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MSG: The Misunderstood Sodium Substitute

An image depicting monosodium glutamate.
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Monosodium glutamate (MSG), a flavor enhancer with an umami taste, is bad for us; at least that’s what we’ve been led to believe.

MSG was given a rather unsavory reputation after a respected medical journal published a letter describing Chinese Restaurant Syndrome – a term devised by the author who attributed his symptoms to eating Chinese food laced with MSG.

The syndrome has since been debunked, but the stigma around MSG has persisted for decades. Even today, people still believe the misinformation shared about MSG and the ingredient’s supposed adverse effects on health.

But did MSG ever deserve its distasteful status, or is it simply just a misunderstood constituent of South Asian cuisine? And, at a time when sodium consumption is under the spotlight, could this once-maligned ingredient be the key to reducing the sodium content of some of our favorite foods?

What is MSG?

MSG is the sodium salt of glutamic acid, the most abundant amino acid in nature. It’s naturally present in our bodies and is found in lots of everyday foods including tomatoes, cured ham and parmesan cheese – so you’re likely eating it without realizing!

MSG has a specific taste that Kikunae Ikeda, a Japanese chemistry professor, attributed to glutamate, the non-essential amino acid. He noted the savory taste in his rich seaweed broth was unique from the four basic tastes of sweet, sour, bitter and salty; he named it umami.

In 1908, Ikeda filed a patent for a process to extract glutamate from seaweed and stabilize it with salt; he dubbed his invention “the essence of taste”. A year later, Ikeda began commercial production of his MSG powder under the brand name “Ajinomoto” (meaning essence of taste). Today, MSG is still produced by the same company but using a different method. Instead of the lengthy process of extracting it from seaweed, MSG is made by fermenting starch, sugar beets, sugar cane or molasses in a process that is similar to the fermentation process used to make yogurt, vinegar and wine.

MSG powder is used sparingly in Chinese, Japanese and other South Asian cuisines and as a food additive to mimic savory flavors in ultra-processed products like soup mixes and ready-made sauces, cured meats and savory snacks, stock cubes and instant noodles.

“The most interesting thing about MSG is that it does not add flavor to food. It changes the way your taste buds perceive food adding the so-called fifth flavor group umami,” explains Allen Bixby, chef and author at notakeout.com. “MSG enhances our ability to enjoy the savory flavors related to meat and saltiness, along with sour tastes, while only containing about a third of the sodium content of table salt. It can in fact be used in lower sodium preparations to enhance flavors and have them perceived as salty.”

When exposed to water in foods or saliva, MSG separates into sodium and glutamate; the latter binds to receptors on the human tongue that sense the key flavor.

"It is considered a food flavor because the amino acid glutamate connects with a specific receptor in the taste buds, providing the umami taste,” explains Hellen Maluly, independent food industry and government consultant, professor of Food Chemistry and Sensory Science and member of the Brazilian Association of Sensory and Consumer Science.

However, it wasn’t until 2002, almost 100 years after Ikeda’s discovery, that the umami taste receptor was discovered and umami was confirmed as the fifth basic taste. Interestingly, the human body is unable to distinguish between synthetic MSG added to food and glutamate which occurs naturally; it metabolizes them both in the same way.

Unsavory reputation

MSG is one of the world’s most popular seasonings, but it’s well-known for its checkered history. Following the publication of a letter in the prestigious New England Journal of Medicine in 1968, MSG was given a rather unsavory reputation as a dangerous toxin.

In the letter, Dr. Robert Ho Man Kwok described symptoms of generalized weakness, palpitations and numbness in the arms after eating a meal at a Chinese restaurant. Kwok thought several ingredients could have caused his symptoms – possibly sodium or perhaps alcohol from the cooking wine. But he believed MSG was the culprit and coined the term “Chinese Restaurant Syndrome” to describe his ailments.

The journal received many more reports of this alleged syndrome, with symptoms also said to include headaches, dizziness and lightheadedness, tightness of the jaw and chest and back pains. Many letters – debunking the whole idea – were also sent to the journal, and the original letter is now considered a hoax written under a pseudonym (although there was a real Dr. Kwok, a researcher and pediatrician, who died in 2014 and had nothing to do with the letter).

A 1969 study supported the notion that MSG was dangerous. Extremely high doses of MSG were injected directly into the abdomen of newborn mice and resulted in acute neuronal necrosis in several regions of the developing brain, stunted growth and obesity. However, the study was flawed; it didn’t test the effect of MSG as a food ingredient, and the mice were injected with much more MSG than anyone would typically consume in a day. It was also unable to explain why symptoms only occurred in some people, and not others.

However, by the 1980s and 90s, things had changed; it was time to challenge the evidence and determine whether MSG really was unsafe. In 1993, a double-blind, placebo-controlled study failed to find evidence linking Chinese Restaurant Syndrome to MSG. Seventy-one adults received various amounts of MSG or a placebo for 5 days; the results revealed that 86% of participants had no response to the placebo and 85% had no response to MSG treatments.

Further research in 2010 found there was no consistent clinical data to support the existence of Chinese Restaurant Syndrome, or that some individuals may be uniquely sensitive to glutamate. A review of scientific literature in 2019 noted “several methodological flaws in previous research” and concluded that claims linking MSG to an assortment of ailments were unsubstantiated.

Is it safe?

Since the late 1980s, research has focused on the safety of MSG as a food additive. In 1988, a Joint Food and Agricultural Organization of the United Nations (FAO) and World Health Organization (WHO) Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food of the European Commission failed to link MSG with Chinese Restaurant Syndrome, concluding MSG offers no health risk when used as a food additive.

The Scientific Committee for Food of the Commission of the European Communities (SCF) also reviewed the data in 1991 and reached similar conclusions. Around the same time, the US Food and Drug Administration (FDA) tasked the Federation of American Societies for Experimental Biology (FASEB), an independent scientific group, to examine the safety of MSG; their report concluded that MSG is safe and the flavor enhancer is classified as “generally recognized as safe” or GRAS.

“With the exception of some sensitive asthmatics, even high concentrations are harmless and flush from your system in a couple of hours,” says Bixby. “There are currently no regulations requiring food products to state that MSG is included in the item. What you generally see is a product proclaiming to be MSG-free as a positive attribute.”

However, the FDA does require all food containing added MSG to list it (as monosodium glutamate) in their ingredients panel on the packaging. If MSG occurs naturally, as it does in yeast extract and soy extracts, then there is no need to specify that they contain the flavor enhancer.

The key to reducing sodium consumption

MSG is a valuable tool to bring an umami taste to foods, but it could have another benefit: reducing sodium content. An estimated 90% of Americans consume too much sodium in their diet, with over 70% of this coming from commercially processed and restaurant food. Much of this sodium is in the form of sodium chloride – regular table salt – which is used not only to add taste to foods like processed foods such as meats, sauces and seasonings but also to preserve it.

“When we started to study the history of sodium chloride consumption, we could see that the salt was, and still is, the main preservative against deterioration and microorganisms that cause infections and intoxications,” explains Maluly. “It is also a good flavor enhancer, and our tongue usually likes the salty taste. But, over the years, its consumption has increased a lot and, like all substances, it has a limit.”

Too much sodium in the diet can lead to chronic health issues like water retention, kidney disease, stomach cancer, osteoporosis, high blood pressure and an increased risk of heart attack and stroke. The WHO recommends a maximum daily consumption of 5 g of salt for adults, which is equivalent to less than 2 g of sodium per day.

Substituting sodium for alternatives like potassium, calcium or MSG could reduce the amount of sodium in our foods, without compromising on taste. A so-called “Salt Flip” experiment in 2020, asked participants to evaluate different versions of four healthy dishes made with a standard recipe, enhanced with MSG or reduced salt content. The MSG recipes were liked the same or more than the standard recipe and better than the reduced salt version, leading the authors to conclude that MSG could be used to reduce salt consumption without compromising on taste.

Maluly’s work agrees that MSG could be used as a strategy to reduce sodium in processed and homemade foods without affecting the perception of saltiness and, therefore, contributing to the wellness and safety of the population.

“I have been studying food additives for a long time and when I started to study MSG and other flavor enhancers, I was delighted with the capacity of the human being to create different seasonings to add in foods and improve their flavor,” says Maluly. “MSG could be an alternative for adding flavor in food, because the amount of sodium in its composition is very low; while sodium chloride has ~40% of sodium, MSG has ~12%.”

By using MSG as a partial substitute for regular table salt, it’s possible to reduce the sodium content and improve the flavor. It has two-thirds less sodium than regular table salt - and you only need a small amount to elevate the overall flavor.

“MSG has to be used judiciously or your dish will get out of balance. Properly used, it is a safe and effective flavor enhancement that has gotten a bad reputation over the years,” says Bixby. “I keep it on the shelf and use it very sparingly in my cooking. Like any spice or flavor adjunct, there is a proper place and fashion to use MSG that is harmless and improves the food you are preparing.”

To use MSG in a homemade recipe, the suggestion is to use half a teaspoon for every 500 g of foodstuff, like minced meat or rice. Replacing half a teaspoon of sodium with half a teaspoon of MSG could reduce the sodium content by around 37%. By adding glutamates to certain foods, it’s estimated that the American population’s sodium intake could be reduced by approximately 3% overall.

“And, of course, MSG and other flavor enhancers, like yeast extract, fish powder, oyster and soy sauce… all of them could provide umami taste in your recipe,” says Maluly. “If you introduce an equilibrium and flavor in your daily life, you can live better, in all senses.”

MSG a useful partial substitute for salt

A hoax letter in a highly respected journal led to a perfectly safe flavor enhancer being shunned for decades; MSG didn’t deserve its unsavory reputation, but even today people still believe the misleading rumor and misinformation. Thanks to MSG’s widespread use, these same people are likely to consume MSG in both natural and processed foods they eat daily without even realizing they’re consuming the very ingredient they claim to dislike.

And they’d better get used to it as MSG is likely to find its way into many more foods. Research has shown MSG to be a useful partial substitute for salt and could form part of a strategy to reduce the overall consumption of sodium. This once-misunderstood ingredient could be key to improving our health.