Is MSG bad for you? How the food flavoring became among the most scrutinized additives.

MSG in a bottle with yellow and pink lightening bolts around it
MSG is one of the most popular food additives in the world, but is it bad for you? (Getty images; illustrated by Nathalie Cruz)

When you hear the initialism MSG, certain connotations and possible red flags are sure to come to mind.

Discovered in Japan in 1908, MSG — monosodium glutamate — is one of the world's most commonly used food additives. But despite its popularity, MSG has become one of the most controversial flavor enhancers on the market, largely due to misinformation and ethnocentrism.

But this was not always the case. Initially, MSG was a popular ingredient in the kitchens of Americans, with the U.S. at one point being one of the top consumers of MSG globally.

So how and why did the flavor-enhancing crystals go from a spice cabinet staple to one of the most disputed additives in America?

What is MSG?

Again, MSG stands for monosodium glutamate. It's composed of two molecules stuck together: sodium and glutamate. Glutamate is a naturally occurring amino acid used to form proteins in almost all living things, Keri Gans, a registered dietitian nutritionist and author of The Small Change Diet, tells Yahoo Life.

"That's the first thing to realize — it's nothing mysterious," says Gans. "It's actually a naturally occurring amino acid."

And it is everywhere. Karen Ansel, a registered dietitian nutritionist and author of Healing Superfoods for Anti-Aging, tells Yahoo Life that most people eat "about 13 grams of naturally occurring glutamic acid every day from foods like asparagus, walnuts, mushrooms, meat and Parmesan cheese."

When combined with sodium, glutamate also serves another unique and piquant purpose: flavor.

"What's unique about it is that there's a receptor on the tongue that tells the brain that it's tasting umami. And so glutamate is actually an amino acid that is the taste of umami in food," explains Gans.

Umami is considered the "fifth" taste and can be described as a "savory" enrichment, commonly brought out by MSG.

"So we have all the other tastes — the sweet, the sour, salty, bitter — and umami is our fifth taste, and MSG taps into that," says Gans.

MSG was first discovered in Japan by Kikunae Ikeda and made its way to the States around 1930, according to Tia M. Rains, a nutrition scientist and the current vice president of customer engagement and strategic communications for Ajinomoto, a Japanese multinational food and biotechnology corporation and MSG manufacturer.

"In 1909, the Ajinomoto company was launched to bring this tabletop seasoning to the people of Japan," Rains tells Yahoo Life. "And for many decades, around the world, MSG was consumed without issue. So in the '30s and '40s, the U.S. was one of the top three consumers of MSG globally, and no one had an issue with it. It was used in military rations. The product Accent was released in the mid-1940s, again, as a seasoning for food, and it was consumed without issue."

Gans says that MSG was originally used in Asian cultures and is associated with Chinese food in the U.S. "But the truth is, it can be used in anything," she says. "I've added it to my eggs. If you want some flavoring but you want less sodium, I mean, that's it."

The food additive is actually present in a vast array of everyday foods. "MSG is often added to processed foods like soy sauce, instant noodles, canned soup, salad dressing, crackers and chips, hot dogs and deli meats," Ansel points out.

When did attitudes toward MSG change?

Although MSG has been a popular seasoning in food, things soon changed — and it all started with a letter.

"In 1968, a physician wrote a letter to the editor at the New England Journal of Medicine" — called "Chinese-Restaurant Syndrome" — "and talked about his personal account of eating Chinese food within the United States," says Rains. "And in this letter, he mentions that sometimes after eating Chinese food, he notices general weakness and sometimes palpitation and numbness is his outer extremities. And he suggests in this letter that it could be the cooking wine. It could be excessive salt that's used in the food, or it could be the MSG — excessive use of MSG." Rains says the doctor asked "if somebody out there could better understand what he's been feeling when he's eating at these restaurants."

Although the letter apparently turned out to be hoax, the damage was done. Since MSG is largely associated with the flavors found in Asian cuisine, many Chinese restaurants have taken the brunt of MSG-centered judgments since then.

Biases continued to grow in the 1970s after a few scientists conducted experiments that sought to illustrate the supposed harms of MSG. However, some argue the method of testing was flawed.

"They injected really large doses of MSG directly into the abdomen and brains of laboratory rodents," says Rains. "And much like you would find anytime you are overdosing an animal with a particular compound, it made the rats and mice very sick. And so all of those things together all of a sudden started to paint this bad picture about Chinese food and then about MSG — even though there was no scientific evidence in humans, [and] there was no clinical evidence to suggest that there was anything wrong with MSG. But all of those things together caused this vilification of this ingredient."

Is MSG bad for you?

The word sodium typically generates a certain level of concern in the health conscious, which has also played a role in the condemnation of MSG — despite the fact that it contains less sodium than standard table salt.

"If you use MSG, you can actually lower the amount of sodium in a recipe," says Gans. "The sodium content of MSG is about one-third of that in sodium chloride," which is table salt.

Like any other seasoning, too much can be harmful, but MSG is "generally recognized as safe" by the FDA. The organization found no evidence that MSG in food caused symptoms.

The connection between xenophobia, food and "clean eating"

General health misinformation is not the only reason MSG has gotten such a bad rap. Racial biases also play a role.

Referring to an increase in biases starting in the 1960s and '70s, Rains says, "There was a lot of negativity surrounding Asian Americans. It was the Vietnam War — much like we saw with COVID, there was kind of this uptick in Asian hate. That's what was happening in the country at that time. And so you had all these things kind of coming together, where it became very easy to point a finger at Chinese food and start suggesting that there's something inherently unhealthy or wrong with Chinese food and then link it to the MSG."

This has been proliferated by a widespread desire to shun the unknown, says Gans, who argues that an inquisitive mindset may be part of the solution to reducing food-based racial stigmas. "If you don't understand something, ask questions," says Gans.

The promotion of "clean eating" is another culprit in the stigmatization of MSG. Clean eating typically refers to consuming unprocessed and unrefined foods as a healthier way to eat. However, some nutrition experts find this to be tinged with racial microaggressions and can lead to restrictive eating.

"If you look at what people have deemed clean eating, it's usually this Western European dietary pattern," says Rains. "It's not inclusive of other food cultures, and if anything, it puts all Asian cuisine in this bucket of 'dirty,' and I think MSG has been put into that place because of that."

First and foremost, says Gans, "food should be enjoyed. If you worry about every single ingredient that you're putting in your mouth, then trust me, there's no way you're enjoying your food." She adds: "People are worried about every ingredient and developing this all-or-nothing attitude. Striving for perfection in eating can turn into orthorexia," which is an unhealthy focus on healthy eating, often to the detriment to one's well-being.

What is MSG symptom complex?

Formally referred to as "Chinese-restaurant syndrome," MSG symptom complex refers to a collection of symptoms — such as general weakness, headache, muscle tightness and flushing — that only a small subset of people experience after eating food that has MSG. MSG symptom complex is said to affect about 1% of people.

"Anecdotally, I am sure there are some people that might have experienced that effect, the same way that they might be affected by eating another ingredient," says Gans, who notes that adverse reactions to foods are not necessarily MSG-specific.

"Was it just from too much sodium from the soy sauce? Was it all the beer they drank plus the soy sauce? Did they overeat? There are other factors that sometimes are hard to pinpoint and identify as a specific ingredient," Gans points out.

A double-blind, placebo-controlled study found that in people who believe they have a sensitivity to MSG, some may experience symptoms, such as general weakness or headache, when given large doses of MSG taken without food and on an empty stomach — which is not typically how people consume MSG. However, the study showed no persistent or severe effects from MSG ingestion. What's more, when the subjects who believed they had an MSG sensitivity were retested, the results weren't consistent. The researchers also noted that study subjects who appeared to be sensitive to MSG may not have the same reaction when it's administered in food. Other studies have shown that people react similarly to placebos as they do to MSG.

"We try to ensure that people understand that even if they may have those symptoms, the regulatory agencies have said that they are transient and that they are not harmful to health," says Rains.

Ansel agrees, saying that "MSG has a long safety record, so if it doesn't bother you, there's no reason to avoid it. Of course, if you are one of the small number of people who is highly sensitive to MSG, it makes sense to avoid it."

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