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What You Need to Know About Food Sensitivity Testing

By Elizabeth Herrin, MS, RD, LD

Are you trying to find new ways to improve your health for the new year? Maybe your resolution is to finally tackle your chronic GI symptoms like gas, bloating, and constipation. Maybe you’re wondering if food sensitivity testing will help you achieve your goals.

There is a lot of hype around food sensitivity testing these days. For those suffering from IBS or other GI symptoms, it sounds almost too good to be true: it will, allegedly, identify individual foods that cause symptoms and/or inflammation in your gut. It can differentiate between wheat and rye, between asparagus and broccoli. Instead of taking weeks or months doing elimination diets, you can do one blood test and have all the results at your fingertips.

How does food sensitivity testing work?

First, it’s important to understand that there are different kinds of food sensitivity tests. For this post, we will focus on one of the more common types of testing: IgG antibody testing. Our bodies make several kinds of antibodies to help keep us healthy. The kind you may be most familiar with are IgE antibodies, which cause allergic reaction symptoms like throat swelling, hives, and rashes. IgG on the other hand have a more delayed action, sometimes taking hours before causing a reaction, and cause symptoms like gas, bloating, constipation, or diarrhea.

These food sensitivity tests measure IgG antibodies and rank them on a scale of none, low, medium, or high. The idea is that many people’s IBS symptoms are actually caused by IgG reactions. That would mean that, in theory, we can test for these antibodies, remove the foods that are reactive, and relieve the symptoms.

It is possible to get false positive or false negative results on these tests. Antibodies are only created after exposure to foods. Therefore, if you have already eliminated a problem food, it may not flag as positive on a test because you aren’t actively creating antibodies. Occasionally, IgG antibodies can also be created as a normal physiologic response to foods. This means that you may have a food flagged on your test that does not cause symptoms. This is why it is important to follow both the elimination and reintroduction instructions given to you by your doctor or dietitian.

Who can benefit from food sensitivity testing?

Anyone can get food sensitivity testing done. However, those experiencing GI symptoms like gas, bloating or diarrhea will be most likely to benefit. IBS patients may find food sensitivity testing to be a faster alternative to food journaling and one by one elimination diets to determine their trigger foods. Additionally, food sensitivity testing may be beneficial for those suffering from food triggered migraine headaches.

What does the research say?

To understand the research, it is important to recognize that a food sensitivity is not the same thing as a food allergy. The literature tells us that IgG antibody reactions to foods are NOT associated with food allergies.

There is not a lot of research on food sensitivity testing in humans, though there are studies that support an association between elimination of flagged foods and an improvement in symptoms.  Additionally, a literature review conducted in 2019 found that food sensitivity testing may be beneficial for those suffering from migraines.

The bottom line: While it cannot be proven that food sensitivity testing identifies food intolerances or sensitivities, some studies show a relationship between symptom relief and food elimination following testing. With current research, we cannot completely exclude the possibility that some IgG reactions are a normal response to foods.


Geiselman, J.F. The Clinical Use of IgG Food Sensitivity Testing with Migraine Headache Patients: a Literature Review. Curr Pain Headache Rep 23, 79 (2019).

M. Woolger, J. , Lopez, J. , B. Melillo, A. , Tiozzo, E. , Alonso, Y. , Rafatjah, S. , Sarabia, A. , M. Leonard, S. , G. Long, E. , Schoor, M. , Tannenbaum, J. , Konefal, J. and E. Lewis, J. (2013) Improving quality of life in self-reported gastrointestinal disorders: An open trial of a food elimination diet guided by the ImmunoBloodprint food sensitivity test. Open Journal of Internal Medicine3, 106-113. doi: 10.4236/ojim.2013.33024.