Food-Sensitivity Panels and IgG Tests

What these tests are

A food-sensitivity panel is a blood (or finger-prick) test sold directly to consumers or through some practitioners. It reports levels of IgG antibodies, a type of immune protein, against many foods at once, usually 90 to 100 foods on a single panel. [1] Some panels list 200 targets or more. [2] The usual promise is that removing the foods with "high" results will ease symptoms.

This page covers the test, not your symptoms. If a food seems to make you ill, that is worth discussing with a clinician, and nothing here replaces that. Evidence labels used here are explained in How We Label Evidence in Biohacking.

What the evidence says

Label for IgG panels as a way to find food intolerance or allergy: no good evidence of benefit.

• The antibody is a sign of eating the food. The allergy society AAAAI says IgG is likely a normal response of the immune system to exposure to food, and higher IgG4 to a food may simply go with tolerance. [1] A laboratory-medicine society summary says the same: food-specific IgG is understood as a normal response to food in the diet. [2]
• Positive results without symptoms are common. A European allergy society (EAACI) task force noted that many serum samples show positive IgG4 results without matching symptoms. It concluded IgG4 to foods does not indicate allergy or intolerance but a physiological response to eating them. [3]
• Several societies advise against it. Quoted guidance includes: measuring food-specific IgG and IgG4 is not recommended for diagnosing non-IgE-mediated food-related allergic disorders (AAAAI and ACAAI), and there is no body of research supporting IgG testing to diagnose adverse reactions to food (Canadian society CSACI). [2]
• The supporting studies are weak. AAAAI states the test has never been scientifically proven to do what it claims, and that the studies offered in support are often out of date, in non-reputable journals, or did not use the test in question. [1]
• Public health advice. The NHS says some tests sold to diagnose food intolerance are not recommended: there is limited evidence they give accurate results and they may suggest avoiding multiple foods, which can be harmful. [4]

Why people feel better anyway

A panel that flags many foods can lead to a long avoidance list. The laboratory-medicine summary notes that people acting on such results may improve by coincidence, because the large number of foods removed may include the real culprit, and that over-restriction carries a risk of nutritional deficiencies and can harm quality of life. [2] Feeling better after a change is not proof that the test found the cause (see N-of-1 Research: Meaning and Limits).

Allergy, intolerance and sensitivity are different things

Who should be especially careful

• Anyone who has had a fast or severe reaction (swelling, breathing trouble, collapse) should seek urgent medical care and not rely on a panel. In the US, call 911.
• Children, people with a history of disordered eating, and people with other medical needs can be harmed by long avoidance lists. See Eating Disorders and Obsessive Tracking.
• Do not drop a food your clinician told you to keep, and do not stop medicines because of a panel result.

How to evaluate a panel before paying

• Ask which antibody is measured and what clinical outcome studies support acting on it. See Analytical Validity, Clinical Validity and Clinical Utility.
• Notice whether the company relies on testimonials rather than controlled trials.
• Read about other direct-to-consumer tests in Tests Sold in Integrative Practice.