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.
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 involve different immune mechanisms: delayed hypersensitivity reactions mediated by inflammatory cells rather than IgE antibodies. These reactions are:
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.
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.
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.
MRT categorizes foods by severity of reaction:
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
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.
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
| 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 |
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.
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.
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.
As symptoms improve, you systematically reintroduce additional green foods and untested foods, gradually expanding your diet while monitoring symptoms carefully.
At this stage most people can successfully reintroduce and tolerate their previously reactive foods, especially when consumed in moderation.
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 →
MRT testing is most effective when paired with the LEAP Protocol and professional guidance from a Certified LEAP Therapist (CLT).
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.
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.
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.
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.
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.
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.
Functional Medicine for Chronic Conditions: IBS, Autoimmune, Pain, Fatigue & More
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