MRT vs IgG vs ALCAT: Which Food Sensitivity Test is Best?
MRT vs IgG vs ALCAT: Which Food Sensitivity Test Should You Choose?
If you’re experiencing chronic digestive issues, migraines, skin problems, or unexplained fatigue, food sensitivity testing can help identify your triggers. But with multiple tests on the market, choosing the right one matters. This guide compares the three most common food sensitivity tests: MRT (Mediator Release Test), IgG antibody panels, and ALCAT (Antigen Leukocyte Antibody Test).
Quick Comparison
| Feature | MRT 176 Panel | IgG Food Panel | ALCAT |
|---|---|---|---|
| What it measures | Total mediator release (all immune pathways) | IgG antibodies only | White blood cell size changes |
| Substances tested | 176 (foods + chemicals) | 90-200 (foods only, typically) | 100-450 (foods + chemicals) |
| Chemical additives | Yes — 30+ (dyes, preservatives, sweeteners) | Rarely included | Yes, in expanded panels |
| Reaction types detected | Type I, III, and IV hypersensitivity | Type III only | Type I and III (partial) |
| Clinical protocol included | Yes — LEAP elimination diet | Generic guidelines only | Rotation diet guidelines |
| Practitioner support | Certified LEAP Therapists (CLTs) | Varies by provider | Varies by provider |
| False positive concern | Low — measures actual cell response | High — IgG often reflects exposure, not sensitivity | Moderate — methodology debated |
| Reproducibility | High (split-sample studies show >90% consistency) | Variable across labs | Moderate |
Understanding Each Test
MRT (Mediator Release Test)
The MRT measures the end result of an immune reaction — the total volume of inflammatory mediators (cytokines, histamine, prostaglandins, leukotrienes) released by your white blood cells when exposed to food antigens. Because it captures the net inflammatory output regardless of which immune pathway triggered it, MRT detects reactions that antibody-only tests miss.
How it works: Your blood is drawn and your white blood cells are individually exposed to 176 substances. The test measures the volumetric change in cell suspension — when cells release mediators, the liquid-to-solid ratio changes measurably. Each substance is classified as Green (non-reactive), Yellow (moderate), or Red (reactive).
Key advantage: MRT is an “endpoint” test. It doesn’t measure one piece of the immune puzzle — it measures the final inflammatory output. This is why it captures Type IV (cell-mediated) reactions that IgG panels miss entirely.
Clinical protocol: Results feed directly into the LEAP (Lifestyle Eating and Performance) elimination diet, a structured protocol administered by Certified LEAP Therapists.
IgG Food Panels
IgG (Immunoglobulin G) panels are the most widely marketed food sensitivity tests. They measure the level of IgG antibodies your immune system produces against specific food proteins.
The controversy: Multiple medical organizations, including the American Academy of Allergy, Asthma & Immunology (AAAAI) and the European Academy of Allergy and Clinical Immunology (EAACI), have stated that elevated IgG levels to food may simply reflect exposure and tolerance, not sensitivity. In other words, the foods you eat most frequently will naturally produce higher IgG levels — even if they cause you no problems.
What IgG tests detect: Only Type III hypersensitivity reactions (immune complex-mediated). They miss Type IV reactions (delayed cell-mediated hypersensitivity), which are a significant portion of food sensitivity reactions.
When IgG tests may be useful: Some functional medicine practitioners use IgG panels as one data point alongside clinical symptoms. They’re less expensive than MRT and more widely available.
ALCAT (Antigen Leukocyte Antibody Test)
The ALCAT test measures changes in white blood cell size and number after exposure to food antigens. When immune cells react to a substance, they may swell or shrink.
How it differs from MRT: While both ALCAT and MRT involve exposing white blood cells to food antigens, ALCAT measures cell size changes while MRT measures mediator volume release. The distinction matters because cell size change is an indirect measurement — it infers an immune reaction occurred, whereas MRT directly quantifies the inflammatory output.
Reproducibility concerns: Some studies have questioned the test-retest reliability of the ALCAT methodology. When the same blood sample is split and tested twice, results don’t always match consistently.
Which Test Should You Choose?
The right test depends on your situation:
- Choose MRT if you want the most comprehensive detection (all immune pathways + chemical additives) and a structured clinical protocol (LEAP) with practitioner guidance
- Choose IgG if budget is a primary concern and you want a starting point for an elimination experiment — but interpret results cautiously
- Choose ALCAT if you want a larger food panel (up to 450 items) and your practitioner specifically recommends it
What to Do After Testing
Regardless of which test you choose, results are only valuable when paired with a structured elimination and reintroduction protocol. For MRT, this means working with a Certified LEAP Therapist to implement the LEAP diet phases.
You can also check how specific food products interact with the MRT 176 panel using our product assessment database of over 20,000 foods.
Frequently Asked Questions
Is MRT better than IgG testing?
MRT captures a broader range of immune reactions (Type I, III, and IV) while IgG panels only detect Type III. MRT also tests food chemicals (dyes, preservatives) that most IgG panels exclude. For comprehensive food sensitivity detection, MRT provides more actionable data.
Why don’t doctors recommend IgG testing?
Major allergy organizations have noted that elevated IgG to food often reflects normal immune exposure and tolerance, not pathological sensitivity. IgG testing can produce false positives for commonly consumed foods, leading to unnecessary dietary restrictions.
Can I take more than one test?
Yes, some practitioners use multiple tests for a more complete picture. However, MRT alone covers the broadest range of immune pathways, making additional testing often unnecessary.
Where can I get an MRT test?
Visit our MRT testing locations directory to find Certified LEAP Therapists, blood draw labs, and mobile phlebotomy services in your area.
Last updated: May 19, 2026