Does Dietary Monosodium Glutamate Cause Neuro-toxicity on The Central Nervous System? A Review

Monosodium glutamate (MSG) is an additive which is substantially applied in commercially processed foods in order to increase the flavor and sapidity and make a unique flavor which cannot be provided by any other ingredient. Since the discovery of endogenous amino acid glutamate (as a neurotransmitter) in human body, the possible toxicity of exogenous glutamic acid has attracted the attention of numerous scholars. Accordingly, various animal studies have been documented on toxic impacts of MSG on different parts of the body including central nervous system, liver, adipose tissue, reproductive organs, and other systems. Thus, since that time, the safety of MSG has repeatedly been checked and reaffirmed within the scientific communities due to the contradict results. This literature review article specifically aimed to discuss the probable safety of dietary MSG for central nervous system and also provide an integrated information from several studies documented on possible neurotoxic effects of monosodium glutamate on glutamate receptors of Central Nervous System in order to elevate the public awareness about it.

Literature search of this review was done by keywords of “sodium glutamate” “monosodium glutamate”, “MSG”, “central nervous system”, “CNS”, “neurotoxicity”, toxic effects of MSG on “glutamate receptors”, “hypothalamus” and “pituitary” in Google Scholar and PubMed databases and almost all of the 70 relevant articles from 1984-2021 were considered and among those with similar contents, newer ones were included and the others were excluded. Finally, 32 articles were used to write this literature review article.

Collecting the results of all studied articles seems to supports the hypothesis of safety. In fact, it seems that MSG as a food additive within the limited amounts as well as natural levels of glutamic acid which is present in food supplies provides no serious hazard to the human CNS.