Six Reasons I Don’t Recommend IgG Food Testing

Updated: January 2020

IgGFood sensitivity testing gives specific answers, so it is popular with clients and practitioners. Unfortunately, each test gives a different answer, and we don’t have proper studies to know which test (if any) is the most accurate. Each company claims they have research to prove they have the “gold standard” in food sensitivity testing, but when you take a close look, the research does not support their claims.

IgG testing is the most common food sensitivity test. Here are six reasons that I don’t recommend it.  

  • Research does not support it. The majority of studies published over the last few decades have not been supportive. The few positive results have primarily been open studies, which is a “group testimonial,” not a research study.
  • Every lab has a different procedure, which gives different answers. Each lab claims they have the best procedure. Sheryl Miller, from the Bastyr University Health Clinic, wrote an excellent analysis.
  • Many labs use outdated technology. A few years ago, I called several laboratories to prepare for a presentation on food sensitivity testing at the Dietitians of Canada conference. An employee at one of the labs was open and honest. The employee revealed that the company developed their technique to measure IgG antibodies in the 1980s (and had not updated it since). He agreed that antibody testing had improved substantially in the last 40 years. When I asked why they were selling a test based on outdated technology, he said that it was very popular with practitioners. In other words, the test was making money.
  • We all have food-specific IgG in our blood. Everyone that takes the test will have “problem” foods identified. One company advertised that 45% of the population has a food intolerance. How does a test that is 100% positive, find the 45% that have a food intolerance?
  • IgG is part of the food tolerance process. Researchers have identified four subtypes. IgG4 is related to food tolerance. For example, someone with an anaphylactic peanut allergy has peanut-IgE in their blood. When a person develops tolerance, peanut IgE decreases and peanut IgG4 goes up (indicating that IgG4 is necessary for food tolerance). Some companies report a combined value for both IgE and IgG – which does not make any sense!
  • Testing may lead to malnutrition and fear about eating. I am very passionate about this topic because of my work helping clients calm food fears and expand their diet. Test results often confirm the client’s suspicion that food is “bad.”. Long food avoidance lists make a nutritious diet difficult. Furthermore, people often get different tests and avoidance lists, so they don’t know what to eat!      
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2 comments on “Six Reasons I Don’t Recommend IgG Food Testing
  1. Wendy says:

    Thanks Andrea!

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