Most people think MSG is bad because of a single letter published in a medical journal in 1968, followed by decades of cultural anxiety that science has never been able to confirm. The FDA classifies MSG as “generally recognized as safe,” and the ingredient occurs naturally in foods most people eat every day without a second thought. So how did a common amino acid salt become one of the most feared food additives in America?
A 1968 Letter Started Everything
In April 1968, a Chinese American doctor named Robert Ho Man Kwok wrote a letter to the New England Journal of Medicine describing symptoms he experienced after eating at Chinese restaurants: numbness at the back of his neck radiating to both arms, general weakness, and heart palpitations. He speculated about three possible causes, including salt, cooking wine, and MSG. The letter wasn’t a study. It was a personal anecdote with no controlled testing. But Kwok gave his experience a name, “Chinese Restaurant Syndrome,” and that phrase stuck.
The response was immediate. The following month, the journal published eleven separate letters from readers who identified with Kwok’s experience. Media coverage amplified the idea, and within a few years, MSG had become shorthand for something vaguely toxic lurking in takeout food. The fact that MSG was already widely used in American processed foods, canned soups, and snack chips didn’t seem to matter. The fear attached specifically to Chinese cooking.
The Science Didn’t Back It Up
Researchers spent decades trying to reproduce the symptoms Kwok described under controlled conditions, and the results were consistently underwhelming. In multiple double-blind, placebo-controlled studies (where neither the participants nor the researchers knew who was getting MSG and who was getting a dummy substance), self-identified MSG-sensitive people could not reliably tell the difference. One study of 61 people who believed they reacted to MSG found no significant difference in symptoms between MSG and placebo. Another study involving 100 asthmatic patients produced the same result.
One larger trial did find that a dose of 5 grams of MSG (a very large amount, roughly five times what you’d get in a typical restaurant meal, taken on an empty stomach) produced a higher rate of symptoms compared to placebo. But even in that study, when researchers tried to confirm the reactions by repeating the challenge, the responses weren’t consistent. The same people didn’t reliably get the same symptoms twice. There are no diagnostic tests for “MSG sensitivity,” and the condition has never been formally recognized as a medical diagnosis.
An FDA investigation into the issue found no evidence that MSG in food caused the reported symptoms. MedlinePlus, the government’s consumer health resource, puts it plainly: studies have failed to find a conclusive link between MSG and the symptoms some people describe.
Your Body Already Handles Glutamate Daily
MSG is simply the sodium salt of glutamate, an amino acid that is one of the most abundant in the human diet. Your body produces glutamate on its own, and it plays a central role in digestion and brain function. When you eat MSG, your gut processes the glutamate the same way it handles the glutamate in a tomato or a piece of chicken.
The amount of free glutamate in everyday foods puts this in perspective. Per 100 grams, chicken contains about 44 mg of free glutamate, tomatoes contain 140 mg, mushrooms 180 mg, and walnuts 658 mg. Parmesan cheese contains 1,200 mg per 100 grams, and soy sauce has 1,090 mg. These are the same molecules. When you sprinkle parmesan on pasta or add soy sauce to a stir-fry, you’re consuming glutamate in quantities comparable to or exceeding what a dash of MSG powder would provide.
One concern that circulated for years was that dietary MSG might flood the brain with excess glutamate, since glutamate functions as a neurotransmitter. Research has firmly put this to rest. Normal dietary intake of MSG does not produce appreciable increases in blood glutamate levels, and the blood-brain barrier effectively blocks glutamate from passing into the brain. Brain glutamate levels only rise when blood concentrations are pushed up through extreme, non-physiological experimental methods that bear no resemblance to eating food.
Anti-Chinese Bias Shaped the Narrative
It’s hard to separate the MSG scare from its cultural context. The term “Chinese Restaurant Syndrome” didn’t just describe a set of symptoms. It tied those symptoms to a specific ethnic cuisine at a time when anti-Asian sentiment was common in the United States. MSG was used broadly across the American food industry, in everything from seasoning blends to canned vegetables, yet the panic focused almost exclusively on Chinese restaurants.
This selective suspicion is telling. People who reported headaches after eating Chinese food rarely questioned the MSG in their Doritos, Campbell’s soup, or ranch dressing. The framing made the ingredient seem foreign and suspect when it appeared in one context, while remaining invisible in another. Over time, food scholars and journalists have documented how xenophobia amplified what was always thin scientific evidence into a widespread cultural belief. The story of MSG is, in many ways, a story about who gets trusted in food culture and who gets scrutinized.
What Regulators Actually Say
The FDA classifies MSG as “generally recognized as safe,” the same category that includes salt, pepper, and vinegar. This designation means the scientific evidence is strong enough that MSG doesn’t require special approval to be used in food.
The European Food Safety Authority took a slightly more cautious approach in 2017, setting a group acceptable daily intake of 30 mg per kilogram of body weight per day for glutamate-based food additives. For a 150-pound person, that works out to about 2 grams per day. This limit was established as a precaution based on animal studies using high doses, not because of documented harm in humans at normal intake levels. Most people consume well within this range without trying.
MSG May Actually Help Reduce Sodium
One practical detail that often gets lost in the fear is that MSG contains roughly one-third the sodium of table salt: about 12 grams of sodium per 100 grams, compared to 39 grams in regular salt. Because MSG enhances the savory flavor of food, you can use less total seasoning and still get a satisfying taste. For people watching their sodium intake, swapping some salt for MSG is a straightforward way to cut sodium without making food bland.
This is one of the reasons MSG was developed in the first place. Japanese chemist Kikunae Ikeda isolated glutamate from seaweed broth in 1908, identifying it as the compound responsible for the savory taste he called “umami.” The goal was always to make food taste better with less, not to add something harmful.
Why the Belief Persists
If the science is this clear, why do so many people still believe MSG is harmful? Several factors reinforce the belief. First, the nocebo effect is powerful. If you expect MSG to give you a headache, eating food you know contains MSG can genuinely produce a headache. This is a real physiological response, but it’s triggered by expectation, not by the chemical itself. Blinded studies, where people don’t know what they’re eating, consistently fail to reproduce the same reactions.
Second, confirmation bias keeps the cycle going. A heavy, salty restaurant meal can cause bloating, thirst, or a headache for any number of reasons: overeating, high sodium, alcohol, dehydration. If you’ve been told MSG is the culprit, you’ll attribute those feelings to MSG and remember the experience as proof. The times you eat glutamate-rich foods without symptoms (parmesan, ripe tomatoes, soy sauce) don’t register as contradictions because you’re not looking for them.
Finally, “MSG-free” and “No Added MSG” labels on food packaging signal to consumers that MSG is something worth avoiding, creating a feedback loop. Companies add these labels because consumers want them, and consumers want them because the labels exist. The marketing reinforces the fear even as the science undermines it.