MY FOODBOOK: which blood markers matter?

When asking which blood markers matter for a 'Foodbook', the answer depends on the purpose. For immediate-type food allergies, specific IgE antibodies are the gold standard – clinically validated and used by allergists. In contrast, IgG blood markers, often marketed as 'food sensitivity' tests, lack scientific validation for diagnosing intolerances or allergies; medical societies advise against them because they reflect immune exposure, not disease. For lactose intolerance, the hydrogen breath test is standard, not a blood marker. Celiac disease requires specific antibodies (tTG-IgA) and duodenal biopsy. MyBody-X DNA tests analyze genetic predispositions (e.g., HLA-DQ2/DQ8 for celiac, LCT variants for lactose), but these do not replace blood tests. A meaningful Foodbook should rely on validated blood markers (IgE, tTG-IgA) and clinical diagnosis, not non-evidence-based IgG panels. Evidence is mixed: strong for IgE, weak to absent for IgG. Safety note: Without medical guidance, false positives or negatives can lead to unnecessary dietary restrictions or missed diagnoses.