Ingredient Analysis 5 min read

MSG and Food Sensitivity: What the MRT Panel Reveals

Kerry Watson, NTP, RWPKerry Watson, NTP, RWP
Nutritional Therapy Practitioner & Registered Wellness Professional • Evidence-based food sensitivity guidance

MSG is one of the most controversial substances in the food supply, and it is one of the 27 chemical additives specifically tested on the MRT 176 panel. You might think it is perfectly safe or a hidden poison, but the science behind mediator release testing tells a more nuanced story. Some people’s immune systems react to MSG, and for them, it is a clinically significant trigger.

In This Guide

What MSG Actually Is

Monosodium glutamate is the sodium salt of glutamic acid, an amino acid that occurs naturally in foods like tomatoes, parmesan cheese, and soy sauce. The manufactured form is the white crystalline powder added to processed foods. It was first isolated by Japanese chemist Kikunae Ikeda in 1908 and is responsible for the umami taste.

The FDA classifies MSG as “Generally Recognized as Safe”. This is technically accurate for the general population, but GRAS status doesn’t mean it is universally tolerated. It just means it is not acutely toxic at normal doses for most people. Aspirin is also GRAS, but millions of people can’t take it.

This distinction matters because MSG sensitivity is not an allergy. It is a non-IgE mediated immune response, which is the kind the MRT is specifically designed to detect. Traditional allergy tests like skin pricks and IgE blood panels will miss it completely.

MSG and the MRT Panel

The Mediator Release Test measures your white blood cells’ volumetric response to 176 substances, including MSG. When your blood is exposed to MSG in the lab, the test measures whether your immune cells release inflammatory mediators like prostaglandins, cytokines, histamine, and leukotrienes.

Your results will classify MSG as:

Green

Low reactivity. MSG is unlikely to trigger a significant mediator response in your body.

Yellow

Moderate reactivity. Avoid during Phase 1 and Phase 2. Reintroduce carefully in Phase 3 under CLT guidance.

Red

High reactivity. Avoid completely through all phases. MSG is a confirmed trigger for your immune system.

This is why the whole debate over whether MSG is safe misses the point entirely. It is safe for people whose immune systems don’t react to it. It is a clinically significant trigger for people whose MRT shows reactivity. The test resolves the debate on an individual basis.

Symptoms of MSG Sensitivity

Because MSG sensitivity is a mediator-driven response and not an IgE allergy, your symptoms can be delayed up to 72 hours and affect multiple body systems. Common reported symptoms include:

Neurological

  • Headaches and migraines
  • Brain fog and difficulty concentrating
  • Dizziness
  • Numbness or tingling (face, neck, arms)

Digestive

  • Bloating and abdominal cramping
  • Nausea
  • Diarrhea
  • IBS-like flares

Systemic

  • Fatigue and lethargy
  • Joint pain and muscle aches
  • Heart palpitations
  • Flushing and sweating

Skin

  • Hives and rashes
  • Eczema flares
  • Flushed or “hot” skin
  • Under-eye circles

The delay between consumption and symptoms is what makes MSG sensitivity so difficult to identify without testing. You might eat Chinese takeout on Tuesday and blame your Wednesday migraine on stress, the weather, or your sleep. You never connect it to the MSG in the soy sauce, broth, and seasoning.

The 12+ Hidden Names for MSG

This is where MSG avoidance gets difficult. The FDA only requires the label monosodium glutamate when pure MSG is added. But free glutamate is the same compound, and it can be introduced through processed ingredients that are not labeled as MSG. These ingredients contain significant amounts of free glutamic acid:

Always Contains Free Glutamate Often Contains Free Glutamate
  • Monosodium glutamate
  • Hydrolyzed vegetable protein
  • Hydrolyzed plant protein
  • Autolyzed yeast extract
  • Yeast extract
  • Sodium caseinate
  • Calcium caseinate
  • Textured protein
  • “Natural flavors”
  • “Seasonings” or “spices”
  • Bouillon, broth, stock
  • Maltodextrin
  • Whey protein concentrate
  • Soy protein isolate
  • Anything “protein-fortified”
  • Anything “enzyme-modified”

This is why products labeled as having no added MSG can still contain significant free glutamate. The label means they didn’t dump in a bag of pure MSG, but the hydrolyzed soy protein, yeast extract, and natural flavors in the ingredient list are delivering the same compound through the back door.

Where MSG Hides in Grocery Products

MSG and free glutamate are most concentrated in these product categories:

  • Chips and flavored snacks like Doritos, Cheetos, flavored nuts, and seasoned crackers
  • Canned and instant soups, which nearly all contain yeast extract or hydrolyzed protein
  • Frozen meals and TV dinners where natural flavors and soy protein isolate are standard
  • Salad dressings and marinades, especially ranch, Caesar, and Asian-style dressings
  • Seasoning packets like taco seasoning, ranch dip mix, and gravy packets
  • Deli meats and sausages where natural flavors and sodium caseinate are common
  • Fast food, where it is used extensively in sauces, breading, and seasoning blends
  • Health foods like protein bars, meal replacements, and flavored supplements

We analyzed over 20,000 grocery products and confirmed that avoiding MSG requires reading every single ingredient list or using a tool that does it for you.

What to Do If MSG Is on Your Red List

  1. Eliminate all sources of added free glutamate. Use the hidden names table above to identify MSG in ingredient lists, and when in doubt, just skip it.
  2. Cook from single ingredients during Phase 1. Meat, vegetables, fruit, and plain grains are naturally low in free glutamate. See our Phase 1 recipes for ideas.
  3. Use the Food Checker to search any packaged product against the MRT panel before buying.
  4. Watch for natural flavors and yeast extract because these are the two most common vehicles for hidden glutamate in products that claim to have no MSG.
  5. Be cautious with naturally high-glutamate foods. Parmesan cheese, aged cheeses, soy sauce, fish sauce, and miso contain naturally occurring glutamate. Your CLT will guide you on whether to include these.
Check Products for MSG and Hidden Triggers

PRACTITIONER INSIGHT

“The gut-brain axis connects the enteric nervous system to the central nervous system through the vagus nerve. When gut microbial balance is disrupted — often by incompletely digested proteins and carbohydrates — pathogenic bacteria produce lipopolysaccharide (LPS) endotoxins that cross the blood-brain barrier and trigger neuroinflammatory responses. This is one reason why MSG-reactive clients often report neurological symptoms like brain fog, migraines, and mood disturbances alongside digestive issues.”

— Kerry Watson, NTP, RWP • About Kerry

References: Mayer, E. A., Tillisch, K., & Gupta, A. (2015). Gut/brain axis and the microbiota. Journal of Clinical Investigation, 125(3), 926–938.

Related Resources

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Medical Disclaimer: This data is algorithmically generated based on USDA databases and is not medical advice. Always consult your Certified LEAP Therapist.