The claimEvidence A · guideline-tier
MSG is toxic ('Chinese Restaurant Syndrome')
The evidence
Originates from a 1968 uncontrolled letter; Geha 2000 double-blind challenge found only 2.3% responding, non-reproducibly — glutamate is the same molecule as in tomato and breast milk, safe at dietary doses.
The mechanism, in brief
In the decades after Kwok's letter, researchers tested the claim that "MSG makes you feel unwell" again and again in double-blind, placebo-controlled trials. The conclusion has been consistent: at the amounts eaten with food, it does not show up.
Sources (4)
- Geha, R. S., Beiser, A., Ren, C., et al. (2000). Review of alleged reaction to monosodium glutamate and outcome of a multicenter double-blind placebo-controlled study. Journal of Nutrition, 130(4S Suppl), 1058S-1062S. Double-blind placebo-controlled challenges failed to reliably reproduce MSG symptoms at dietary doses. Note: the id says JACI but this record is the J Nutr summary (PMID 10736382); the full trial report is geha-2000-msg-multicenter-challenge. Summary abstract: a multicenter double-blind placebo-controlled challenge in 130 people who reported MSG reactions; large doses given without food may elicit more symptoms than placebo, but responses were infrequent, inconsistent and not reproducible, and were not seen when MSG was given with food (abstract, PMID 10736382).
- Raiten, D. J., Talbot, J. M., & Fisher, K. D. (Eds.). (1995). Analysis of adverse reactions to monosodium glutamate (MSG), report prepared by FASEB for the U.S. FDA. Journal of Nutrition, 125(11), 2891S-2906S. Concluded MSG is generally safe at normal dietary intake. PubMed indexes the executive summary (PMID 7472671) without an abstract and the report text could not be re-read (publisher page blocked, 2026-09-25); FDA's MSG Q&A (fda-msg-qa) summarises this report's finding of transient, mild symptoms in some sensitive people after 3 g or more without food.
- Geha, R. S., Beiser, A., Ren, C., Patterson, R., Greenberger, P. A., Grammer, L. C., et al. (2000). Multicenter, double-blind, placebo-controlled, multiple-challenge evaluation of reported reactions to monosodium glutamate. Journal of Allergy and Clinical Immunology, 106(5), 973-980. 130 self-selected people who reported MSG reactions were challenged with 5 g of MSG and with placebo without food (protocol A): 50 (38.5%) responded to MSG only, 17 (13.1%) to placebo only and 19 (14.6%) to both. Rising doses raised response rates, but only 19 of 37 MSG-only responders reacted the same way on retest; the 2 people who then responded to MSG but not placebo twice were challenged 3 times each with 5 g of MSG and with placebo in the presence of food, and each responded to only one MSG challenge. Conclusion: large doses without food may elicit more symptoms than placebo in people who believe they react, but no persistent or serious effects were seen and responses were not consistent on retesting (abstract, PMID 11080723).
- U.S. Food and Drug Administration. (2026). Questions and answers on monosodium glutamate (MSG) (content current as of 17 July 2026). FDA considers the addition of MSG to foods 'generally recognized as safe' (GRAS). Adverse event reports led FDA to ask FASEB to examine MSG safety in the 1990s; FASEB's report concluded that MSG is safe, and identified short-term, transient and generally mild symptoms (headache, numbness, flushing, tingling, palpitations, drowsiness) that may occur in some sensitive individuals who consume 3 grams or more of MSG without food; consuming more than 3 grams of MSG without food at one time is unlikely. An average adult eats about 13 g of glutamate a day from food protein, against about 0.55 g a day of added MSG (Q&A page, read 2026-09-25).