Evidence check: IgG in the context of allergy

IgG antibody testing for food sensitivities or allergies is widely marketed by direct-to-consumer labs, but it lacks scientific validation. IgG antibodies are a normal immune response to food proteins and do not indicate an allergy or intolerance. Mainstream allergy guidelines (e.g., EAACI, AAAAI) explicitly advise against using IgG tests for diagnosis, as they can lead to unnecessary dietary restrictions and nutritional deficiencies. True food allergies are mediated by IgE, and intolerances are diagnosed via clinical history, elimination diets, or specific tests like lactose hydrogen breath tests. No robust evidence supports the use of IgG testing to guide dietary choices. Evidence: marketing/unclear. Caveat: Relying on IgG results may cause harm through false positives and unnecessary avoidance of healthy foods.