allergies, said Matthew Fenton, PhD, chief of the asthma, allergy, and inflammation branch of the division of allergy, immunology and transplantation at NIAID. He spoke at a Friday news conference detailing the new guidelines and led the guidelines development project for NIAID.
The guidelines address diagnostic tests, treatment, and prevention, among other areas.
While the guidelines are aimed at doctors, it will help parents and those with food allergies to be aware of their existence, said Hugh Sampson, MD, professor of pediatrics at the Mount Sinai School of Medicine in New York, who serves on the guidelines coordinating committee and also spoke at the news conference. "When they see their physician or request a referral to an allergist, they should know what type of questions will be asked of them and have some idea of what kind of tests their physician will be doing."
A coordinating committee representing 34 professional medical organizations, advocacy groups, and federal agencies oversaw the guidelines development.
Then, a 25-member expert panel was selected; it pored over published literature and drew on clinical opinions to draft the guidelines.
Public comment was invited before the final guidelines were issued.
The guidelines define food allergy as "an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food."
It distinguishes allergies from intolerances. Foods that cause the same reproducible adverse reaction but don't have a likely or established immune system response are not considered allergies, but rather intolerances.
For instance, someone allergic to cow's milk due to an immune system response to milk protein has a food allergy. But someone who has a difficult time drinking milk due to an inability to digest the lactose in milk has a food intolerance.
Among the most common food allergies are reactions to:
Anaphylaxis, a serious allergic reaction that comes on rapidly and may cause death, can occur in response to food. Up to 65% of anaphylaxis cases are thought to be due to food.
Under the new guidelines, the panel of experts recommends that intradermal or skin testing should not be used to make a diagnosis of food allergy.
The experts recommend skin puncture tests, in which a small amount of the extract of a suspected food in placed on the skin, then the skin is punctured through the droplet, to help identify possible troublesome foods but not to make a diagnosis based on it alone.
It also recommends against the routine use of measuring total blood IgE, the antibody formed in reaction to an allergen.
It recommends allergen-specific IgE blood testing but cautions that the test results alone are not enough to make a diagnosis.
Food elimination diets -- taking away one or a few specific foods to see if the reaction disappears -- may help.
Oral food challenges -- exposing the person to the suspected food under medical supervision -- are thought to be helpful.
If exposure to a certain food triggers symptoms, the doctor should then see if that finding matches with lab tests and medical history.
Avoidance is best, the experts agree. They write: "There are nomedications currently recommended by the EP [expert panel] to prevent IgE-mediated food-induced allergic reactions from occurring in an individual with existing food allergies."
When food allergies trigger anaphylaxis, the experts recommend epinephrine injections first.
While some pregnant women may hope restricting their diets during pregnancy or during breastfeeding may help their children avoid allergies, the experts disagree and don't recommend this.
They don't recommend soy formula as a strategy for preventing the development of allergies, either.
A child with food allergies may outgrow them, Sampson said.
It depends on the food, partially. “If their child is allergic to egg, for example, chances are very good that children will outgrow it,” he said. “We know that about 80% will.” According to the guidelines, most children will eventually also tolerate milk, soy, and wheat.
Outgrowing tree nut and peanut allergies is much less common.
SOURCES:News conference, National Institute of Allergy and Infectious Diseases, Dec. 3, 2010.Matthew Fenton, PhD, chief of the asthma, allergy and inflammation branch, division of allergy, immunology and transplantation, National Institute of Allergy and Infectious Diseases, National Institutes of Health.Hugh A. Sampson, MD, professor of pediatrics, Mount Sinai School of Medicine, New York; director, Jaffe Food Allergy Institute.
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