IgG food sensitivity tests
IgG food-sensitivity panels claim to identify food intolerances from a blood test. The antibodies they measure mostly show which foods you eat often, allergy societies advise against the tests, and they prompt diets that narrow nutrition for no proven gain.
Don't buy one. If you have irritable bowel syndrome, the one condition where the idea has shown a signal, take the question to a gastroenterologist rather than a consumer panel.
What the test measures
These panels measure immunoglobulin G (IgG) antibodies, and sometimes the IgG4 subclass, against foods. Their premise, that food-specific IgG antibodies indicate intolerance, gets the immunology backwards.
Food-specific IgG and IgG4 mostly reflect normal exposure to, and tolerance of, foods you eat often.[1] A rise in IgG4 is even one of the typical immune changes during oral immunotherapy for genuine (IgE-mediated) food allergy, the treatment that builds tolerance to a food.[2] A high result is closer to a record of your usual diet than a warning.
What allergy societies say
The Canadian Society of Allergy and Clinical Immunology strongly discourages IgG testing to identify or predict adverse reactions to food.[3] The American Academy of Allergy, Asthma & Immunology and the European Academy of Allergy and Clinical Immunology advise against it for diagnosing food allergy or intolerance.[4]
The harm is the diet that follows
In people without symptoms, a positive result mostly reflects foods eaten often. The elimination diets it prompts narrow nutrition and strain social eating for no proven gain.
The one signal: irritable bowel syndrome
The idea has shown a signal in one place. In a sham-controlled trial of 223 people with irritable bowel syndrome (IBS) who had already tested IgG-positive, about 60% of those on an IgG-guided elimination diet had their abdominal pain fall by at least 30%, against 42% of those on a sham diet.[5] The trial used a purpose-built 18-food assay, not a consumer panel, and enrolled only people with IBS. That makes it a question for a gastroenterologist, not a reason for a healthy adult to buy a panel.
What to do
- Skip consumer IgG and IgG4 food panels. Which tests do earn a place is covered on Midlife labs.
- Don't cut foods out on the strength of one. A high result mostly means you eat that food often.
- With IBS symptoms, see a gastroenterologist. The positive trial used a purpose-built 18-food test, not a consumer panel, and only in people with IBS.
Further reading
- Stapel SO et al. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy 2008.[6]
- Carr S et al. CSACI Position statement on the testing of food-specific IgG. Allergy Asthma Clin Immunol 2012.[7]
- Singh P et al. A Novel, IBS-Specific IgG ELISA-Based Elimination Diet in Irritable Bowel Syndrome: A Randomized, Sham-Controlled Trial. Gastroenterology 2025.[8]