What does the Immunoglobulin G Antibodies to Food Antigens test measure?

Why is Immunoglobulin G Antibodies to Food Antigens measured?

Proponents of IgG food-sensitivity testing argue that elevated IgG to specific foods may identify delayed, non-IgE-mediated adverse reactions contributing to gastrointestinal symptoms, headache, fatigue, and inflammatory conditions, and that dietary elimination guided by IgG results can reduce symptom burden. Mainstream allergy and gastroenterology societies, including the American Academy of Allergy, Asthma & Immunology and the European Academy of Allergy and Clinical Immunology, state that IgG antibodies to foods are a physiological response to exposure and do not predict clinical food intolerance or allergy, and should not be used to diagnose food-related symptoms. The test is positioned as a functional-medicine tool for personalised elimination-diet planning rather than a diagnostic standard of care.

Reference ranges

Standard reference

Laboratory-specific categorical classification: negative, borderline, mild, moderate, or elevated reactivity for each of 184 food antigens.

Functional medicine optimal

Not applicable. Results are reported as a reactivity profile across 184 antigens; interpretation is individualised, with higher-reactive foods considered candidates for therapeutic elimination trials. No universally accepted 'optimal' IgG titre exists.

Units

Arbitrary units (AU), U/mL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.