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IgG Food Sensitivity Tests
You finger-prick a kit, mail the tube, and two weeks later a colour-coded report says the dairy, wheat, and eggs in your normal diet are "reactive" and should go. The catch is the antibody it counts. IgG to food goes up in everyone who eats, and immunology's best reading of it is that it marks tolerance, not trouble. Every major allergy society tells doctors not to order it. Skip the test, keep the money, and you lose nothing real.
Avoid ยท As-needed Evidence Strong Chapter Food

The report looks like your shopping list because it is one. IgG antibodies to food are how a normal immune system remembers what you eat: protein crosses the gut, a B cell logs it, the antibody count climbs. People who drink milk daily score high on milk; vegans come back clean on egg and dairy. The subclass these panels read, IgG4, is the marker that rises when an allergic kid is slowly desensitised to peanut 1. A high score tracks how much of a food you eat 2.

The whole allergy field lines up against it. The American, European, Canadian, and Australasian societies each name IgG food testing as unproven and tell doctors to skip it 3245. The one trial proponents cite was manufacturer-funded, faded once dropouts were counted, and cut wheat and dairy that ease gut symptoms for reasons unrelated to IgG 67. The same design run in migraine found no difference from a random food list 8. Split one blood sample between two labs and the "reactive" lists come back visibly different 9.

Don't order the panel. Match the workup to the symptom instead.

What eating the "reactive" foods again looks like.

  • Days: nothing happens. Most of those foods were never the problem 2.
  • Weeks: meals stop being an audit; you accept the lunch invite.
  • Months: iron and B12 on a routine draw read normal; clothes fit.
  • Then the real work: a proper workup finds the treatable thing the panel was hiding, or names stress and sleep as the cause.
The fine print โ€” when to skip it, and what people get wrong

A report cuts 15 to 40 foods at once: malnutrition in kids 4, disordered eating in teens and young women 12, and months of delay before the real diagnosis lands 2.

"It's the delayed kind of allergy": no such IgG-mediated food allergy exists 13. "It's intolerance, then": real intolerances need a breath test, biopsy, or structured elimination, never an IgG panel 11.

References
  1. 1Aalberse RC, Stapel SO, Schuurman J, Rispens T (2009). Immunoglobulin G4: an odd antibody. Clinical & Experimental Allergy. link
  2. 2Stapel SO, Asero R, Ballmer-Weber BK, Knol EF, Strobel S, Vieths S, Kleine-Tebbe J (2008). Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. link
  3. 3AAAAI (2019). Choosing Wisely: Don't perform unproven diagnostic tests, such as immunoglobulin G (IgG) testing or an indiscriminate battery of immunoglobulin E (IgE) tests, in the evaluation of allergy. link
  4. 4Carr S, Chan E, Lavine E, Moote W (2012). CSACI Position statement on the testing of food-specific IgG. Allergy, Asthma & Clinical Immunology. link
  5. 5ASCIA (2023). ASCIA Position Statement: Unorthodox Testing and Treatment for Allergic Disorders. link
  6. 6Atkinson W, Sheldon TA, Shaath N, Whorwell PJ (2004). Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial. Gut. link
  7. 7Hunter JO (2005). Food elimination in IBS: the case for IgG testing remains doubtful. Gut. link
  8. 8Mitchell N, Hewitt CE, Jayakody S, Islam M, Adamson J, Watt I, Torgerson DJ (2011). Randomised controlled trial of food elimination diet based on IgG antibodies for the prevention of migraine like headaches. Nutrition Journal. link
  9. 9Mullin GE, Swift KM, Lipski L, Turnbull LK, Rampertab SD (2010). Testing for food reactions: the good, the bad, and the ugly. Nutrition in Clinical Practice. link
  10. 10Sicherer SH, Sampson HA (2018). Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management. Journal of Allergy and Clinical Immunology. link
  11. 11Lomer MCE (2015). Review article: the aetiology, diagnosis, mechanisms and clinical evidence for food intolerance. Alimentary Pharmacology & Therapeutics. link
  12. 12Hammond C, Lieberman JA (2018). Unproven Diagnostic Tests for Food Allergy. Immunology and Allergy Clinics of North America. link
  13. 13Kelso JM (2018). Unproven Diagnostic Tests for Adverse Reactions to Foods. The Journal of Allergy and Clinical Immunology: In Practice. link
Related in the handbook (9)
Alternatives
  • โ€” This is the legitimate alternative to IgG testing: watch what actually happens as you remove and re-add foods.
  • โ€” For gluten specifically, skip the IgG panel: the HLA-DQ2/DQ8 gene test can rule celiac out for life in one draw.
Related
  • โ€” Before a costly IgG panel, a real food-reaction mechanism like this is worth ruling out โ€” the test can't see it.
  • โ€” If you're tempted by a food-sensitivity panel for your gut, know it can't diagnose IBS โ€” a proper workup and structured diet can.
  • โ€” Both are ways healthy people get turned into patients โ€” a borderline 'flag' or a meaningless positive sending you down a needless cascade.
  • โ€” Both get sold as the hidden cause of vague symptoms; the IgG test is the panel 'leaky gut' clinics love to order.
  • โ€” Same trap, different aisle โ€” a marketed test most every medical society says to skip, sold as personalized insight.
  • โ€” An IgG panel will often flag wheat โ€” but it can't tell you whether gluten is really your problem.
  • โ€” Same playbook as IgG food tests: real biology underneath, thin proof the result changes anything, and a supplement upsell on the last page.
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