Short answer: there isn’t a single reliable “food sensitivity” blood test for vague or delayed food reactions. Many commercial IgG panels are not supported by evidence. Instead use evidence-based tests matched to the problem you suspect and/or work with an allergist and a registered dietitian (RDN). What to use depending on what you mean Suspect immediate (allergic) reactions — hives, throat tightness, wheeze, anaphylaxis: Skin-prick testing performed by a board‑certified allergist (standard of care). Serum specific‑IgE testing (ImmunoCAP / Thermo Fisher Phadia is the widely used, validated lab assay). If results are unclear, a medically supervised oral food challenge is the gold standard. Suspect food intolerance (non‑immune digestion problems) — bloating, gas, diarrhea: Lactose or fructose intolerance: breath hydrogen/methane tests (typically done through a GI clinic or reputable lab such as Genova Diagnostics). Suspected SIBO: lactulose or glucose breath tests performed by a GI clinic or functional lab (Genova Diagnostics offers these). Celiac disease: tissue transglutaminase IgA (tTG‑IgA) serology — available through major clinical labs (Quest Diagnostics, Labcorp). If positive (or high suspicion) follow up with GI for biopsy/HLA testing. Suspect non‑celiac gluten sensitivity or delayed, nonspecific symptoms: There is no validated lab test. The best approach is an elimination diet with careful re‑challenge under the guidance of an RDN and/or physician. What to avoid IgG or IgG4 “food sensitivity” panels sold direct‑to‑consumer (examples: Everlywell food sensitivity IgG test, many large 100+ item IgG panels, YorkTest in the UK, and similar offerings). Professional societies (allergy and immunology groups) advise against using IgG for diagnosing intolerance or allergy because IgG generally indicates exposure, not clinically relevant sensitivity. Broad “food intolerance” or microbiome panels that promise to pinpoint problem foods without clinical correlation — these lack good validation. Services/brands I’d recommend (by role) Allergist/immunology testing: see a board‑certified allergist for skin testing and, if needed, ImmunoCAP (Thermo Fisher/Phadia) specific‑IgE blood testing. Celiac/inflammatory testing: Quest Diagnostics or Labcorp for tTG‑IgA and follow‑up testing. Breath testing and functional GI testing: Genova Diagnostics is a reputable clinical lab that offers lactose/fructose and SIBO breath testing and stool testing used by gastroenterologists and practitioners. Diet management: work with a Registered Dietitian Nutritionist (RDN) experienced in food allergies/intolerances or gastrointestinal disorders for supervised elimination/rechallenge. Ask your gastroenterologist or allergist for a referral, or find an RDN through the Academy of Nutrition and Dietetics. Bottom line If you’re worried about a potentially dangerous allergic reaction, see an allergist (skin testing / ImmunoCAP and/or oral challenge). If your symptoms are gastrointestinal, get targeted breath tests or celiac serology through a GI clinic or reputable lab and do an elimination diet with an RDN. Avoid commercial IgG “food sensitivity” panels — they’re commonly misleading. If you tell me the symptoms you’re getting (timing, type, severity), I can recommend the most appropriate specific test and who to see.
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