The MSG Panic: The Letter That Poisoned a Cuisine

For decades the sign hung in the windows of Chinese restaurants across the English-speaking world, printed on card or worked into the menu in reassuring capitals: NO MSG. It was an apology and a defence at once, a small white flag run up by owners who had grown tired of customers asking whether the food would give them a headache, a racing heart, a numbness at the back of the neck. No other cuisine felt obliged to make this promise. French restaurants did not swear off butter; Italian ones did not disavow parmesan, which is dense with the very compound in question. Only Chinese food carried the mark of suspicion, and it carried it because of a single letter, published in one of the world’s most respected medical journals in the spring of 1968, that gave a vague cluster of sensations a name — and hung that name on a whole people’s cooking.

The kernel: a real compound, a real letter, a real early study

In a kernel piece the honest thing is to lay out everything that is genuinely true first, because there is more of it here than either side of the argument usually admits.

Monosodium glutamate is real, and it does something real. It was isolated in 1908 by a Japanese chemist named Kikunae Ikeda, working at Tokyo Imperial University, who had been puzzling over why a broth made from kombu seaweed tasted so satisfying in a way that could not be reduced to sweet, sour, salty or bitter. He identified the responsible substance as glutamic acid, and he named the taste it produced umami — a fifth basic taste, savoury and mouth-filling. Ikeda patented a method of producing its sodium salt, monosodium glutamate, and a company called Ajinomoto began selling it as a seasoning. The point that the whole later panic would obscure is that glutamate is not exotic. It occurs naturally, and abundantly, in tomatoes, mushrooms, aged cheeses, cured meats, soy sauce, fish sauce and human breast milk. When you taste the deep savour of a ripe tomato or a wedge of parmesan, you are tasting free glutamate. MSG is simply that same flavour molecule, isolated and made pourable.

The letter is real too, and it matters that we name it precisely. In April 1968 the New England Journal of Medicine published a short letter under the heading “Chinese-Restaurant Syndrome,” signed by a doctor named Robert Ho Man Kwok. He described a strange set of symptoms — numbness at the back of the neck spreading to the arms, general weakness, palpitations — that came over him about twenty minutes after eating at Chinese restaurants in the United States. He speculated about possible causes, listing soy sauce, cooking wine, the high sodium content, and monosodium glutamate among them. It was a tentative, musing letter, the kind of thing a curious physician might jot down. It named several suspects. The readers, and then the researchers, and then the public, seized on one.

And there was, for a while, a genuine scientific thread that made the seizing feel responsible. In 1969 the neuroscientist John Olney published experiments showing that very large doses of MSG, injected under the skin of infant mice, could damage neurons in the developing brain. This was real laboratory work in a serious journal, and it gave the anecdotal letter a mechanism to lean on. The fear now had a molecule, a syndrome, a name and a study behind it. It looked, for a moment, exactly like science working.

The fork: where a musing letter became a verdict

The precise point at which the record forks off into myth is the leap from Olney’s mice to the human dinner plate, and it is worth slowing down on, because it is the same overreach that powers a hundred food scares.

Olney’s mice were injected with enormous quantities of MSG, or fed doses vastly beyond anything a person could consume in food, at a developmental stage that made their brains uniquely vulnerable. Eating a plate of noodles seasoned with MSG does nothing of the kind. When glutamate is eaten, the gut metabolises the great majority of it before it ever reaches the bloodstream in quantity, and the blood-brain barrier guards the adult brain against exactly the kind of surge the injections produced. A finding about subcutaneous injection in infant rodents was quietly transformed, in the public mind, into a warning about seasoning your dinner. The mechanism looked solid precisely because a real study existed; almost nobody checked what the study had actually done.

Then came the part the panic never absorbed: researchers tried, repeatedly and carefully, to reproduce “Chinese Restaurant Syndrome” in controlled conditions, and they could not. In double-blind trials, where neither the subjects nor the testers knew who had received MSG and who had received a placebo, people who were certain MSG made them ill proved unable to tell whether they had eaten it. Some reactions appeared in both groups equally; some appeared only when subjects believed they had taken MSG. A handful of studies found that a small number of individuals, given very large doses of pure MSG on an empty stomach without food, reported mild and transient symptoms — but these did not reliably reproduce when the MSG was taken with a meal, as it always is in real life. A comprehensive review commissioned by the U.S. Food and Drug Administration and carried out by the Federation of American Societies for Experimental Biology, published in 1995, concluded that MSG was safe for the general population at normal levels of consumption. MSG has held the FDA’s “generally recognised as safe” status throughout. The syndrome, chased across three decades of laboratories, kept dissolving on contact with a blind test.

The part the science can’t quite reach: why one cuisine

Here the story stops being about biochemistry, because a chemical does not explain the geography of a fear. Monosodium glutamate was, at the very moment the panic took hold, sitting in an enormous share of Western processed food. It was in tinned soup, in stock cubes, in salad dressings, in crisps and snack foods, in the seasoning of fried chicken. A mid-century American consumer was very likely eating more MSG from a can of soup or a bag of savoury snacks than from the occasional restaurant meal. Yet no one coined “Campbell’s Soup Syndrome,” and no diner sign ever read NO MSG beside a picture of a hamburger. The fear attached itself, specifically and durably, to Chinese food — and it is neither an accident nor a coincidence that it did.

This is the dimension the polite version of the story tends to skip, and it deserves to be named plainly, as history rather than as accusation. “Chinese Restaurant Syndrome” arrived in a Western culture with a long, ugly tradition of treating Chinese cuisine and Chinese people as vaguely unclean, mysterious and threatening — the old slander of “dirty” foreign kitchens, the suspicion of unfamiliar ingredients, the reflex that codes the food of an immigrant community as suspect in a way the food of the dominant culture never is. The syndrome gave that inherited unease a scientific-sounding name and a molecule to point at. It let a diner blame a headache not on the three beers or the enormous portion or the long day, but on the alien seasoning in the alien restaurant. An additive present in half the Western pantry became a marker of one immigrant cuisine’s untrustworthiness. The chemistry was universal; the blame was selective, and the selection followed the contours of prejudice.

The naming stuck with remarkable tenacity. “Chinese restaurant syndrome” entered medical literature and, eventually, dictionaries; it was still a defined entry in Merriam-Webster decades later, prompting a public campaign — led in part by Ajinomoto under the banner “Redefine CRS” in 2020 — to have it reconsidered as an outdated and offensive term. Restaurateurs, meanwhile, absorbed the cost for two generations, stripping a harmless and delicious seasoning out of their cooking and advertising the absence, effectively apologising for a crime that the laboratories could not find.

The journey, and a possible prank at the source

There is a strange coda to the origin of it all. In 2018, a retired orthopaedic surgeon named Howard Steel claimed, in an interview for the podcast and public-radio project This American Life, that he had written the original 1968 letter himself as a joke — inventing the exotic-sounding name “Ho Man Kwok” and the syndrome on a bet with a colleague, never imagining a prank in a letters column would launch a fifty-year panic. The claim is genuinely disputed. Researchers subsequently found evidence that a real Dr Robert Ho Man Kwok had existed, had worked at the National Biomedical Research Foundation, and appears to have genuinely written the letter; family members came forward. Steel died before the matter could be pinned down, and the likeliest reading is that the letter was sincere and Steel’s deathbed claim was itself the fiction. But the very fact that a prank origin felt plausible — that a whole cuisine’s reputation could rest on something that might have been a gag in a medical journal — tells you how thin the foundation always was.

What carried the fear was never the strength of its evidence; it was the same set of forces that keeps every food scare aloft long after the science has moved on. A named syndrome feels more real than an unnamed doubt. A single memorable study — Olney’s mice — outweighs a dozen boring null results in the public imagination. And a fear that lets people explain an unpleasant bodily sensation by pointing at an outside culprit is far more comfortable to hold than the alternative, which is that they simply ate and drank too much. The pattern is identical to the way a retracted study kept a health myth alive for decades, and to the way the egg spent fifty years convicted on a mechanism that felt obvious. A vivid story beats a quiet correction every time.

What the panic was really about

The people who avoided MSG were not fools, and it would be a cheap ending to call them one. They were doing what all of us do: trusting a warning that came dressed in the authority of a famous journal and a real experiment, and preferring a nameable cause to a shapeless one. If you feel unwell after a meal, “it was the MSG” is a tidier, more actionable story than “I overate,” and tidiness is what frightened people reach for.

But the MSG panic carried something heavier than an ordinary food fear, and that is why it deserves to be remembered honestly. It shows how easily a genuine scientific thread — a real compound, a real letter, a real study — can be woven into a garment that fits a pre-existing prejudice. The additive was everywhere; the fear settled on the food of a particular people, because the culture was already primed to find that food suspect. Strip out the biochemistry and what remains is a lesson about how bias borrows the language of science to launder itself: give an old suspicion a molecule and a syndrome, and it can pass as caution for fifty years.

The seasoning, all the while, was doing nothing but making the food taste better — the same savoury depth Ikeda found in his seaweed broth in 1908, the same glutamate glowing in a tomato or a rind of parmesan. The panic was never really about the plate in front of the diner. It was about who had cooked it, and whether they could be trusted. That is the part the NO MSG signs were quietly answering, and the part the double-blind trials were never designed to test.