• Marissa Mekelburg Functional Medicine Dietitian

Is the LEAP food sensitivity test the best? Yes!

Are you ready to stop guessing – and start testing – so that you can finally get to the bottom of your lurking symptoms? While there are many food sensitivity tests available today, there is one gold-standard test that I recommend for my clients: the MRT food sensitivity test. Why? It is the best!


FYI, sometimes the MRT food sensitivity test is often mislabeled as the “LEAP food sensitivity test” but the LEAP part is actually the dietary protocol to go along with the test.


In this blog post, I’ll explain what the different options are for food sensitivity testing and why MRT testing and the accompanying LEAP protocol is the absolute best, most accurate way to know what is going on with your body.


And with the data that these food sensitivity tests provide, you start to resolve your symptoms ASAP.



 pipette filling glass tubes for testing

Photo by Louis Reed on Unsplash



If you’re new here, welcome! I’m Marissa, Registered Dietitian Nutritionist, Functional Nutrition Practitioner, Certified LEAP Therapist, and Digestive Health Expert. I am the founder of Wholistic Works, an online nutrition clinic based in Colorado where I help clients resolve their digestive symptoms, once and for all.


Let’s start this post with a quick discussion of the different kinds of reactions that your body can have to food. Understanding the difference between these three reactions will help you to better understand which food sensitivity test is best for you (and why!).



What are allergies, sensitivities, and intolerances?


Unfortunately, your body can have an overreaction to food through a couple of different methods. It is possible to have allergies, sensitivities, and intolerances to food. They’re unique in terms of what is going on with your body and your immune system. Understanding these differences helps you to understand which test will provide you with the information you need to resolve your symptoms.


Let’s start by exploring what a food allergy is.



What are food allergies?


A food allergy is what you might think of with a kiddo who has an allergy to peanuts. If they accidentally eat something with peanuts, their reaction might be incredibly quick and incredibly dangerous; difficulty breathing, hives, itching and swelling on the face, mouth, and tongue, dizziness and abdominal pain, vomiting, and diarrhea. Treatment might involve an EpiPen and an ER visit.


During an allergic reaction, your immune system releases special proteins called IgE antibodies (1). They’re sounding the alarm that there is “danger”. This process causes your body to release defense chemicals that cause your rapid and severe symptoms.


If you get blood testing with an allergist, they’re measuring IgE activity in the blood (2).


The top 8 Food Allergens are (3):

1. Peanuts

2. Shellfish (such as crab, lobster, or shrimp)

3. Fish (such as bass, flounder, and cod)

4. Eggs

5. Tree nuts (such as almonds, cashews, and walnuts)

6. Cow’s milk

7. Soy

8. Wheat


An allergic reaction is different from a food intolerance. Let’s compare that to an allergy, now.



Food intolerance


Interestingly, an intolerance does not involve the immune system at all. Food intolerances are much more common than allergies or sensitivities and may occur when for example, the body lacks the correct enzyme to break down a food component.

An example of this would be lactose intolerance, which is very common and is caused by the body’s reduced or absent production of the enzyme lactase which is what breaks down the sugar in milk called lactose.


When there isn’t enough lactase, lactose remains undigested and passes into the large intestine which creates an osmotic effect increasing fluid into the large bowel, resulting in pain, gas, and diarrhea.


Or, an intolerance can happen if your body is mal-absorbing a food component, such as fructose. Fructose intolerance is less common . A person can also be histamine intolerant or amine intolerant


Lastly, a food intolerance can also be the result of a gut infection – like SIBO – causing a FODMAP intolerance.


In the case of food intolerances, there are no immune messengers being sent around the body so a food sensitivity test would not be helpful to offer a diagnosis.


Food intolerances are treated by avoiding the food that you have trouble digesting, taking digestive enzymes with meals, or consuming products that already contain the necessary enzymes.


And last but not least: what is a food sensitivity? A different reaction than an allergy or an intolerance.



Food sensitivity


A food sensitivity is a less severe reaction to a food that may take hours or even days to manifest.


Food sensitivities do involve the immune system, but they do NOT involve IgE antibodies.


Unlike allergies, sensitivity reactions are often delayed by up to 72 hours after ingestion. This delay makes food sensitivities much more difficult to diagnose…can you remember every single thing you ate in the past three days? Nope? Me neither! Food recalls might help to identify patterns, but they’re much more prone to human error.


There are two different types of sensitivity reactions that can occur:

Type 2 hypersensitivity is a reaction that occurs when the body makes IgG and/or IgM antibodies in response to a perceived threat (4). Although their names are similar, they are different from the IgE involved with true allergies.


These IgG or IgM antibodies attach to offending food antigens in the bloodstream and form immune complexes, kind of like putting a nametag on. Once these immune complexes reach and attach to tissue, your immune system gets signaled that an “invader” is present. White blood cells are summoned to the area and release “chemical mediators” in an attempt to destroy the immune complex that is deemed to be harmful and unwelcome. This is like spraying bear spray if a brown bear gets too close.


But, the mediators aren’t without fallout. The mediators can cause inflammation and damage in the tissue, just like it would hurt if you got bear spray in your eyes (5). It is the mediators that lead to symptoms, not the food itself.

Type 4 Hypersensitivity doesn’t involve any antibodies. Instead, they involve a different member of the immune system called T-cells.


T-cells decide that the food antigen is a threat. Again, white blood cells are called to the scene and release the same mediators that we talked about with the type 3 reaction. And the results are the same; inflammation, pain, and other symptoms. Ouch!


For more information about these three reactions, check out this post: Food allergies, food intolerance, and food sensitivities...what's the difference?



Quick recap


That was a lot of scientific info, right?


To summarize - your body can have an overreaction to foods through different immune pathways. Depending on which pathway your body will send different messengers; just like we can send information via snail mail, email, text, or instant messenger.


● In food allergies, your body is sending IgE antibodies.

● In food sensitivities, your body could be sending IgG or IgM antibodies or T-cells

● And in food intolerances, there are no antibodies.


So, to accurately test what is going on, you have to have the right test to be able to accurately measure the messengers and mediators.




a woman in a white lab coat dropping purple liquid into small white pipettes

Photo by Julia Koblitz on Unsplash



Risk factors for food sensitivities


Who can develop food sensitivities? Many of us, unfortunately. Our modern lifestyle is pretty challenging to our gut health, and if our gut health is compromised, we are at greater risk for many other conditions, including food sensitivities.


Your risk goes up if you have any gut infections like SIBO or parasites. Or, if you’ve had a foodborne illness or any other disease that damages the intestine such as celiac. You can also develop a sensitivity due to molecular mimicry; if your body thinks that another food looks like a food you’re already sensitive to, you can start having issues with that food as well.


Quick recap? Basically, anything that can damage the lining of the intestine and increase permeability can lead to developing sensitivities. Gut health is so important!



Symptoms of food sensitivity


What does a food sensitivity feel like? Symptoms vary greatly, but may include:


● Bloating/gas

● Migraine/headache

● Brain fog

● Diarrhea

● Constipation

● Skin issues like rosacea or eczema

● Insomnia

● Fatigue

● Sinus issues

● And more!


There are also differences in how strong the reactions are. Some people have a reaction to a large serving of a food but are able to tolerate a small amount; this is different from an allergic reaction where a tiny bit of food may cause a severe, life-threatening reaction.


Why is the MRT/LEAP food sensitivity testing the best?

As we learned earlier in this post, food sensitivities are not mediated by IgE antibodies and mast cells. And so, traditional allergy testing, which is measuring IgE activity, will not identify them.


However, there are several food sensitivity tests on the market. What makes MRT testing different?

The most accurate way to identify food sensitivities currently is with the Mediator Release Test (MRT for short). This blood test measures your body’s inflammatory response to 170 foods and chemicals, no matter what pathway triggered them (IgG, IgM, T-cells, etc.) (6).


This test is measuring the release of cytokines, histamine, leukotrienes, prostaglandins, etc., from neutrophils, monocytes, eosinophils, and lymphocytes that lead to all the negative clinical effects that you are enduring; these are the causes of your symptoms!

Other food sensitivity tests are far less comprehensive…and far less accurate.


Most of them are only testing for IgG antibodies, which can be elevated just due to exposure to that food. This is important to understand: just because the IgG antibody is present does not mean that the body is creating an inflammatory response to that food.


This is the main difference between the MRT test and other options on the market…and it’s why I like the MRT test the best. MRT is actually measuring the inflammatory response to a food, not just that your body can identify a food.


Additionally, MRT is still the ONLY test available that tests for food chemicals. This includes both naturally occurring chemicals like solanine and man-made chemicals, like artificial colors.


Getting these results is actually just the beginning of your healing journey…receiving your results can feel pretty darn overwhelming. You have discovered the many foods that your body is not tolerating well…now what?



How an RD can help


Food is complicated.


And our reactions to foods can be complicated, delayed, and difficult to understand.


I recommend working with a registered dietitian, specifically one that is a Certified LEAP Therapist (CLT). My CLT training goes above and beyond the baseline training that dietitians receive in college. We have additional training in inflammation, the immune system, and food. We have also been trained on how to guide clients through the LEAP dietary protocol that utilizes the results from MRT.

Most other practitioners will only tell clients to avoid reactive foods. In my experience, this is not enough for a person to actually feel better because there are usually many foods that a person is responding to. This means that inflammation is still occurring…and the person is still feeling crummy.

An elimination diet is still considered the “gold standard” when it comes to food sensitivities, but it is far from precise. They’re also pretty difficult to follow. Plus, sensitivities are delayed many times by 72 hours so even with food logs, it can be really difficult to pinpoint the offending food.


MRT lets us see exactly which foods cause inflammation and the accompanying symptoms. Then, when we use LEAP therapy and use MRT to guide the elimination diet, we have much better results.


With MRT testing, I am able to progress my clients through the elimination diet MUCH faster. Many times, people will be on an elimination diet for 3 months or more because they can’t tell what is causing the problem and so they just keep pulling this food or that food and eventually have 6-10 foods they are consuming and still don’t feel well. This can be really frustrating and demoralizing - I want you to feel better far sooner.



What to expect


As a CLT registered dietitian, I use MRT testing and the LEAP protocol to precisely identify and treat my client’s food sensitivities.


With these tools, I am able to guide my clients to feel better more quickly and with less confusion. We get to reintroduce eliminated foods back into their diets more quickly.


But, it is important to know that, even with the best test, this work is not overnight.


Food sensitivities develop because of issues in your gut health. Healing the gut takes time and work. Here is a bit more info about what your journey might look like and how long it will take: How Long Does It Take to Heal Leaky Gut?



Key takeaways


If you want the best answers, you need to use the right test…and partner with the right guide.


Our modern lifestyle is pretty challenging for our gut health. Food sensitivities, and their myriad of symptoms, are becoming more and more common. They’re not the same as allergies, and so an allergy test will not help you to get to the bottom of things. The right test for food sensitivities is the MRT test.


The MRT food sensitivity test will help you to make sense of how your body is responding to almost 200 different foods and chemicals. As a functional nutrition practitioner, I can help you understand the root causes of your symptoms. With your personalized plan, you’ll feel better far more quickly.


If you're ready to get to the bottom of your symptoms, set up an appointment. Together, we’ll discover which foods are causing your symptoms and optimize your gut health so that you’re feeling better more quickly and with less frustration.

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