May 31, 2022

How do food sensitivity tests work? Answering your questions about food sensitivity tests vs elimination diets.


Dr. Carolina Arreola

At-home food sensitivity tests like Everlywell or DNAFit are popular—who doesn’t want to know what foods work and don’t work in their system? However, these tests aren’t as effective or accurate as you’d hope. Whole30 co-founder Melissa Urban caught up with her friend Dr. Caroline Arreola, a licensed Naturopathic Doctor based in California, to talk about the good, the bad, and the alternatives to at-home food sensitivity testing.

Melissa Urban: Now that these tests are more available than ever, what do we need to understand about them?

Dr. Arreola: Food sensitivity tests are certainly popular right now—I am asked about them often in my practice. Before I dive into how these tests work, I think it’s helpful to define a food allergy vs a food sensitivity.

A food allergy is when your immune system identifies a particular food as an invader and then responds to that food by producing allergic (IgE) antibodies. These IgE antibodies bind to mast cells, triggering the release of histamines and an immediate production of symptoms. These symptoms usually include hives, swelling, itching, and difficulty breathing, which can be fatal in extreme cases.

A food sensitivity is when your immune system responds in a similar way but produces different antibodies (IgG) that can cause a much more delayed response. IgG antibodies function differently than IgE antibodies because they do not trigger the histamine release that causes that immediate allergic reaction. Instead, IgG antibodies can mediate inflammatory responses through a variety of different pathways. Due to this response, symptoms of a sensitivity can show up hours to days later, are much more varied, and can include anything from digestive issues and chronic headaches to fatigue, anxiety, or skin issues. Because of the delayed onset, food sensitivities can often go “under the radar” since the link between the food trigger and the symptom it produces isn’t always clear. Generally speaking, food sensitivities are more common than food allergies.

Food sensitivity tests work by testing your blood for the production of IgG antibodies in response to different foods (typically about 96 different foods are tested), and then rating the responses on a scale. This provides the patient with data on what foods, if any, are causing an immune response in their body.

These at-home tests are convenient because you are able to do everything from the comfort of your home. The lab companies provide you with all the instructions and tools needed to collect a small blood sample as well as a prepaid return mailing envelope to send your results back in. Another perk is that it is quick and easy and typically requires little time or commitment on the patient’s end.

MU: They sound amazing—but are food sensitivity tests (which typically cost between $100 and $200) worth the money?

Dr. Arreola: The short answer is no, they’re not always worth the money. Doing a test like this can provide you with valuable information, but they are not perfect and often provide inaccurate results. More importantly, although they do sometimes provide accurate results on which foods can initiate an IgG immune response, they do not address how exactly these reactions can manifest in a patient’s body and what symptoms they are tied to.

MU: What are some of the issues surrounding these kinds of tests? Can they give you false results? Can they tell you which foods are contributing to your energy level fluctuations, digestive distress, joint pain or swelling, skin disruptions, or mental health issues?

Dr. Arreola: A common issue with these tests is that they often give false negatives—meaning they don’t show any reaction when there actually is one. I have had many patients who had clear food sensitivities, most of which they had identified on their own, complete an at-home food sensitivity test and receive results that reported they had no sensitivities. This is common because many people will be sensitive to a food but not sensitive “enough” to trigger an immune response that would be detectable on a blood test.

False positives are also a common issue with these tests. People will receive results that state they produced an immune reaction to nearly every food listed. From my experience, this commonly occurs in cases of intestinal permeability (aka Leaky Gut). Because the barrier of the digestive lining has been compromised, food particles, bacteria, and other toxins are able to gain access to the bloodstream when they normally shouldn’t be able to. When this happens, almost anything you eat can trigger an immune response, but it does not mean that you have a true sensitivity to all those foods. Getting results like this is extremely frustrating for patients because instead of helping them narrow down the cause of their symptoms, they are left feeling even more confused and unsure of how to proceed.

Another issue surrounding tests like this is the misleading concept that you just need to take the test and you’ll magically understand the cause of your symptoms. Food sensitivity tests only show if there is an IgG response to a particular food, but they do not address how exactly these reactions are manifesting in the patient’s body and what symptoms they are tied to. So if someone with chronic joint pain or bloating does a test like this and 4-5 foods come back flagged, they still do not know which food is the culprit of which symptom or if they are related at all.

Because of this, many food sensitivity tests include a two-part elimination and reintroduction diet to supplement the test results. However, I would argue that this elimination and reintroduction phase is the most valuable part of this whole experience and could be done on its own for free, thus making the blood testing portion unnecessary.

MU: So you’re saying a 30-day elimination program like the Whole30 could accomplish the same goalidentifying individual food sensitivitiesin a more effective (or at least equally effective) way?

Dr. Arreola: I 100% would, and often do, recommend doing the Whole30 or some form of a structured elimination diet over using at-home testing kits, absolutely. The Whole30 program eliminates some of the most common food triggers that have often gone undetected, and then provides a structured reintroduction phase to determine the effects on the body. I discussed earlier how if a person does not have a strong enough reaction to a food to elicit an immune response, then they increase the risk of receiving inaccurate results such as a false negative. The beauty of doing an elimination diet such as the Whole30 is that there are no false negatives. Your body doesn’t lie to you, and this program reinforces the fact that you are the only one who can determine if a food makes you feel good or bad.

A proper elimination and reintroduction diet provides you with all the information you need without the cost of a food sensitivity test or the risk of being provided with inaccurate results. Plus, there is so much support that comes along with doing a program such as the Whole30! There are tons of social media channels, meal planning services, websites packed with recipes, YouTube videos, and more, all dedicated to supporting you, helping you interpret your Whole30 results, and providing you with a plan for life after the program. I’d say that is invaluable.

MU: Thank you to Dr. Arreola for helping me explore this trending topic. Here are three key takeaways:

  1. Food sensitivity tests often come with false negatives and false positives, and don’t offer enough context with which to view, interpret, or apply the results to mitigate the negative symptoms you’re experiencing.
  2. Most food sensitivity tests also “prescribe” an elimination and reintroduction program, which is the most valuable part of the entire process, and can be done for free!
  3. Programs like the Whole30 not only offer a structured and proven approach to identifying food sensitivities, but a robust support system for completing the program and integrating your learnings to truly improve your quality of life.

For more on how the Whole30 program works (and how it’s changed millions of people’s lives since 2009), visit the Whole30 YouTube channel and our program resources.

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