How are IgG and allergy related?

IgG and allergy are not directly equivalent. Classic immediate-type allergies (Type I) are mediated by IgE antibodies, not IgG. IgG, particularly IgG4, is often linked to food intolerances or tolerance mechanisms. Some direct-to-consumer tests measure IgG against foods and claim to identify intolerances. However, the scientific evidence is weak: elevated IgG levels can simply reflect normal immune exposure to frequently eaten foods and are not reliable markers for clinical intolerance. The German Society for Allergology and Clinical Immunology (DGAKI) advises against such tests. From MyBody-X's perspective: IgG tests are not part of the standard offering; the focus is on IgE-mediated allergies, genetics, and microbiome. If an allergy is suspected, an IgE test by a physician is recommended. Caveat: self-tests without medical guidance can lead to unnecessary dietary restrictions or misinterpretations.