What Is MRT Food Sensitivity Testing?
An Evidence-Based Guide
Last Updated: March 11, 2026 | Clinically Informed by Megan Pennington, BSc (McGill), CLT
If you're dealing with chronic symptoms like digestive issues, skin problems, migraines, joint pain, or fatigue that haven't responded to conventional treatment, food sensitivities may be a hidden trigger. But identifying which foods are causing your symptoms can feel impossible—especially when standard allergy tests come back negative and elimination diets leave you frustrated.
This is where Mediator Release Testing (MRT) comes in.
MRT is a blood-based food sensitivity test that measures your body's inflammatory response to 176 foods and chemicals. Unlike traditional allergy tests that only detect immediate IgE reactions, MRT identifies delayed inflammatory responses—the type most commonly associated with chronic conditions.
In this guide, we'll explain exactly what MRT testing is, how it works, its accuracy based on clinical research, and whether it might be right for identifying your food triggers.
The Difference
Food Sensitivity vs Food Allergies: What's the Difference?
Food Allergies (Immediate Reactions)
True food allergies involve IgE antibodies and produce immediate, often severe reactions within minutes to 2 hours. Think peanut allergies, shellfish allergies—reactions that include hives, swelling, difficulty breathing, or anaphylaxis. These are obvious and dangerous. If you have a true IgE allergy, you already know it.
Food Sensitivities (Delayed Reactions)
Food sensitivities involve different immune mechanisms: delayed hypersensitivity reactions mediated by inflammatory cells rather than IgE antibodies. These reactions are:
- Delayed: Symptoms appear 2 hours to 3 days after eating the trigger food
- Dose-dependent: Small amounts may cause no symptoms; larger or repeated exposures trigger reactions
- Cumulative: Eating multiple trigger foods simultaneously can intensify symptoms
- Varied: Can affect digestion, skin, joints, energy, mood, and more
The problem: This delayed nature makes food sensitivities extremely difficult to identify through observation alone. By the time symptoms appear, you've eaten multiple meals and can't pinpoint which food was responsible.
The Science
What Is MRT (Mediator Release Testing)?
Mediator Release Testing (MRT) is a patented blood test that measures your body's inflammatory response to 176 foods and food chemicals. Rather than measuring antibodies (like IgG or IgE tests), MRT measures the end result of inflammatory reactions: the release of inflammatory mediators from white blood cells.
What Makes MRT Different
Measures the Endpoint of Inflammation
Instead of measuring just one pathway, MRT measures the combined effect of all inflammatory pathways by quantifying the release of inflammatory mediators such as histamine, prostaglandins, cytokines, and other chemical messengers.
Quantifies Reaction Severity
MRT categorizes foods by severity of reaction:
- Reactive (Red): Foods causing significant inflammatory mediator release
- Moderately Reactive (Yellow): Foods causing moderate inflammatory response
- Non-Reactive (Green): Foods causing minimal or no inflammatory response
Tests Foods AND Chemicals
MRT is the only food sensitivity test that includes food chemicals and additives in addition to whole foods—testing for reactions to preservatives, food dyes, natural chemicals like salicylates, and more. Many people react to chemicals rather than foods themselves, which often goes undetected with food-only testing.
Validated clinical outcomes in identifying inflammatory food reactions
The Process
How MRT Testing Works
When you eat a food to which your immune system is reactive, white blood cells recognize components of that food as threatening and release inflammatory mediators—chemical messengers that trigger inflammation throughout your body. This inflammation manifests as the symptoms you experience.
Traditional antibody testing only measures one aspect of this process. MRT measures the actual inflammatory response—which directly correlates with symptom production.
The Laboratory Process
- Your blood sample is divided into small portions
- Each portion is exposed to a different food or chemical extract (176 substances tested)
- Food and chemical antigens cause mediator release from white blood cells
- A specialized impedance flow cytometry technique measures changes in the blood sample
- The degree of change is quantified, producing a numerical score representing mediator release (reaction severity)
- Each tested substance is categorized as non-reactive (green), moderately reactive (yellow), or reactive (red)
Clinical Validation
MRT Accuracy: What the Research Shows
MRT's accuracy has been evaluated using gold-standard double-blind, placebo-controlled food challenges. The published data shows:
MRT correctly identifies 94.5% of foods that cause reactions
MRT correctly identifies 91.7% of foods that do NOT cause reactions
These numbers place MRT among the most accurate food sensitivity tests available—significantly outperforming IgG antibody testing, which shows poor correlation with clinical food challenges in most studies.
98% of our patients experience significant symptom improvement within the first month of following their personalized MRT-guided protocol.
References:
1. Immunology and Microbiology,Mediator Release Science Direct
2. Clinical validation studies available at nowleap.com/research
3. Additional reference studies available at meganpennington.com/research
How It Compares
MRT vs Other Food Sensitivity Tests
| Testing Method | What It Measures | Accuracy | Best For |
|---|---|---|---|
| MRT | Inflammatory mediator release | 94.5% sensitivity, 91.7% specificity | Food sensitivities & chemical reactions |
| IgG Testing | IgG antibodies to foods | Poor correlation with symptoms | Not recommended by allergists |
| IgE Testing | IgE antibodies (true allergies) | High for immediate allergies | True food allergies only |
| Elimination Diet | Patient symptoms during challenge | Effective if done correctly | Limited suspected triggers |
Ideal Candidates
Who Should Consider MRT Testing?
Digestive Issues
- Irritable Bowel Syndrome (IBS)
- Inflammatory Bowel Disease
- Chronic bloating, gas, diarrhea
- Undiagnosed digestive distress
Autoimmune Conditions
- Hashimoto's thyroiditis
- Rheumatoid arthritis
- Lupus, MS, Psoriatic arthritis
- Any autoimmune disease
Chronic Skin Conditions
- Eczema and atopic dermatitis
- Psoriasis
- Chronic hives
- Treatment-resistant acne
Chronic Pain & Fatigue
- Fibromyalgia
- Chronic migraines
- Joint pain and arthritis
- Chronic fatigue syndrome
Also valuable for: Those who have tried elimination diets without success, suspect reactions to food chemicals, or want comprehensive testing with a proven protocol to follow.
What Happens Next
The LEAP Protocol: Turning Results Into Relief
MRT testing alone doesn't produce results—it's the dietary protocol that follows which creates symptom improvement. The LEAP (Lifestyle, Eating, And Performance) Protocol is a patented, phased elimination diet designed specifically to work with your MRT results.
Elimination Phase (Weeks 1-2)
You begin by eating only foods from your green (non-reactive) category. This rapidly reduces inflammatory load, allowing your gut and immune system to begin healing. Most people report noticeable symptom improvement within 7-10 days.
Expansion Phase (Weeks 3-12)
As symptoms improve, you systematically reintroduce additional green foods and untested foods, gradually expanding your diet while monitoring symptoms carefully.
Trialing Reactive Foods (Weeks 12+)
At this stage most people can successfully reintroduce and tolerate their previously reactive foods, especially when consumed in moderation.
Long-Term Maintenance
You'll have a clear understanding of which foods you tolerate well and which to limit. The goal isn't permanent restriction—it's sustainable, individualized nutrition that keeps you symptom-free.
Expected Timeline for Results
Days 7-10: 50% improvement is typical
Weeks 2-4: 50-70% symptom reduction is common
Weeks 8-12: 70-90% symptom resolution for most people
Explore our Full Spectrum Healing Program which includes MRT testing and the LEAP Protocol →
Is This Right For You?
MRT Testing: Who Benefits Most
✓ MRT Is Ideal If You…
- Have chronic symptoms despite normal test results
- Suspect food triggers but can't identify which ones
- Have tried elimination diets without clear success
- Want comprehensive testing including food chemicals
- Are ready to commit to dietary changes with expert guidance
- Want the most accurate food sensitivity test available
MRT May Not Be A Good Fit If…
- You are not able to make dietary changes
- You don't have symptoms
- Your symptoms are clearly not food-related (though you'd be surprised how many are!)
- You have a very tight budget
Getting Started
How to Get MRT Testing
MRT testing is most effective when paired with the LEAP Protocol and professional guidance from a Certified LEAP Therapist (CLT).
The Process
- Initial Consultation: Comprehensive review of your health history, symptoms, and goals
- Blood Draw: Testing kit mailed to your home; arrange local blood draw (we guide you through this)
- Results Review: Detailed review of your results and personalized LEAP Protocol design
- Implementation: Begin your protocol with ongoing support, regular check-ins, and protocol adjustments
- Long-Term Success: Transition to sustainable maintenance plan with the tools to maintain your health independently
Investment
MRT testing with LEAP Protocol implementation typically ranges from $1,500-$3,000 depending on the level of support included. Most practitioners offer package pricing. Insurance coverage is common.
Common Questions
Frequently Asked Questions About MRT Testing
How long does it take to get MRT test results?
MRT test results typically take 10-14 business days from when the lab receives your blood sample. Your Certified LEAP Therapist will then spend time analyzing your results and designing your personalized protocol before your results consultation.
Does insurance cover MRT testing?
MRT testing is rarely covered by insurance as it's considered specialized functional medicine testing. However, some HSA and FSA accounts may reimburse the cost. We recommend checking with your specific plan. The investment typically ranges from $400-$795 including the test and protocol design.
Can I do MRT testing if I'm already on an elimination diet?
Yes, you can do MRT testing while on an elimination diet. Unlike IgG testing (which requires exposure to foods), MRT measures your white blood cells' inflammatory response, so it works regardless of what you're currently eating. However, you'll get the most comprehensive results if you've been eating a varied diet recently.
What's the difference between MRT and standard allergy testing?
Standard allergy tests (IgE) measure immediate, potentially life-threatening allergic reactions (like peanut anaphylaxis). MRT measures delayed food sensitivities that cause chronic inflammation and symptoms like digestive issues, headaches, fatigue, and skin problems. These are different immune responses requiring different tests.
How often do I need to repeat MRT testing?
Most people don't need to repeat MRT testing. Once you identify your triggers, heal your gut, and learn to recognize your body's responses, you can maintain results long-term. Some people choose to retest after 1-2 years if their health status changes significantly or if they want to expand their diet further.
Megan Pennington, BSc in Dietetics & Human Nutrition (McGill University), Certified LEAP Therapist (CLT)
Megan Pennington is a naturopathic practitioner and integrative health specialist with over 20 years of clinical experience. She is a Certified LEAP Therapist and 2025 Global Recognition Award Winner for Advancing Science-Based Natural Healing. As founder of MP Integrative Health, Megan specializes in helping clients with chronic conditions achieve lasting relief through personalized functional medicine protocols.
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