"Chinese salt”: Different sides of monosodium glutamate
Monosodium glutamate (MSG) or “Chinese salt”, recently became the most popular yet the most controversial food ingredient. Debates over this food enhancer today have involved consumers, scientists, physicians and government officials, however, even after FDA approval people keep linking it with Chinese Restaurant Syndrome. A comprehensive scientific review on Monosodium glutamate (MSG) shows no side effects, but this controversial ingredient keeps us on tenterhooks being associated with various forms of toxicity and metabolic disorders.
Mystery of umami taste
Monosodium glutamate (MSG) application has increased over time and can be found in many different ingredients and processed foods like produced soups, chips, crackers, salad dressings, frozen dinners and a myriad of other products. We used to call it “savoury” while in Japan they call it the fifth taste — “umami” (1). It is confirmed that the tongue has glutamate receptors and recognizes this specific taste.
Glutamate’s biochemical functions
MSG belongs to a larger group of chemicals that is named “glutamate”. Glutamate is one of many different amino acids which are considered to be the building blocks of proteins (2).
Our bodies are not only familiar with glutamate as an element, although it shows up naturally in foods like scallops and tomatoes, as well as fermented products like parmesan cheese (1). Glutamate is the one which determines the taste of these products, however it works only when glutamate is in “free” form, not bonding with other amino acids in proteins.
Glutamate is produced by brain assist and works as a neurotransmitter. Dietary glutamate, including one from MSG, also helps the digestive system giving intestines the energy (2).
MSG is the sodium salt of the amino acid, glutamic acid, and a form of glutamate. Added to the food it enhances the flavours the same way that glutamate does.
According to one of the Harvard Law School students' papers, Americans consume around 11 grams of glutamate from natural protein sources and less than 1 gram of glutamate from MSG per day. While Asians consume three times more: for instance, Taiwanese consume 3 grams of glutamate from MSG per day (2).
Chinese Restaurant Syndrome
However, not everyone is optimistic about glutamate. In 1968 a letter published in the New England Journal of Medicine sparked worries about ingesting MSG. Author’s numbness in the back of his neck and general weakness after eating at Chinese restaurants were linked with MSG. After a while the number of publications against food enhancers and a list of supposed symptoms attributed to MSG grew.
Today “Chinese restaurant syndrome” (CRS) includes headaches, sweating, nausea and facial pressure that usually occur 20 minutes after consumption of a meal rich in MSG (1,3). The symptoms are temporary, not life-threatening and most patients recover on their own.
A threat to public health?
Extreme examples of negative effects attributed to MSG concerns CNS disorder, obesity, disruptions in adipose tissue physiology, hepatic damage, reproductive malfunctions and asthma. A connection between toxic effects and the consumption of MSG could however never be convincingly proven.
Researchers haven't backed up claims that physical symptoms develop after eating MSG. There were studies that did find some correlation between MSG consumption and physical effects yet the evidence was too weak. For instance, a study that analysed responses of 130 people who thought they were sensitive to MSG found that some individuals may show more CRS symptoms when eating the ingredient without any other food. However, when participants ingested the MSG serving as part of their breakfast, their symptoms disappeared (1).
No hard evidence
Anti-MSG activism together with irrelevant pseudo-scientific publications has labeled food allergy symptoms a CRS and resulted in public confusion surrounding MSG. A 2018 survey of U.S. consumers showed that respondents still had negative opinions of the ingredient, even though some people were confused about the difference between MSG and regular table salt.
Moreover, the FDA considers MSG to be "generally recognized as safe.Some of the world's largest food safety governing bodies have approved the ingredient, too, including JECFA, an international scientific committee administered jointly by the Food and Agriculture Organization of the United Nations and World Health Organization (1).
- Leslie Nemo MSG Isn't Bad For You, According to Science. Discover Magazine. December 30, 2020. Available at: https://www.discovermagazine.com/health/msg-isnt-bad-for-you-according-to-science
- Singh, Monica. Fact or Fiction? The MSG Controversy (2005 Third Year Paper). Available at: http://nrs.harvard.edu/urn-3:HUL.InstRepos:8846733
- Niaz, K., Zaplatic, E., & Spoor, J. (2018). Extensive use of monosodium glutamate: A threat to public health?. EXCLI journal, 17, 273–278. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5938543/
Illustration: Jason Tuinstra/Unsplash.com
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