IgG Food Tests: Understanding Food Sensitivities
Written By: Jordan Stachel
There are several different kinds of tests available for food allergies and sensitivities. However, not all are created equal. Immunoglobulin G (IgG) tests are a commonly used option that can be helpful for ruling out any food sensitivities. Read this article for everything you need to know.
What Are IgG Food Tests?
IgG food tests are typically used to test people for food allergies or sensitivities, although they are used more commonly to screen for sensitivities. Immunoglobulin G (IgG) specific antibodies are important for fighting off infections and make up the majority of the antibodies found in blood.[1] Another type of test that screens for Immunoglobulin E (IgE) antibodies is more commonly used to screen for food allergies.[2]
If you have a food sensitivity and are experiencing symptoms of gastrointestinal discomfort after eating certain foods (i.e. gas, bloating, general stomach pain), your body is likely also making increased levels of IgG antibodies each time you eat those foods. Because food sensitivities mainly affect the gastrointestinal tract, there may be increased levels of IgG antibodies caused by increased gut permeability after consuming certain foods. In a healthy gastrointestinal tract, there will always be some permeability that allows nutrients to pass through. However, if permeability increases too much, this can pose problems like leaky gut syndrome, in which individuals do not have adequate nutrient absorption.
How Do IgG Food Tests Work?
To test for food sensitivities using an IgG test, typically a blood sample is drawn and analyzed.[2] The higher the levels of IgG after exposure to certain foods, the greater the degree of food sensitivity present for that individual. While IgG food tests are not always conclusive in figuring out if a person is definitively suffering from food sensitivities, they can be a helpful tool in the toolbox for more clarity.
Once you receive the results of a food sensitivity test, it is best to work with a team of qualified professionals to take the next steps. These steps may include follow-up testing, elimination diets, and/or a combination of both.
How Accurate Are IgG Food Tests?
There is mixed information and research surrounding IgG tests and their accuracy. In general, it is likely a good idea to use IgG tests more as a tool for gathering information and less as a diagnostic tool. This allows you to get increased clarity and information regarding food sensitivities in general, but it is not recommended to use them to indicate a surefire food-related diagnosis.
Some people believe that IgG food tests should not be used as diagnostic tools due to sensitivity reactions that occur in people normally when eating certain foods. There is a normal reaction to food antigens that causes people to sometimes produce higher circulating levels of IgG.[3] In normal, healthy individuals, these IgG levels will be cleared over time and not cause any issues. However, if these levels are measured via a blood test, they may show up as elevated, raising concern that an individual may be sensitive to a food that should not pose any issues. If you are not experiencing symptoms after eating certain foods, it is not likely that you will need to omit these foods from your diet.
Overall, IgG tests should not be used to diagnose food allergies or sensitivities.[4] To diagnose food allergies, more information and different kinds of testing are needed. It is also important to not make extreme dietary changes to your diet after obtaining results from an IgG test without the support of a dietitian or qualified healthcare provider.
Removing many foods from the diet without supervision puts an individual at risk for unnecessary restriction and potentially a decline in nutritive intake.[4] In addition, not all IgG tests are created equal, and it is important for you to choose options that are safe and well-vetted to ensure that you are getting reasonable results.
What Do IgG Food Tests Look For?
IgG tests are done via blood and can test for different foods. Typically, high-allergen foods are included in most IgG tests, which can include egg, shellfish, dairy, corn, tomato, mushroom, soy, wheat, pork, chicken, and beef.[5]
Everlywell offers two different IgG test options that test you for 96 different foods in the Food Sensitivity Test, or 204 different foods in the Food Sensitivity Comprehensive Test. In the Food Sensitivity Test, you are tested for several foods within the categories of dairy, eggs, fruits, grains, legumes, meat, seafood, seeds, nuts, vegetables, and spices. The Comprehensive Test screens for the same categories but includes more food options within each category. If you are looking for a jumping-off point in getting some answers to if you may have sensitivity to a wide array of foods, Everlywell’s food sensitivity tests are an excellent starting point.
IgG vs IgE Test
IgG tests can be used to screen for food sensitivities, rather than allergies, as IgG is antigen-binding but does not activate a histamine response in the body.[6] IgG antibodies are also involved in immune functioning.
IgE antibodies are made by the B cells in the body and are found in the blood in lesser concentrations than IgG. IgE cells are also antigen-binding, but they bind specifically to the surface of basophils or mast cells. When this process happens, it evokes an immune response in the body due to the release of chemicals like histamines. These types of chemicals are involved in allergic reactions. This is why IgE testing is considered to be more indicative of food allergies when compared to IgG testing.[6]
Different types of IgE tests can be conducted to screen for allergies. One is a total IgE test, which measures the total amount of IgE in the blood. The other is the specific IgE test, which measures the IgE in the blood due to exposure to specific allergens.[7] If you or someone you know thinks that they may have food allergies, IgE testing is considered to be a good test to confirm this. With food allergies, the immune system mistakenly thinks that the foods you are eating are harmful to the body and begins to attack them, raising IgE levels. Having allergen-specific IgE testing done can be helpful to determine if you are allergic to a specific food or foods.[7]
Take the Guesswork Out of Food Consumption With Everlywell
If you are suffering from food allergies or sensitivities and are experiencing uncomfortable symptoms, it can often feel like a confusing and discouraging journey. The good news is that with high-quality testing and support from qualified healthcare providers, this is not a journey that you have to embark on alone. While food sensitivity testing may not work as a diagnostic tool, it can begin to point you in the right direction of some foods to which you might have sensitivities. With allergies, testing results are often more clear and conclusive. Take the first step today towards ending the guesswork with Everlywell.
References
- Immunoglobulins blood test. Last Reviewed September 12, 2022. Accessed November 6, 2024. Medical Citation URL.
- Shakoor Z, Faifi AA, Amro BA, Tawil LNA, Ohaly RYA. Prevalence of IgG-mediated food intolerance among patients with allergic symptoms. Annals of Saudi Medicine. 2016;36(6):386-390. doi:10.5144/0256-4947.2016.386. Accessed November 6, 2024. Medical Citation URL.
- Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Advances in Dermatology and Allergology. 2016;4:253-256. doi:10.5114/ada.2016.61600. Accessed November 6, 2024. Medical Citation URL.
- Bock SA. AAAAI support of the EAACI Position Paper on IgG4. Journal of Allergy and Clinical Immunology. 2010;125(6):1410. doi:10.1016/j.jaci.2010.03.013. Accessed November 6, 2024. Medical Citation URL.
- Wu M, Wang X, Sun L, Chen Z. Associations between food-specific IgG and health outcomes in an asymptomatic physical examination cohort. Nutrition & Metabolism. 2022;19(1). doi:10.1186/s12986-022-00657-5. Accessed November 6, 2024. Medical Citation URL.
- Perdue SS, Humphrey JH. Immune system | Description, Function, & Facts. Encyclopedia Britannica. Published October 17, 2024. Accessed November 6, 2024.
- Philadelphia CHO. Allergen specific IGE test. Children’s Hospital of Philadelphia. Last Reviewed 2024. Accessed November 6, 2024.