CSACI Position statement on the testing of food-specific IgG

The Canadian Society of Allergy and Clinical Immunology (CSACI) is very concerned about the increased marketing of food-specific immunoglobulin G (IgG) testing towards the general public over the past few years, supposedly as a simple means by which to identify “food sensitivity”, food intolerance or food allergies. In the past, this unvalidated form of testing was usually offered by alternative or complementary health providers, but has now become more widely available with direct-to-consumer marketing through a nationwide chain of pharmacies.

There is no body of research that supports the use of this test to diagnose adverse reactions to food or to predict future adverse reactions. The literature currently suggests that the presence of specific IgG to food is a marker of exposure and tolerance to food, as seen in those participating in oral immunotherapy studies. Hence, positive test results for food-specific IgG are to be expected in normal, healthy adults and children. Furthermore, the inappropriate use of this test only increases the likelihood of false diagnoses being made, resulting in unnecessary dietary restrictions and decreased quality of life. The immediate expense of the test to individuals (see below for details on cost) will be compounded by the costs incurred by an already-overburdened health care system. Confused by the information provided by IgG testing, individuals are likely to request additional specialist referrals and investigations which would otherwise not be necessary.

Additionally, and perhaps of greater potential concern, a person with a true immunoglobulin E (IgE)-mediated food allergy, who is at significant risk for life-threatening anaphylaxis, may very well not have elevated levels of specific IgG to their particular allergen, and may be inappropriately advised to reintroduce this potentially deadly item into their diet.

As a result of these serious and growing concerns, the CSACI has elected to issue a formal statement supporting the opinions expressed by the American Academy of Allergy Asthma and Immunology (AAAAI) [1], and by the European Academy of Allergy and Clinical Immunology (EAACI) [2]. Both of these organizations warn about the inappropriate measurement of food-specific IgG or IgG4 to suggest the presence or potential of adverse reactions to food. Recent guidelines emphasize that such testing plays no role in the diagnosis of food allergy or intolerance [3]. A recent Canadian publication also elaborates similar concerns from the perspective of community allergy practice [4].