What to watch with IgG and longevity?

The question about IgG and IgA in the context of longevity is nuanced. In practice, IgG and IgA tests are often marketed as 'food sensitivity tests,' but the scientific evidence is weak. Major allergy and immunology societies (e.g., EAACI, AAAAI) advise against IgG-based food sensitivity tests due to high false-positive rates and lack of clinical validity. IgA testing (e.g., tissue transglutaminase IgA) is well-established for celiac disease screening, but not for general longevity. For true longevity, better-validated biomarkers include hs-CRP, IL-6, HbA1c, and lipid profiles. Consumer DNA or blood tests for IgG/IgA are not supported by strong evidence for guiding diet or lifestyle. Caveat: Do not make major dietary changes based on these tests alone; consult a healthcare professional for personalized advice.