Doubt cast on many reports of food allergies

By Ashton Daigle

A new medical report commissioned by the federal government has concluded that poorly done studies and misdiagnosis may be leading people to believe they have food allergies when they actually do not.

The report, published Wednesday in The Journal of the American Medical Association, is part of a large project organized by the National Institute of Allergy and Infectious Diseases in an effort to try to shed truth on the topic of food allergies.

“The report correctly finds that the public perception of food allergy may be somewhat exaggerated," Dr. Paul Detjen, MD, selected as a Chicago Top Doctor by TopTierMD as a top rated allergist and immunologist in Chicago, said. "Patients use the word 'allergy' loosely. Allergists use it to specifically refer to an immediate reaction to a food with itchy hives or anaphylaxis which is confirmed by an IgE skin test or IgE blood test, although the skin test is more physiologic.”

Dr. Joshua Boyce, an allergist and chairman of the guidelines committee, told the New York Times that one of the biggest misconceptions about food allergies is that a positive test for IgE antibodies to a food means a person is allergic to that food. Boyce said this isn’t necessarily the case.

Dr. Detjen agrees.

“Blood tests alone certainly do not suffice for the diagnosis of food allergy,” Dr. Detjen said. “This is not unlike many medical conditions, such as a high blood sugar or positive ANA, which alone do not diagnose diabetes or lupus. The context is required.”

Dr. Detjen said a diagnosis requires an allergic story confirmed by an IgE - allergic antibody - skin test or blood test.

“IgG blood testing - versus the allergic antibody IgE - is fraught with even more ambiguity,” Dr. Detjen said. “Many of us have positive levels of IgG antibody to some foods. However, the clinical relevance of these tests is far from certain.”

One method of testing for food allergies is to use a food challenge, in which people are given a suspect food that is disguised. If the disguised food causes a reaction, the person has an allergy. Riedl said many believe that the test is too time-consuming. Others, Riedl said, fear asking people to consume a food that could cause an allergic reaction.

Dr. Marc Riedl, the author of the paper, told the New York Times that there is no doubt people can have food allergies but noted that the true incidence of food allergies is approximately eight percent for children and less than five percent for adults.

Dr. Detjen said while food allergies may be exaggerated, they still should not be taken lightly.

"Food allergies are certainly more frequent than in decades past, both in children and adults," Dr. Detjen said.

Dr. Paul Detjen MD was selected in 2010 by TopTierMD as a Chicago Top Doctor - He was named a Best Chicago Allergy Immunology specializing in Allergic Rhinitis, and Food Allergies.  He practices in Kenilworth , IL and is affiliated with Evanston, Glenbrook, Children's Memorial,  University of Chicago, and Highland Park  Hospitals