Food IgG Sensitivity and Intolerance Tests: What They Measure and What Allergy Societies Say

Urgent first

Sudden swelling of the lips, mouth or throat, trouble breathing, a tight throat, or fainting after eating can be a severe allergic reaction. In the US call 911. The NHS lists the same signs as an emergency in the UK. [1] A food IgG result cannot rule out a true allergy. This page is information only and does not replace medical care.

What the test is

A food IgG panel is a blood test that reports IgG antibodies to a list of foods, sometimes dozens or hundreds. It is sold direct to consumers and offered by some practitioners, including medical, naturopathic, nutrition and coaching practices, to find "food sensitivities" or "hidden intolerances." IgG is a common type of antibody. It is not the same antibody type (IgE) that is measured in allergy blood tests. [2]

What the test measures

The Canadian Society of Allergy and Clinical Immunology (CSACI) states that the literature suggests that specific IgG to food is a marker of exposure and tolerance to food, so positive results are to be expected in normal, healthy adults and children. [3] A European Academy of Allergy and Clinical Immunology (EAACI) task force reached a similar conclusion for IgG4: it indicates repeated exposure to food components and a physiological response, not food allergy or intolerance. [4] In plain terms, having IgG to a food you eat often is usually normal.

What allergy societies say

• CSACI "strongly discourages" food-specific IgG testing to identify or predict adverse reactions to food. [3]
• The EAACI task force considered IgG4 testing to foods irrelevant for the laboratory work-up of food allergy or intolerance and said it should not be performed for food-related complaints. [4]
• The EAACI report also found a lack of controlled studies on the diagnostic value of IgG4 testing in food allergy. [4]

Both statements are from 2008 and 2012. We did not search for newer position statements beyond these, so we do not claim there are none.

Possible harms

CSACI warns that a person with a true IgE-mediated food allergy, who is at risk of life-threatening anaphylaxis, may not have elevated IgG to the allergen and may be inappropriately advised to reintroduce the food. [3] It adds that inappropriate use only increases the likelihood of false diagnoses, with unnecessary dietary restrictions and reduced quality of life. [3] The NHS says tests bought to diagnose food intolerance are not recommended, because there is limited evidence they give accurate results and they may suggest avoiding multiple foods, which can be harmful. [5] We did not find a readable source with figures on how often people harm their nutrition this way, so we give none.

How allergy and intolerance are actually assessed

Food allergy is an immune reaction. MedlinePlus lists skin prick tests, IgE allergy blood tests and, in some cases, supervised elimination diets or food challenges, chosen by an allergist or provider for your symptoms. [2] It notes that these tests are usually ordered if there have been symptoms of an allergy, because in people without symptoms they can show signs of an allergy when there isn't one. [2] Food intolerance is a separate problem, often digestive. The NHS says a GP may arrange tests such as a trial diet that avoids the suspected food and then reintroduces it, blood tests, or a breath test for lactose intolerance, and may ask for a food and symptoms diary. [5] MedlinePlus warns that an oral food challenge can cause a severe allergic reaction and is done under close supervision by an allergist, and that an elimination diet may also cause a serious allergic reaction. [2] We give no elimination plan here.

Evidence summary

If you think foods bother you

Keep a simple record of what you ate and what you felt, and take it to a doctor. Do not drop whole food groups, and do not stop or change prescribed medicines. Children, pregnant people, older adults and anyone with an eating-disorder history should get advice from a clinician or dietitian before restricting foods. See leaky gut cleanses and gut tests for related gut claims.

Related reading

The overview of all such tests is tests sold in integrative practice. The Biohacking guide is food-sensitivity panels and IgG tests. The shorter claim check is food sensitivity tests find your trigger foods. For how to judge any test, see how to evaluate a therapy claim.