Food intolerance tests
The marketing of intolerance tests for various foodstuffs and nutrients continues to increase. During food intolerance testing, blood is exposed in vitro to a panel of foodstuffs and food components (5). The degree of total immunoglobulin G (IgG) antibody binding to each food is quantified via an enzyme- or fluorescence-linked immunosorbent assay. Alternatively, IgG subclass 4 (IgG4) binding can be measured instead of total IgG. Some of the food intolerance tests also measure both food-specific IgG4 and food-specific immunoglobulin E (IgE) levels in a wide range of foodstuffs, which can be confusing for patients purchasing the tests (5).
Children are unnecessarily being put on elimination diets without adequate investigation taking place
Several countries have expressed concern about the increased marketing of food-specific IgG testing to the general public in recent years, purportedly as a simple way of identifying food intolerances and food allergies (6–9). Uncritical and inappropriate use of such tests increases the likelihood of false diagnoses, resulting in unnecessary dietary restrictions and reduced quality of life (10). Concerned parents might put children on exclusion diets that pose a risk of poor growth and malnutrition (6). Such diets can entail the elimination of dairy products, wheat, eggs and/or other foodstuffs found in healthy, balanced diets. Updated guidelines therefore list food-specific IgG4 testing as a non-standardised and unprovoked procedure, along with other tests such as hair analysis, cytotoxicity assays and electrodermal testing (6–8).
The literature indicates that food-specific IgG presence is a marker of food exposure and tolerance (6–9). Positive test results for food-specific IgG can therefore be expected in normal, healthy children.