What role does IgG play in allergy?

IgG antibodies are often linked to food intolerances or delayed-type allergies (type III hypersensitivity), but the scientific evidence for a causal role is weak. While IgE clearly mediates immediate allergic reactions, IgG's role is controversial: many commercial tests claim that IgG against foods indicates an 'intolerance,' yet studies generally fail to show reproducible clinical relevance. In fact, elevated IgG levels can simply reflect normal immune exposure to common foods without causing symptoms. The German Society for Allergology and Clinical Immunology (DGAKI) advises against using IgG-based tests for allergy diagnosis. In the MyBody-X context, no specific IgG test is mentioned; if offered, its predictive value would be limited. For true allergies, IgE testing and clinical history remain the gold standard. Caveat: Do not rely on IgG results to make dietary changes, as this may lead to unnecessary restrictions.