November 15, 2022  |  Luke Lemons 

A bite of cheese here, a chomp of bread there, and next thing you know your stomach has taken a turn for the worse. If you’re one of the many people out there who has noticed that they have stomach issues or other adverse reactions after eating select foods, you may have also wondered, “Do I have a food intolerance or is it something else?” or “Should I do a food sensitivity or food allergy test?” 

While there are plenty of at-home food reaction tests on the market right now, what many people don’t realize is that most of these tests are only for food sensitivity or food intolerance and can’t be used to help to clinically diagnose an allergy.² It’s important to remember, food sensitivity and intolerance tests are not food allergy tests.

You may now be asking, “What’s the difference between a food allergy, food sensitivity, and food intolerance test?”

Food allergy vs. food sensitivity vs. food intolerance

First, it’s important to note that the medical definitions of the words “sensitivity” and “intolerance” are wildly debated in the scientific world and are sometimes loosely applied to food related reactions. At-home food sensitivity tests that you see online, at retailers, or suggested after a Google search take advantage of the vague medical definitions of “sensitivity” and “intolerance” in order to sell tests that can’t even indicate whether you have a food sensitivity.¹ Don’t be fooled into thinking that these tests can confirm a sensitivity, let alone an allergy.

Often, terms “food intolerances” and “food sensitivities” are used interchangeably to mean the same thing. In that way, they are the same, however, their differences are still scientifically debated. Food sensitivities/food intolerances may be due to an enzyme deficiency (like in lactose intolerance) while some sensitivities may be due to a pharmacological reaction (like in caffeine sensitivity).⁴

While sensitivities and intolerances have incoherent definitions, allergies are clearly defined as a reaction that occurs due to your immune system using one very specific type of antibody (more on which one below).^5,6 The presence of this antibody is the limiting factor in identifying whether you have an allergy or not.⁷

The easiest way to divide up the different types of food reactions is to imagine them being a part of one of two buckets: immune system related and non-immune system related.

In food allergy related immune system reactions, the immunoglobulin E (IgE) antibodies in your immune system recognize an otherwise harmless food, like eggs, as a threat. These antibodies go on to trigger your cells into releasing different substances; one of which is a chemical called histamine that causes inflammation and leads to a variety of symptoms like rashes, hives, difficulty breathing, or—worse—anaphylaxis.⁶ IgE is produced by your body when you have an allergy to an organic substance like food or pollen, because of this we can determine if someone might have an allergy by seeing if they have specific IgE for the allergen in question.

If there are no specific IgE antibodies involved and you didn’t have a reaction, then you do not have a clinical allergy.³ This is also true for respiratory allergies. (Check out this article on the difference between a nonallergic vs. allergic reaction for more info on respiratory allergies.)

In non-allergy food related immune system reactions, other antibodies may be involved, however, because IgE is not involved in these reactions they cannot be clinically classified as an allergy.³ These types of reaction may be due to other immune system related diseases, like celiac disease or salmonella poisoning. But again, these aren’t allergies.

In non-immune system related food reactions, the body may not be processing or digesting food appropriately (this isn’t usually dangerous, but it can obviously be uncomfortable).¹⁰ However, scientists still don’t know exactly how certain symptoms arise.⁴ For example, the precise cause of irritable bowel syndrome (IBS) isn’t known,¹¹ but what we do know is that if neither immunoglobulins nor other immune complexities are involved in a reaction, it doesn’t involve your immune system.

How does food sensitivity testing work?

So, what does all this talk about immunoglobulins have to do with food reaction testing? Well, in food sensitivity tests—especially at-home tests—they look at the IgG in your blood. Although these tests may claim to be allergy tests, since they do not test for the presence of IgE antibodies, it means that they are not testing for allergic sensitization. Having high IgG for specific foods is likely a normal immune response when certain foods are eaten, and the American Academy of Allergy, Asthma, Immunology (AAAAI) states that there is no reliable scientific or medical research which says that IgG antibodies can accurately indicate a food sensitivity or a food allergy.¹⁰ It may seem harsh, but because of this, at-home food sensitivity tests are… well, kind of pointless.

Allergy and Immunology experts agree:

• The European Academy of Allergy and Clinical Immunology (EAACI) reports that using food sensitivity tests which examine IgG are considered “irrelevant” for the examination of food allergy or intolerance and “should not be performed in case of food-related complaints.”¹
• The American Academy of Allergy, Asthma & Immunology (AAAAI), the American College of Allergy, Asthma & Immunology (ACAAI), the Joint Council of Allergy, Asthma & Immunology (JCAAI) formed by ACAAI and AAAAI, and the World Allergy Organization (WAO), all state that tests based on IgG antibodies should not be used in the diagnosis of food allergy.²

Having IgG for a certain food simply means that at some point in your life you ingested that food. Whether it was a scoop of ice cream as a child or your first bite of an apple at daycare, your immune system noticed this new foreign substance and created new antibodies for them.⁴ If you have a food sensitivity test that says you have IgG for apples, it simply means that you’ve eaten an apple at least once in your life. Outside of that, it’s debatable whether an elevated IgG food sensitivity test means anything else.

How does food allergy testing work?

Because only IgE antibodies are involved with allergies, the National Health Institute (NIH) suggests that to identify a clinical food allergy, a healthcare professional needs an elevated specific IgE test.³

(Note: for a healthcare provider to diagnose you with a clinical food allergy you also need a history of reacting to that food.)³

Specific IgE allergy blood tests can be used by any healthcare provider that orders blood testing, from pediatricians and primary care clinicians, to allergists and gastroenterologists. If you’re interested in getting a specific IgE blood test, be sure to check out our get tested page.

Which is better: a food allergy test or a food sensitivity test?

In medicine, it’s hard to claim that one test is better than another; however, when using a blood test to help diagnose an allergy, specific IgE is key. Furthermore, specific IgE testing may help to rule out allergy as the cause of any irritating symptoms you experience when you eat a certain food.  

If you start your allergy journey by getting an at-home sensitivity test (IgG), whether it’s elevated or not, you still need to visit your healthcare provider to get tested for food allergies in order to be clinically diagnosed because IgG does not indicate a food allergy.²

Getting results from an at-home IgG sensitivity test is like if a health care provider reviewed your symptoms and said, “You might be sick, idk.” To really understand your illness, your healthcare provider needs to order a more appropriate test, like a specific IgE blood test.

Let’s now say that you decide to start your health journey by getting an allergy blood test (IgE). If it’s elevated and you have a history of reacting when you eat food, you have an allergy.³ If it’s negative, allergies may be ruled out, narrowing down what may be causing your symptoms.

On top of that, while food sensitivity tests may be convenient to get, it’s important to know that these tests offered by companies are not FDA cleared. On the other hand, the allergy blood tests that your clinician can order from laboratories, are medically backed, FDA cleared, accurate, and precise.¹²

So, if you see an IgG food sensitivity test on the shelf of your pharmacy or being advertised to you online, remember, they may not be credible and may not provide any impactful health information.¹⁰

It’s your health, and you deserve the best for you; food sensitivity tests may be a click or scan away, but why sacrifice quality and accuracy? It’s important to be empowered to take charge of your symptoms and seek the best information to help you live a happy and healthy life.