How are IgG and Allergie related?

The relationship between IgG and allergies is nuanced and often misunderstood. IgE antibodies mediate classic immediate-type (Type I) allergies, while IgG antibodies are involved in delayed immune responses and tolerance. IgG4, in particular, is associated with the development of tolerance to allergens, for example during allergen-specific immunotherapy. Many direct-to-consumer tests claim that measuring IgG against foods can uncover 'hidden allergies' or intolerances. However, the scientific evidence for this is weak: detected IgG levels often reflect a normal immune response to common foods rather than a pathological reaction. Professional societies such as the European Academy of Allergy and Clinical Immunology advise against using IgG tests for allergy diagnosis. A positive IgG result alone does not justify dietary restrictions. For suspected true allergy, IgE testing, skin prick tests, and clinical history remain the gold standard. MyBody-X does not offer IgG-based allergy tests; the evidence level is 'mixed' – mechanistically plausible but clinically insufficiently validated for consumer use.