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Food Intolerance Testing--Investigate or Denigrate?  

I sat across from Ellen in the exam room.  Her once-tired face had been replaced by a vibrant smile.  "I feel better than I have in years", said Ellen.  Her energy, stamina had returned and her constant gastrointestinal complaints had vanished.  

She handed me an article, and somewhat sheepishly said, "I think you might want to see this".  It was an article from the StarTribune Lifestyle section, called "Doubts cast on food intolerance testing."   

"I know your advice has worked for me", she said.  "But what can I tell other peope after they've read this article?"


Through a combination of detailed history-taking, open- challenge testing here at our office, AND IgG testing, I had diagnosed Ellen as having delayed-type food sensitivities. 

The article mentioned casts doubt on the utility of IgG testing in the diagnosis of delayed-onset of food sensitivity.  But in doing so, I think it misses a few key points. As an allergist with 30 years of experience in diagnosing and treating this troublesome problem, and with extensive experience in looking over hundreds of IgG food tests,  let me weigh in with a caveats:

In Vitro Food Tests should never be utilized alone  to diagnose food sensitivities.  Results should  only be interpreted in conjunction with a thorough history taken by an experienced clinician.  Period.  

False positives occur with IgG food allergy testing.  In reviewing hundreds of these tests, and comparing them to later open food challenges, false positives do indeed occur.  The experienced clinician will often be able to spot these on an initial review of the test results.  

Despite the above, the IgG food testing results often give an excellent "starting point" to begin to look for delayed food sensitivities in a chronically ill patient.  It is an excellent screening tool.

The IgG ELISA/RAST can be cost-effective if done properly.  In our lab, we run a "targeted" IgG RAST to selected foods, based upon the patient's history AND the experienced physician's impressions.  Why check for blueberry allergy, for example, if the patient doesn't even know what a blueberry IS?     

It is the height of hypocrisy for the allergy community to criticize this test, when not admitting they don't have a diagnostic solution to the problem, and aren't even interested in pursuing it.  Hiding behind the IgE food-allergy mantra is a smokescreen to distract us from a much bigger problem--and that is that delayed onset food sensitivities are (in my humble opinion) at least as important in scope as IgE mediated food sensitivities.  Just because a food makes a patient sick hours after eating it, and not immediately, and just because the food sensitivity is non-IgE mediated, should we be uninterested?  As part of the Renaissance in our profession, we need to be the masters of ALL food reactions.  

In truth, the patient who doesn't know about delayed-onset food allergy is uninformed, and the patient who sees the allergist and asks about dellayed-onset food allergy usually leaves misinformed.

Delayed-onset food allergy.  IgG testing.  Something to investigate.  Not denigrate.

Later, Dude




Posted on Sunday, April 29, 2012 at 05:55PM by Registered CommenterGeorge F Kroker MD FACAAI | CommentsPost a Comment

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