Management of monosodium glutamate toxicity

Monosodium L-glutamate: a double-blind study and review

71 healthy subjects were treated with placebos and monosodium L-glutamate (MSG) doses of 1.5, 3.0 and 3.15 g/person, which represented a body mass-adjusted dose range of 0.015-0.07 g/kg body weight before a standardized breakfast over 5 days. The study used a rigorous randomized double-blind crossover design that controlled for subjects who had MSG after-tastes. Capsules and specially formulated drinks were used as vehicles for placebo and MSG treatments. Subjects mostly had no responses to placebo (86%) and MSG (85%) treatments. Sensations, previously attributed to MSG, did not occur at a significantly higher rate than did those elicited by placebo treatment. A significant (P < 0.05) negative correlation between MSG dose and after-effects was found. The profound effect of food in negating the effects of large MSG doses was demonstrated. The common practice of extrapolating food-free experimental results to 'in use' situations was called into question. An exhaustive review of previous methodologies identified the strong taste of MSG as the factor invalidating most 'blind' and 'double-blind' claims by previous researchers. The present study led to the conclusion that 'Chinese Restaurant Syndrome' is an anecdote applied to a variety of postprandial illnesses; rigorous and realistic scientific evidence linking the syndrome to MSG could not be found.

Chinese restaurant syndrome: a review

CRS is a benign, self-limited process that has an excellent prognosis for immediate and rapid recovery. While questions remain about exactly who is susceptible, how much MSG is needed, and even whether MSG is the sole etiologic agent, there appears to be little reason to embark on an extensive workup and treatment regimen with a presumptive diagnosis of MSG intoxication. Rather, knowledge of CRS and recognition of its associated signs and symptoms and its clinical course are important.