MSG (monosodium glutamate) has been blamed for a wide range of symptoms since the 1960s, but well-designed clinical trials have mostly failed to confirm these claims. When people were given MSG or placebo in controlled, blinded studies, most could not tell the difference and consistent symptom patterns did not emerge. The widely cited 'Chinese Restaurant Syndrome' has been largely debunked by research. Only one confirmed case of true immune-mediated MSG allergy has ever been published (in 2024).

An important practical point: free glutamate occurs naturally in large quantities in Parmesan cheese, ripe tomatoes, mushrooms, and soy sauce — all of which are established triggers — meaning reactions attributed to MSG in restaurant meals are more likely caused by other high-trigger ingredients in the same dish.