Sometimes I hate grocery shopping. Every time I wander down one of the aisles, I am visually assaulted with a barrage of various claims: Low Sodium! Heart Healthy! No fat! After a point, foods are laying claim to any appealing phrase they can use to convince you that their food should be purchased, and the most confusing and misleading of all is the claim ‘MSG Free!’ because so few of us actually know what MSG is. If the companies proclaim they don’t have it, it must be bad, right? Right?
Well, what is MSG? MSG, or monosodium glutamate, is a kind of salt. When we say the word salt colloquially, we are generally referring to table salt, or sodium chloride (NaCl); however, in a scientific sense, a salt is simply a compound composed of two oppositely charged molecules. For instance, Na+ and Cl– (sodium chloride) or K+ and OH– (potassium hydroxide) are both examples of a positive particle paired with a negative particle. Though both table salt and MSG contain the same positively charged molecule (sodium), MSG contains a different negative partner called glutamate. Glutamate is a type of amino acid, or protein building block. In fact, glutamate is one of the most abundant naturally occurring amino acids and is found in foods we eat every day, such as tomatoes, cheese, mushrooms, and meat. Glutamate is also produced by the human body and necessary to perform many brain functions, as it is the most abundant excitatory neurotransmitter, a chemical messenger in the brain. As a food additive, glutamate is responsible for many of the flavors that we consider to be savory or, as the Japanese title it, umami. The salt form of MSG, therefore, is added to many dishes to increase this savory flavor, as well as to reduce the amount of table salt necessary for flavoring.
It wasn’t until the 1960s that MSG began to appear negatively in the public eye, when a letter was published in the New England Journal of Medicine claiming that the use of MSG at a Chinese restaurant had been responsible for a plethora of symptoms in the writer, such as “numbness of the neck, arms, and back with headache, dizziness, and palpitations.” This single article led to widespread, unfounded articles with exceptionally racist headlines: ‘Chinese Food Make You Crazy? MSG is Number One Suspect,’ ‘Chinese Chow Numbs Some.’ As Asian cuisine tends to use MSG to achieve the umami flavor, the fear of MSG was inexorably linked to general American xenophobia. The phenomenon was titled “Chinese Restaurant Syndrome,” even in official scientific publications and in the Merriam-Webster dictionary. Even today, the link between MSG and Chinese food is hard to dissolve, and many Chinese restaurants feel the need to advertise that they do not use MSG in their food, for fear of losing customers.
Moving past the racist origins, does MSG actually negatively affect humans in any way? The overabundance of glutamate (not MSG) in the brain has been linked with several neurological conditions, as has the deficit of glutamate; however, neither of these have been linked to the ingestion of MSG itself. There have been several studies over the years looking to link MSG to negative health effects, but these studies have found one of two results: (1) MSG is not linked with any health concerns or (2) the experimental design was not constructed to provide accurate scientific data or was unable to be replicated. For instance, studies asked leading questions or contained too few test subjects to be considered in any scientifically meaningful capacity. At the level of food ingestion, MSG has not been shown to elicit any negative effects in humans, as all studies that have shown problematic responses in the lab have been conducted at levels far beyond the natural human consumption. In fact, recent studies have begun to investigate the positives of MSG consumption, with a focus on its effects on satiety and energy consumption in overweight individuals.
Despite this, MSG sensitivity is still reported by some people. This response is not labelled as an allergy; when a person exhibits an immediate food allergy, a protein called IgE is generally present in the response. In contrast, the IgE protein has not been seen as part of the MSG sensitivity response, suggesting that the response cannot be labelled as a typical allergy. For people who report these symptoms, the best solution is to avoid consuming MSG; for the rest of us, the FDA’s recommendation that MSG is safe for consumption still holds true.
So, should we worry about MSG? Well—no more than we worry about table salt: everything in moderation, after all. The unfortunate truth is that we likely wouldn’t be worried about MSG to this extent if it hadn’t initially been linked to our cultural xenophobia. As MSG has been an additive for over 100 years, and both sodium and glutamate have been part of the human diet for thousands of years, I hope that learning the science and history behind our fear will help you make an educated decision for your own diet.
Marissa Tranquilli is a PhD candidate in the chemistry department at the University of Chicago. She hopes to use her scientific experience and background in English Literature to improve the way scientists communicate with each other and with the rest of the world.