5 Reasons I Don’t Recommend IgG Food Testing


IgG food testing is popular, but that does not make it reliable! Read on for some facts that your practitioner won’t tell you.

Food sensitivity testing is popular with clients and practitioners. Clients like an exact list of foods they can and cannot eat. The problem is that every food sensitivity test gives a different answer. It’s hard to know which one (if any) is the most accurate. Many different testing methods are available, but I’ll focus on IgG testing in this article because it is the most common. Here are five reasons that I don’t recommend IgG testing.

Research does not support it.

Several research studies have been published over the last few decades and a few new ones continue to be published each year. The vast majority have not been supportive. The few with positive results have mostly been “open” studies. In other words, everyone gets the test and report they feel better. This is a “group testimonial”, not a research study.

Every lab has their own procedure, which gives different answers.

The lab procedures for IgG testing are not standardized, and each lab claims they have the best procedure. If a blood sample is sent to different labs, there will be different results. An excellent analysis was written by Sheryl Miller with the Bastyr University Health Clinic.

Many labs use outdated technology.

Here’s an example of a conversation with one lab. The employee revealed that their technique to measure IgG antibodies was developed in the 1980's (and had not updated it since). He agreed that many improvements in antibody testing have been made 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 When I asked why they were selling a test based on outdated technology, he said that it was very popular with practitioners. The popularity would likely decrease, if practitioners knew more about the test.

IgG is part of the process of food tolerance.

Everyone has IgG to a variety of food in their blood. Four subtypes have been identified. IgG4 is involved in food tolerance. If a person has an anaphylactic reaction to a food, their body is making IgE to that food. For example, someone with an anaphylactic peanut allergy will have peanut-IgE in their blood. If the peanut-IgE decreases, this indicates the body may be starting to tolerate peanut. Several research studies have shown that as IgE to a food goes down, IgG4 goes up (and the likely conclusion is that IgG4 is necessary for food tolerance). However, the exact role of the other IgG subtypes is not understood, so there is still a lot to learn. Some companies report a combined value for both IgE and IgG4 – which does not make any sense!

Testing leads to malnutrition and fear about eating.

I am very passionate about this topic, because of my work with clients on restricted diets. Clients will often show me lists they have received over the years from a variety of food sensitivity tests– each list suggesting different foods to avoid. This leads to restricted diets and malnutrition. More importantly, it changes a client’s perception about food. In extreme cases, it can lead to food phobia.

Not sure what to eat? I can help you live well with food sensitivities.

2 comments on “5 Reasons I Don’t Recommend IgG Food Testing
  1. Wendy says:

    Thanks Andrea!

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