I’m a pediatric dietitian, and families come to me with IgE test results from their family doctor. In many cases, there are several foods with moderate/high levels of IgE. If they are eating those foods and don’t have symptoms, should we restrict their diet?

No, the client would not need to restrict these foods. IgE antibodies mediate immediate hypersensitivity. The symptoms usually start within minutes, but can be delayed up to a few hours. The typical symptoms affect the skin (swelling, hives, itching), respiratory tract (wheezing, difficulty breathing) and the gastrointestinal tract (vomiting, diarrhea). Anaphylaxis is a severe reaction. Extremely high levels of food-specific IgE, indicates a high likelihood of an immediate reaction to that food. Unfortunately, the number that constitutes an extremely high level varies between allergens, has not been established for most allergens and varies with age. The clinical significance of a moderately high level of food specific IgE is questionable. In most cases, the patient can eat the food without reaction. Note: Many people still refer to RAST – which is the brand name of an outdated test. Food-specific serum IgE testing is the current name. Patients with suspected immediate food allergy should be assessed by a board certified allergist/clinical immunologist.
A good handout for patients is: Guidelines for the Diagnosis and Management of Food Allergy in the United States. Summary for Patients, Families, and Caregivers. Please read the paragraph under, Tests to identify foods causing your allergic reaction involving IgE (pg. 12). Table B on that page is a great summary.

Posted in: Spring2013-Q&A