Understanding IgG Testing:

IgG testing, also known as food-specific IgG testing, involves measuring levels of IgG antibodies in response to various foods. The theory behind IgG testing is that elevated IgG levels to certain foods indicate a sensitivity or intolerance to those foods, which may contribute to various health issues such as inflammation, digestive problems, and more.

The Lack of Scientific Validity:

Despite its widespread use, IgG testing has been widely criticised within the scientific and medical communities for several reasons. One of the primary concerns is the lack of scientific evidence supporting its validity and reliability. Numerous studies have shown that IgG levels can fluctuate based on factors unrelated to food sensitivity, such as age, genetics, and overall health status.

A comprehensive review published in the Journal of Allergy and Clinical Immunology concluded that there is insufficient evidence to support the use of IgG testing for diagnosing food sensitivities or guiding dietary recommendations. Similarly, a study published in the journal Food and Nutrition Research found no association between IgG levels and clinical symptoms in individuals with self reported food intolerance.

The Pitfalls of IgG Testing:

Additionally, IgG testing suffers from several inherent limitations and pitfalls that further undermine its reliability as a diagnostic tool. One major issue is the lack of standardisation and consistency among different testing methods and laboratories. There is significant variability in IgG test results depending on the testing protocol, the type of food antigens included in the panel, and the laboratory performing the analysis.

Furthermore, IgG testing often produces false positive results, leading individuals to unnecessarily restrict their diets based on foods that may not actually be problematic for them. This can result in nutritional deficiencies, disordered eating behaviours, and unnecessary stress and anxiety surrounding food choices.

The Importance of Evidence Based Practice:

As an evidence based practitioner, it is essential that I prioritise scientifically validated methods and interventions in my approach to nutrition counselling. While food sensitivities and intolerances are legitimate concerns for many individuals, IgG testing is not the solution.

Instead, we must rely on proven methods for identifying and managing food sensitivities, such as elimination diets, food diaries, and symptom tracking. These approaches are supported by robust scientific evidence and provide a more accurate and individualised assessment of food intolerances.

In conclusion, IgG testing is not evidence based and should not be used as a basis for dietary recommendations or clinical decision making. Despite its widespread use, IgG testing lacks scientific validity, suffers from inherent limitations and pitfalls, and may lead to unnecessary dietary restrictions and health risks.

As evidence based practitioners, we must advocate for the use of scientifically validated methods for identifying and managing food sensitivities, prioritising the health and wellbeing of our clients above all else. By staying true to the principles of evidence based practice, we can ensure that our interventions are grounded in science and ultimately contribute to better outcomes for our clients.

References:

• Stapel, S. O., Asero, R., Ballmer-Weber, B. K., Knol, E. F., Strobel, S., Vieths, S., & Kleine-Tebbe, J. (2008). Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy, 63(7), 793-796.
• Järvinen, K. M., & Westfall, J. E. (2012). Severe, immediate reactions to ingested egg: an update. Journal of Pediatric Allergy and Immunology, 23(4), 319-320.
• Boyce, J. A., & Assa'ad, A. (2010). Burks A W. Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel. Journal of Allergy and Clinical Immunology, 126(6), S1-S58.
• Gupta, R. S., Warren, C. M., Smith, B. M., Jiang, J., Blumenstock, J. A., Davis, M. M., & Schleimer, R. P. (2018). Prevalence and Severity of Food Allergies Among US Adults. JAMA Network Open, 1(4), e180485.
• Shreffler, W. G., Lencer, D. A., Bardina, L., Sampson, H. A., Knipe, D. M., & Kapschull, P. J. (2014). IgE and IgG4 Epitope Mapping by Microarray Immunoassay Reveals the Diversity of Immune Response to the Peanut Allergen, Ara h 2. Journal of Allergy and Clinical Immunology, 133(2), AB73.
• IgE and IgG4 Epitope Mapping by Microarray Immunoassay Reveals the Diversity of Immune Response to the Peanut Allergen, Ara h 2. (2014). Journal of Allergy and Clinical Immunology, 133(2), AB73.

By adhering to evidence based practices and steering clear of unsupported testing methods like IgG testing, we can uphold the integrity of our profession and provide the best possible care for our clients.