How a 1968 Letter Smeared MSG for 50 Years

On April 4, 1968, the New England Journal of Medicine published a short letter from Dr. Robert Ho Man Kwok complaining of numbness, weakness, and palpitations after eating at northern Chinese restaurants. He suggested cooking wine, sodium content, or possibly monosodium glutamate as the culprit. The letter was casual, the tone was speculative, and the editors gave it the headline 'Chinese-Restaurant Syndrome.' That phrase outlived the science by half a century.

MSG is the sodium salt of glutamate, an amino acid that occurs naturally in tomatoes, parmesan, mushrooms, and human breast milk. Kikunae Ikeda isolated it from kombu seaweed in 1908, gave the taste it produces a name — umami — and a Japanese company began selling it as a seasoning the next year. By 1968 it was already a staple in American processed food, hidden in soup mixes and canned vegetables that nobody was blaming for headaches.

The scare took off anyway. Newspaper columnists picked up the phrase. Researchers ran small studies, then larger ones. A 2000 multicenter trial in the Journal of Allergy and Clinical Immunology gave 130 self-identified MSG-sensitive subjects either MSG or placebo, in a double-blind crossover. Reactions did appear, but inconsistently and at roughly the same rate to placebo when MSG was given with food. The FDA classifies MSG as 'generally recognized as safe' and notes no consistent reproducible link to the symptoms Kwok described.

The stereotype outlasted the evidence because the food it attached to was foreign. In 2020 the dictionary publisher Merriam-Webster updated its entry for the syndrome's name to flag it as outdated and racially loaded. The chemistry, by then, had been settled for decades.