An Objective Look at the Science, Accuracy & Clinical Value
If you're researching food sensitivity testing, you've likely encountered two main options: MRT (Mediator Release Testing) and IgG antibody testing. Both claim to identify food sensitivities. Both involve a blood test. Both cost hundreds of dollars.
But they're fundamentally different tests measuring completely different things—and one has significantly better clinical validation than the other.
This comparison examines the science behind each test, their accuracy rates, clinical validation, and most importantly: which one actually helps you identify your food triggers.
We'll look at the evidence objectively, including research that's critical of both approaches, so you can make an informed decision about which test—if any—is right for you.
If you just want the bottom line before diving into the science:
MRT (Mediator Release Testing) has significantly stronger clinical validation, higher accuracy rates (94.5% sensitivity, 91.7% specificity), and better correlation with actual symptoms than IgG testing.
IgG testing measures antibodies that may indicate exposure to foods rather than sensitivity, leading to high rates of false positives and poor correlation with clinical food challenges.
However, this doesn't mean IgG testing is completely worthless or that MRT is perfect. Let's examine exactly what each test measures, the evidence supporting or refuting each approach, and when each might (or might not) be appropriate.
The most important difference between MRT and IgG testing is what they're measuring in your blood.
IgG tests measure the level of IgG antibodies your immune system has produced in response to specific foods. The theory is that elevated IgG antibodies to a food indicate you're "sensitive" to that food and should avoid it.
The problem: IgG antibodies are a normal immune response to foods you eat regularly. Research shows that IgG levels often correlate with frequency of consumption rather than adverse reactions. Healthy people eating a varied diet will have IgG antibodies to many foods without any symptoms.
MRT measures the actual release of inflammatory mediators (histamine, cytokines, prostaglandins, etc.) from your white blood cells when exposed to specific foods and chemicals. It measures the endpoint of all inflammatory pathways, not just one type of antibody.
Why this matters: Mediator release directly correlates with symptom production. If your cells release inflammatory mediators in response to a food, you're likely to experience symptoms. MRT captures this response regardless of which immune pathway is involved.
Analogy: IgG testing is like measuring whether you've been exposed to something (antibodies = exposure). MRT is like measuring whether that exposure causes actual inflammation (mediator release = inflammatory reaction).
The scientific and medical community has been largely critical of IgG food sensitivity testing:
Key study: A 2008 study in the Journal of Allergy and Clinical Immunology found that IgG levels did not correlate with clinical food challenges and concluded that IgG testing "cannot be recommended for the diagnosis of food allergy."
References:
1. Stapel, S.O. et al. "Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report." Allergy, 2008 Jul;63(7):793–6. PMID: 18489614
2. Gocki, J. & Bartuzi, Z. "Role of immunoglobulin G antibodies in diagnosis of food allergy." Advances in Dermatology and Allergology, 2016 Aug;33(4):253–6. View Article
MRT has more limited but more positive clinical validation:
References:
1. Oxford Biomedical Technologies. "MRT Publications & Research." nowleap.com. View Publications
2. Mediator Release - Clinical Overview. ScienceDirect. View Articles
3. Pennington, M. "Food Sensitivity Research." meganpennington.com. View Studies
| Factor | MRT (Mediator Release Test) | IgG Antibody Testing |
|---|---|---|
| What It Measures | Inflammatory mediator release from white blood cells | IgG antibodies to foods |
| Number of Items Tested | 176 foods AND chemicals | 90-200 foods (no chemicals) |
| Clinical Accuracy | 94.5% sensitivity, 91.7% specificity | Poor correlation with symptoms in most studies |
| Professional Endorsement | Used by Certified LEAP Therapists | Not recommended by major allergy organizations |
| Correlation with Symptoms | High - measures actual inflammatory response | Low - antibodies don't always cause symptoms |
| False Positives | Lower rate due to quantitative measurement | High rate - flags foods you eat regularly |
| Protocol Included | LEAP Protocol (structured, phased approach) | Varies - often just "avoid reactive foods" |
| Professional Guidance | Must work with Certified LEAP Therapist | Often sold direct-to-consumer |
| Cost | $400-$795 (test + protocol design) | $200-$500 (test only, usually) |
| Clinical Outcomes | 75-80% report significant improvement | Variable, limited data |
The fundamental problem with IgG testing isn't that it's measuring the wrong thing—it's that what it measures doesn't tell you what you need to know.
When you eat food regularly, your immune system produces IgG antibodies to components of that food. This is normal and healthy. It's part of oral tolerance—your immune system learning that dietary proteins are safe.
The result? IgG tests often show "reactions" to:
Multiple studies show that IgG levels correlate more strongly with how often you eat a food than with whether that food causes symptoms. This makes IgG testing particularly problematic because it can:
Example: You eat chicken every day for years. You develop IgG antibodies to chicken (normal exposure response). IgG test flags chicken as "reactive." You eliminate chicken unnecessarily while continuing to eat salmon (which you actually react to but eat rarely, so have low IgG levels).
MRT measures the release of inflammatory mediators—the chemicals that actually cause your symptoms. If your cells don't release mediators in response to a food, you're unlikely to have symptoms from that food regardless of antibody levels.
Food sensitivities can involve Type III hypersensitivity, Type IV hypersensitivity, mast cell activation, and other mechanisms. MRT captures the end result of ALL these pathways by measuring mediator release, while IgG testing only looks at one antibody type.
MRT tests reactions to food chemicals (salicylates, solanine, caffeine, food dyes) that IgG tests miss entirely. Many people react to chemicals within foods rather than the foods themselves.
MRT provides a quantitative measurement of reaction severity (green/yellow/red), allowing for a precise, phased protocol. IgG tests typically just show "positive" or "negative" or give numbers without validated clinical significance.
MRT testing requires working with a Certified LEAP Therapist who guides you through a structured, clinically validated protocol. This professional support significantly improves outcomes compared to "here's a list of foods to avoid."
In the interest of fairness, let's acknowledge scenarios where IgG testing might have some value:
Some practitioners use IgG testing as a starting point for elimination diets, fully acknowledging its limitations. The reasoning: even if results aren't perfectly accurate, they provide a structured list to try eliminating, which is better than random guessing.
The problem with this approach: You might eliminate foods you don't need to avoid while continuing to eat actual triggers, leading to frustration and abandoned protocols.
IgG tests are generally cheaper than MRT ($200-$400 vs $700-800). If cost is the absolute barrier and you can't afford MRT, an IgG test might be better than nothing—but with the strong caveat that you should view results skeptically and not eliminate foods long-term without noticing symptom improvement.
IgG testing can occasionally point someone in a useful direction despite its inaccuracy, but it's not a reliable diagnostic tool. If you're going to invest in food sensitivity testing, MRT's superior accuracy and clinical validation make it the better choice for most people.
MRT costs more than IgG testing. Is the extra expense justified?
| Cost Factor | MRT Testing | IgG Testing |
|---|---|---|
| Test Cost | $700-$800 | $200-$500 |
| Professional Expertise | Practitioners are specialized | Usually not specialized |
| Protocol Design | Included (LEAP Protocol) | Usually DIY from results |
| Ongoing Support | Included in most packages | Rarely included |
| Success Rate | >80% achieve improvement | Variable, poorly documented |
| Risk of Inaccuracy | Low (high accuracy) | High (false positives common) |
Our assessment: If you're going to invest in food sensitivity testing at all, MRT's superior accuracy, professional support, and validated protocol make it worth the additional cost for most people with chronic symptoms. The cost of months spent following inaccurate IgG results—eliminating the wrong foods while continuing to eat actual triggers—often exceeds the upfront price difference.
For most people with chronic symptoms, MRT is the clear choice due to its superior accuracy, clinical validation, and comprehensive approach including food chemicals.
IgG testing's high rate of false positives and lack of professional endorsement make it difficult to recommend despite its lower cost.
You could, but it's generally not recommended. The tests often give contradictory results (IgG flags foods MRT shows as safe), which creates confusion rather than clarity. Since MRT has superior accuracy and clinical validation, doing both is typically a waste of money. If you're going to test, choose the more accurate option.
Some naturopaths and functional medicine practitioners use IgG testing despite its limitations, often because they're unaware of MRT or because the lab they work with doesn't offer it. Ask your practitioner if they're familiar with MRT and whether they're a Certified LEAP Therapist. If cost is their concern, discuss that directly rather than defaulting to a less accurate test.
If your IgG test results helped you identify triggers and you're feeling significantly better, you may not need MRT. However, if you've been following IgG results without clear improvement, or if you're confused by the results (too many foods flagged, eliminated foods but still symptomatic), MRT testing would likely provide more accurate, actionable information.
Yes, MRT tests your reaction to wheat and other gluten grains. However, MRT does not diagnose celiac disease (that requires specific tests and endoscopy). If you have celiac disease, you must avoid gluten completely regardless of MRT results. MRT identifies non-celiac gluten sensitivity.
MRT is designed to identify food sensitivities, not allergies. Food allergies are IgE-mediated and follow a different immune pathway — and because allergic reactions tend to be immediate and unmistakable, they rarely require a test to identify. That said, MRT can detect mediator release triggered by allergic reactions in the blood, though most of the immune activity in true allergies occurs at the mast cell level rather than in circulating white blood cells. If you suspect a food allergy, standard IgE allergy testing is the appropriate diagnostic tool.
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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