E621 Monosodium Glutamate (MSG) may be the most misunderstood food additive in history. Blamed for everything from headaches to brain damage, it has been demonized for decades. But what does the actual science say?
What Is MSG and Where Does It Come From?
MSG is the sodium salt of glutamic acid — an amino acid that occurs naturally throughout the food supply. Your body produces and uses glutamate every day.
Foods naturally high in glutamate:
- Parmesan cheese — 1,200 mg/100g
- Tomatoes — 140 mg/100g
- Mushrooms — 180 mg/100g
- Soy sauce — 1,090 mg/100g
- Human breast milk — 22 mg/100ml
Commercial MSG is produced through fermentation of sugarcane or corn — the same biological process used to make yogurt.
The “Chinese Restaurant Syndrome” Origin Story
In 1968, Dr. Robert Ho Man Kwok wrote a letter to the New England Journal of Medicine describing neck stiffness, palpitations, and weakness after eating at Chinese restaurants. The media coined the term “Chinese Restaurant Syndrome” and MSG was put on trial.
Decades of double-blind, placebo-controlled studies that followed told a different story:
When participants were given MSG without being told, reported symptoms did not differ statistically from those given a placebo.
The FDA, EFSA, WHO, and JECFA (the Joint Expert Committee on Food Additives) all classify MSG as Generally Recognized As Safe (GRAS).
What About Brain Damage?
In the 1960s, animal studies showed that very high doses of MSG could cause brain lesions. However, those doses were orders of magnitude higher than anything achievable through normal diet — and were administered by injection, not eaten.
Modern science has established that ingested glutamate does not cross the blood-brain barrier in meaningful amounts. The MSG you eat simply doesn’t reach the brain.
MSG’s Practical Benefit: Less Sodium
MSG contains 60% less sodium than table salt. When used in cooking, the same depth of flavor can be achieved with significantly less total sodium — which is why some dietary guidelines actually recommend MSG as a sodium-reduction strategy.
Who Should Be Careful?
According to scientific consensus, MSG at normal dietary levels is safe for the general population. However:
- Individuals with glutamate sensitivity: A very small number of people may experience headaches with very large doses.
- Asthma patients: Some studies suggest high MSG intake may trigger asthma symptoms in susceptible individuals.
Bottom Line
The fear of MSG is largely a myth unsupported by credible science. The more relevant concern is what MSG is typically found in — highly processed foods that also contain excessive salt, sugar, and saturated fat. The problem isn’t MSG; it’s the overall nutritional profile of the products that contain it.