Can IgG help with Müdigkeit?

Whether IgG tests help with fatigue is scientifically controversial. IgG (immunoglobulin G) is often marketed by direct-to-consumer companies as a marker for food intolerances that supposedly cause fatigue. However, IgG antibodies merely reflect a normal immune response to food proteins – they are not indicative of intolerance or allergy. Major medical organizations, including the European Academy of Allergy and Clinical Immunology, advise against using IgG tests for diagnosing food intolerances due to lack of evidence. Fatigue has many potential causes (sleep deprivation, stress, iron deficiency, thyroid issues, etc.), and a positive IgG result may lead to unnecessary dietary restrictions that risk nutritional deficiencies. The evidence for any benefit in fatigue is weak and largely based on marketing, not rigorous clinical trials. Caveat: IgG tests are not a substitute for medical evaluation. Evidence grade: marketing/unclear.