My Experience with LEAP and MRT

When I was first diagnosed with IBS in 2011, the most helpful member of my healthcare team was my nutritionist. She listened when physicians didn’t; she gave me concrete steps to take to feel better. And, she’s a Certified LEAP Therapist (CLT) – someone who’s been trained in the Lifestyle Eating And Performance (LEAP) protocol. This uses the results of a food sensitivity test to design a tailor-made elimination diet.

I was eager to try anything, take any test, to see if we could find a solution for my painful IBS-M.

What is a mediator release test (MRT)?

The test, which is patented by a company called Oxford Biomedical Technologies, is the Mediator Release Test (MRT). MRT is supposed to pinpoint whether certain foods and chemicals cause immune cells to react and release mediators into the blood. Mediators include substances such as histamines, prostaglandins, serotonin and others that are believed to have negative effects on our physiology. The theory is that foods that provoke mediator release in “meaningful amounts” may cause the symptoms experienced by people with so-called “sensitivity-related illnesses” such as migraine, GERD, fibromyalgia – and IBS.1

How does mediator release test work?

The test covers about 120 foods and 25 other chemicals/additives. You provide a blood sample. It’s divided and dispensed into individual test vials, where it’s allowed to “incubate and react” with each test substance. If one of those substances causes a reaction, mediators are released from white blood cells. As a result, there is a shift in the proportion of blood cells versus blood plasma in the sample. The blood cell portion decreases; the plasma portion increases. That is measured to determine the level of reactivity.1

Significant reactions are categorized as “reactive” (red) or “moderately reactive” (yellow). Non-reactive substances are categorized as green and form the basis of the LEAP ImmunoCalm Diet Plan. This is an elimination diet that limits you to 20 to 25 different green foods. Over time, yellow foods and substances may be added as tolerated. By choosing green foods that people like, the thinking is that it’s easier to sustain than a typical rotation diet.1

To be clear, the test doesn’t identify food allergies; just sensitivities or intolerance. Even foods commonly believed to be anti-inflammatory could be reactive for certain people, the company says. They claim to be able to provide relief in a matter of days in people who follow their plan.

Mediator release test are still controversial for IBS

The whole methodology is actually pretty controversial. The Academy of Nutrition and Dietetics has taken a stand against MRT because it lacks what they consider to be reliable scientific evidence. In 2016, they even stopped issuing continuing professional education credit for MRT courses. They stated that credentialed members who use MRT “must weigh the risks and benefits of this strategy, for which there are no evidence-based guidelines.”2

A quick Google search will reveal that many nutritionists see MRT as a big scam – one that can cost patients hundreds of dollars (Health insurance doesn’t usually cover it). Nutritionists worry that LEAP may restrict people from eating foods that are actually harmless, and distract them from uncovering the true cause of food-related symptoms. All while causing needless anxiety. And yet, plenty of nutritionists (plus naturopaths and other alternative providers) still offer MRT, and plenty of patients credit it with incredible symptom turnarounds.

My food sensitivity test results

So, what about this patient? I can’t say that I experienced a miracle, but my test results were interesting.

Shades of red, yellow, and green

Fortunately for me, I had very few red or yellow substances. The ones that did show up could explain some issues I’ve had. Some notable examples:


  • Candida albicans: This is a kind of yeast naturally found in the gut flora, and it’s not usually problematic for healthy people. But it’s implicated in 90% of vaginal yeast infections—something I struggled with for years.
  • Tomatoes: While I love the taste, raw tomatoes do a real number on my stomach if I eat too much. I don’t think this is uncommon, though.
  • Coffee and tea: I’ve never understood the appeal of coffee. Of course, with my tummy troubles, I’ve consumed a boatload of tea in my lifetime. But it’s given me more bellyaches than it’s cured (note: not the case for herbal “teas,” which do help).
  • Lemons: I adore them, but of course the high acidity means consume in moderation.
  • Pistachios: This was a surprise! I honestly don’t know what to make of it. I love those little things and never felt they caused problems.


  • Cow’s milk and yogurt: I’m moderately lactose intolerant, so this wasn’t a shock. Meanwhile, cheddar cheese is Green (I do tolerate harder cheeses fairly well.)
  • Bananas: A-ha! Could this explain my mild aversion to that tubular fruit? They always make me burp.
  • Cucumbers: Different color tube, same burps! (But they have that effect on a lot of people…)
  • Apples: Never craved them like many people do, as I feel they give me – you guessed it – gas (I’ve found Granny Smiths bother me less).
  • Cinnamon: Pity me – I used to make a “healthy” low-fat breakfast smoothie with yogurt, apples and cinnamon. My poor stomach hated it. Now I know why.
  • Turmeric: I’ve taken this as a supplement for its anti-inflammatory effects. I wonder if it even worked?
  • Rice, blueberries, avocados, chicken: Go home, MRT – you’re drunk! I adore these foods and they adore me back.

What is next for my IBS?

My nutritionist noted that just because I don’t develop noticeable symptoms doesn’t mean that there isn’t something happening at a cellular level. That was the point of the test, she explained: I already know what some of my trigger foods are. MRT could help me identify additional foods that might cause problems.

Based on my test results, she developed a 4-week ImmunoCalm Diet for me. But I declined to follow it. I had very few red and yellow foods and I naturally avoid most of my them anyway. So, I didn’t see much point in getting protein, for example, from chickpeas, soybeans, and clams (and NOTHING ELSE) in Week 1, just to work my way towards chicken!

In sum, MRT didn’t do a lot for me in terms of controlling my IBS. But neither was it a complete waste of time or money. For example, it could explain why common remedies like the BRAT diet (Bananas, Rice, Applesauce, Tea) never seems to quell my diarrhea. Or why iced tea on an empty stomach can make me double over in pain.

As people with IBS, knowledge is our best friend, and I’ll take more insights over fewer insights any day.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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