Is MSG Actually Bad for You? The Truth Behind This Controversial Seasoning

Monosodium glutamate, better known as MSG, is a flavor enhancer commonly used in many Asian cuisines, as well as certain processed food products. But its also a naturally occurring compound in some of the healthiest foods, from mushrooms to eggs to tomatoes. The reputation of this flavor-boosting seasoning hasn’t always been stellar—there are many claims that it negatively impacts metabolism and brain health, for example. But a lot of these MSG conceptions are riddled with controversy and inconclusive evidence. Here’s a closer look at the research in order to answer the question: Is MSG actually bad for you?

What Is MSG?

“MSG comes from L-glutamic acid, which is an amino acid,” says Amy Davis, RD, registered dietitian at FRESH Communications. L-glutamine (another name for L-glutamic acid) is not considered to be an essential amino acid, meaning that the body can make it on its own without needing to consume it.

“MSG is naturally present in a variety of different foods, ranging from chicken to broccoli, but it can also be made from fermenting certain starches,” Davis explains. Other foods that naturally contain MSG include meats, seafood, eggs, parmesan and cheddar cheeses, mushrooms, tomatoes, grapes, walnuts, corn, potatoes, and fermented sauces like miso, soy, and fish sauce.

MSG can also be found on its own as a white powder at the grocery store, and used for seasoning recipes. It offers a rich, umami taste, bringing a savory, unctuous, almost meaty flavor to dishes. Additionally, MSG stimulates taste receptors, helping the other flavor notes in a dish really shine.

However, where you’ll most abundantly find MSG in the supermarket is in a range of packaged foods. Just some examples include canned soups, frozen meals, processed meats, certain condiments, and snack foods. “It also may be used in low-sodium seasoning blends since it contains only a third of the amount of sodium as table salt,” Davis adds.

Fast food establishments and some Asian cuisines like Chinese food also frequently employ the use of this taboo seasoning. 

The History of MSG’s Bad Reputation

“MSG has been a controversial ingredient for years,” Davis says. But why?

In the late 1960s, someone going by the name of Robert Ho Man Kwok wrote a letter to the New England Journal of Medicine reporting a list of bizarre and unpleasant symptoms he seemed to experience after eating at a Chinese food restaurant. In this letter he complained of numbness, weakness, and palpitation. While he was unsure whether his symptoms were due to the alcohol, salt, or MSG he’d consumed prior to experiencing these side effects, assumptions were inevitably made that the MSG was to blame. His bout of sickness was soon dubbed “Chinese restaurant syndrome,” and later renamed “MSG symptom complex (MSC).”

The plot twist? Robert Ho Man Kwok is not a real person, and the letter was never intended to be taken seriously. This made-up name was created and assumed by an orthopedic surgeon named Howard Steel, who wrote the now-infamous letter as a complete joke—part of a bet he’d made with another doctor friend at the time, in the 1960s, over whether he could get himself published in the New England Journal of Medicine. What started as a harmless bet and inside joke between peers became a decades-long, often racially-fueled cascade of misinformation about MSG being a toxic substance.

Is MSG Actually Bad for You?

It is true that MSG symptom complex, or MSC, is a real condition, but it’s only a concern for the very few who have a pronounced sensitivity to MSG. “This condition is estimated to affect only about 1% of the population,” Davis says. “It’s characterized by symptoms such as headaches, dizziness, and numbness after consuming MSG.” Other symptoms of MSC may include nausea, tingling, and flushing of the face.

As for the rest of us, the seasoning may not pose such a risk. Over the years, MSG has had a reputation of being tied to metabolic disorders like type 2 diabetes and obesity, neurotoxicity, kidney damage, and reproductive harm. And you can certainly find a handful of studies purporting these side effects, including this 2015 review, this 2018 review, this 2018 article, yet another 2018 study, and this 2021 study.

However, there’s an equally large amount of peer-reviewed evidence that challenges these claims. For example, this 2018 review found MSG not to negatively impact brain function, while a 2016 review found there wasn’t enough evidence to link MSG consumption to headaches. Another 2018 review also found no significant evidence to prove MSG to be neurotoxic. Additionally, MSG’s inclusion in ultra-processed foods and taste enhancement effects (encouraging more consumption) may be to blame for its ties to obesity and other metabolic conditions.

Meanwhile, plenty of studies have found that, on the whole, the evidence citing negative health consequences of MSG is ultimately underwhelming and minimally applicable to human consumption. Just some of these include a 2017 review, a 2019 article, a 2021 review, and a 2022 review. 

Generally, the above papers discuss that many of the studies finding negative health associations with MSG were often:

• Conducted on animals
• Lacked adequate control groups
• Had small sample sizes
• Dosed MSG in levels far exceeding normal human consumption
• In some cases, studied subjects who were injected with MSG, which wouldn’t translate to effects of oral consumption 

A common, final thought across the board was that more evidence is needed to prove any negative outcomes of consuming MSG. “Much of this research is contradictory and done in animals that were fed massive quantities far beyond normal human consumption,” Davis emphasizes.

Furthermore, MSG is generally recognized as safe (GRAS) for consumption by both the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA)—which is historically far more stringent in their safety requirements than the FDA.

Plus, some very healthy food choices like a handful of fruits, veggies, and lean proteins naturally contain MSG and are not linked to any of the negative health consequences that this seasoning has historically been linked to.

Navigating Foods Choice with MSG In Mind

Armed with all of this information, how should you navigate MSG consumption in your everyday life?

“Based on the current evidence, MSG is just as safe to consume as other seasonings and flavorings, consuming MSG in normal amounts should not cause any adverse health effects,” Davis says. (This, of course, excludes those who exhibit MSC symptoms.)

As with any chemical, whether it's sugar, sodium, or MSG, the right way to approach MSG is to consume it in moderation. While you don’t need to take as much care around healthy, natural sources of MSG, be mindful of those ultra-processed foods containing MSG.

Oftentimes, heavily processed foods containing MSG also boast hefty amounts of sodium and added sugar that may contribute to inflammation and certain conditions like high blood pressure. These options tend to be low in health-boosting nutrients like fiber, vitamins, minerals, and plant compounds as well. Because of this, we should try to limit consumption of these foods to a few times per week or fewer.

When trying to determine whether a processed food option contains MSG, look for “monosodium glutamate” on the ingredients list. However, there can be sneaky natural sources of MSG added under the guise of ingredients like yeast extract, soy extracts, hydrolyzed yeast, autolyzed yeast, protein isolate, and hydrolyzed vegetable protein.

The Bottom Line

All in all, MSG has unfairly gotten a bad rap, thanks to racialized misinformation and insufficient research. While some folks are particularly sensitive or averse to the flavoring agent and should avoid it, MSG is naturally found in a whole host of healthy foods that should be embraced on a frequent basis. On the flip side, MSG can also be included in a slew of ultra-processed foods that should generally be enjoyed in moderation.