Food Intolerance Testing — Alcat & IgG — myth or science?

The words ‘Food Intolerance’ are pretty common today with the rise of popular diets promoting the elimination of foods like wheat, dairy, soy, etc. You hear bloggers and celebrities say they’ve eliminated wheat (or insert any other food) and it’s cured their stomach problems, eczema, migraines, or their child’s autism. Anyone dealing with a chronic health issue would love to quickly and easily figure out exactly which foods are causing their health problems (who wouldn’t?!).

So this leads us to food intolerance testing – what it is, what it involves, and whether the tests really work. The two types of tests that I hear mentioned most often are the IgG test and the Alcat Test.

Before delving into those two tests, let me take a quick detour and talk about the difference between a food allergy and a food intolerance (it’s gonna get a little sciency, but keep with me!)

A food allergy involves the immune system making IgE antibodies and can be life-threatening.  People with food allergies cannot eat even a microscopic amount of the food they’re allergic to. Examples of food allergies are peanut, tree nut, and milk allergies, among others.1

A food intolerance, on the other hand, involves the digestive system. In this case, the gut cannot completely break down the offending food. Unlike an allergy, people with a food intolerance can generally eat a small amount of the food without problems. A common example is lactose intolerance.1

As an important note, both of the tests we’re about to look at are testing for intolerances, not allergies!

Back to the intolerance tests. Let’s start with Alcat.

I first remember hearing about Alcat 4 years ago when both my mom and a friend told me about the test. My mom told me a friend of hers swore by it and that it had changed her life. My friend said the same thing. Seemed promising, right? So I looked into it.

A quick google search landed me on the Cell Science Systems website. The company says the Alcat Test may help determine which foods cause chronic inflammation in the body leading to GI and metabolic health issues. The process involves sending a sample of your blood to Cell Science System’s laboratory. There, your white blood cells are tested against 450+ foods and other substances to see which ones cause food sensitivities. They claim that an increase in the number and size of white blood cells, when exposed to a certain food, indicates an intolerance to that food. The company then sends you a test report, a list of foods to avoid, and a shopping guide.Easy and straightforward, right?

Now for the IgG antibody tests.

How is this test different than Alcat? Like Alcat, your blood is tested against various foods to determine reactivity. However, unlike Alcat, IgG tests measure the levels of IgG antibodies produced in response to a food. The companies that provide this type of testing say that the higher the IgG response, the higher the body’s reactivity to that food. One Texas-based company, EverlyWell, tests 96 foods, including gluten, wheat, dairy, and yeast, to help people get rid of acne, eczema, food intolerance, fatigue, IBS, migraines, and respiratory issues.3

It seems like both tests offer some pretty amazing results!

But what do the experts say about the accuracy of these tests?

Let me first say that food allergies are very well defined, and there are very specific guidelines provided by numerous reputable organizations.4,5,6 Food intolerances, on the other hand, are not as well defined and do not have such specific guidelines for treatment and management.

However, Food Allergy Research and Education provides a list of unproven diagnostic tests for food allergies, and the IgG test and cytotoxicity test (Alcat) are two of them. Even though we’ve already established that both IgG and Alcat do not test for allergies, here is what this organization says about IgG tests:

“IgG antibodies are found in both allergic and non-allergic people. IgG are the normal antibodies made by the body to fight off infections. The creation of IgG antibodies is thought to be a normal response to eating food. For example, IgG antibodies actually go up during successful research studies on food  immunotherapy.”4

 Here is their comment on cytotoxicity tests (Alcat):

“Changes to the appearance of cells upon exposure to allergens cannot be viewed with a microscope. Those changes can only be seen through a much more advanced technique that is only available in research labs.  So, the changes reported in this test are either not real or not related.”4

The American Academy of Allergy, Asthma & Immunology (AAAAI) on IgG tests:

“The detection of food-specific antibody in patient sera [blood] does not necessarily indicate food allergy or intolerance, but rather a physiologic response of the immune system to exposure to food. For IgG and more specifically IgG4, this may be the normal human response.”5


“Some practitioners order IgG and IgG4 antibody tests for foods, and the results may be misinterpreted leading to diets that may be nutritionally inadequate and are certainly not easy for patients to follow.”5

The Canadian Society of Allergy and Clinical Immunology (CSACI) advises against IgG testing:

“There is no body of research that supports the use of this test to diagnose adverse reactions to food or to predict future adverse reactions. The literature currently suggests that the presence of specific IgG to food is a marker of exposure and tolerance to food….Hence, positive test results for food-specific IgG are to be expected in normal, healthy adults and children. Furthermore, the inappropriate use of this test only increases the likelihood of false diagnoses being made, resulting in unnecessary dietary restrictions and decreased quality of life.”6

Blue Cross Blue Shield also weighs in on the Alcat Test:7

“ALCAT is a laboratory-developed test that is not subject to U.S. Food and Drug Administration approval.”

“There is a lack of published research on the diagnostic accuracy of the test; therefore it is not possible to determine the sensitivity, specificity, and/or predictive value of the test.”

“Guidelines for the diagnosis of food allergy from the National Institute of Allergy and Infectious Disease do not discuss use of ALCAT. Due to the limitations of the evidence base, and lack of acceptance of the test as a component of standard care by experts in this area, ALCAT is considered not medically necessary.”

Aetna also considers Alcat an experimental test and not proven to be effective:

“ALCAT food allergy testing utilizes an indirect method of measuring mediator releases and the effects of other pathogenic mechanisms of allergy and delayed hypersensitivity…  This automated testing has not been validated.”8

What’s the bottom line?

While Alcat and IgG claim to offer some pretty amazing results, these tests have not been proven effective in determining food intolerances. They are not regulated tests and can result in false diagnoses. Equally important, they can lead people to unnecessarily restrict food choices. Finally, neither test is covered by insurance, which means the out-of-pocket cost is $199 for EverlyWell’s IgG test and anywhere from $200-$800 for Alcat’s food intolerance tests.

Instead of using IgG or Alcat, talk with an allergist, primary care physician, gastroenterologist, or registered dietitian nutritionist (RDN) about your concerns if you suspect you have a food intolerance!


  1. Food allergy versus food intolerance. American Academy of Allergy, Asthma, and Immunology website. Accessed April 22, 2017.
  2. Alcat Test. Cell Science Systems website. Accessed April 22, 2017.
  3. Food Sensitivity Test. EverlyWell website. Accessed April 22, 2017.
  4. Unproven Diagnostic Tests. Food Allergy Research and Education website. Accessed April 22, 2017.
  5. Bock SA. AAAAI support of the EAACI Position Paper on IgG4. J Allergy Clin Immunol. 2010; 125(6):1410.
  6. Carr S, Chan E, Lavine E, Moote W. CSACI Position statement on the testing of food-specific IgG. Allergy Asthma Clin Immunol. 2012; 8(1):12.
  7. Antigen Leukocyte Antibody Test. Blue Cross of Idaho website. Accessed April 22, 2017.
  8. Allergy and Hypersensitivity. Aetna website. Accessed April 22, 2017.

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