Understanding MSG: Myths and Facts on this Controversial Food Additive

It’s pervasive. You can find it in Kung Pao Chicken, Ramen, Instant Noodles, Fried Chicken and in most Asian dishes across Beijing and China, be they dine-in and delivery. With an abundance of dietary choices, should we be worried about food flavoring?  Whether you’re on a personal health journey or your friends or family have dietary restrictions, this article delves into the properties of monosodium glutamate (MSG) and salt, their health implications and also provides vocabulary when ordering in Chinese.

Making Foods Delicious

It was Japanese chemist Dr. Kikunae Ikeda who noticed the similarity in flavor between his wife’s kelp soup and the flavors of tomatoes, asparagus, meat and cheese that he’d sampled while studying in Germany (Umami 2024). He then isolated the chemical compound glutamate from the rich seaweed and fish flake broth. The year was 1908, and Dr. Ikeda made two achievements.

First, he had identified the savory flavor in the broth and coined it “umami”. Second, his patent on synthesizing this naturally occurring compound was approved in 1909, making MSG an immediate success in his Japanese production company AJI-NO-MOTO and decades later worldwide (BBC 2019). Posthumously, Dr. Ikeda is recognized as one of the Ten Japanese Great Inventors by the Japan Patent Office for his flavor enhancing condiment (Bafta 2024). Today, AJI-NO-MOTO exists as a 30,000+ employee global corporation.

MSG Symptom Complex (MSC)

A letter purportedly penned in 1968 by Dr. Robert Ho Man Kwok of Maryland to the New England Journal of Medicine (NEJM) with the headline “Chinese-Restaurant Syndrome” outlined symptoms of “numbness in the back of the neck, gradually radiating to both arms and the back, general weakness, and palpitation”. Dr. Kwok postulated MSG, sodium or cooking wine as the culprit (Colgate 2020). The letter, along with a flurry of responses from physicians, thrust MSG into the public scrutiny spotlight, resulting in decades of scientific studies on what’s today termed MSG Symptom Complex (Science History Institute 2024).

The letter’s headline, “Chinese-Restaurant Syndrome”, sparked a wave of prejudice against Chinese cuisine mainly in the USA, with patrons being advised that New York York and Southern California are geographically risky for dining, while locations such as Hawaii and London are safe (Science History Institute 2024). This stigma attached to MSG and, by extension, Chinese food, persisted for decades despite numerous scientific studies failing to find a definitive link between MSG and the reported symptoms.  Despite the backlash, Chinese food is the most popular cuisine for Americans today (QA 2022).

In a bizarre twist in 2018, after Colgate University professor Jennifer Lemesurier published an article on the 1968 letter, alumnus Dr. Howard Steel contacted the author to make several bold claims: first, that the letter was the result of a USD 10 bet between him and a fellow classmate to see who could get published in NEJM; and second, that Dr. Kwok was nothing more than a fictitious name he created to get the letter published (Colgate 2020).

Controversy ensued yet again when Dr. Robert Ho Man Kwok’s children and former colleagues came forward to debunk this accusation by Dr. Steel. Unfortunately, Dr. Kwok (1933-2014) and Dr. Steel (1921-2018) have both passed, but Steel’s daughter Anna commented on the hoax, saying that her father “liked to prank people” (This American Life 2019). Listen to the Podcast on Steel’s prank: https://www.thisamericanlife.org/668/the-long-fuse

Despite past controversy, the American Food and Drug Administration (FDA) considers MSG a “generally recognized as safe” (GRAS) food additive (FDA 2012). The MSG System Complex (MSC) first publicized by Dr. Kwok affects only 1 percent of the general population (Healthline 2023). Symptoms of MSC are generally mild and short-lived (Mayo Clinic 2022), and include:

• Flushing
• Headache
• Muscle aches
• Numbness, burning in or around the mouth
• Heart fluttering
• Tingling
• Drowsiness

MSG VS. Salt: Compared

MSG is a compound glutamate and sodium ions, with 12 percent of the ions from sodium. Salt (NaCL), however, has a 1:1 ratio of sodium ions. MSG simply has less sodium than salt. For MSG, the amount of sodium is 12.28 g/100 g, and this is 1/3 of the sodium when compared to NaCl (39.34 g/100 g) (NIH 2017). For this reason, MSG is added to low sodium soups, meats and prepackaged foods as a salt substitute.

According to the FDA, the maximum average daily intake (ADI) of MSG is set at 30 mg/KG of body weight (FDA 2012). For sodium, however, ADI recommendations vary. The World Health Organization suggests a limit of 2,000 mg per day, while the American Heart Association recommends no more than 2,300 mg per day, moving toward an ideal limit of no more than 1,500 mg per day for most adults (NY Times 2024).

Animal Testing with MSG and Salt

Numerous tests have been conducted on rats on MSG toxicity, all inconclusive in their link to human harm due to differences in biology, testing methods or lack of human studies to confirm results (NIH 2019). For example, a 2023 study on fetal development of pregnant rats concluded MSG causes low birthweight and skeletal anomalies, but these rats were force fed 3 g/KG of MSG in the low dose group, the equivalent of 1,000 times the daily dose for humans (Springer 2023).
 
The effects of salt consumption on humans predated that of laboratory trials, the first being a 1904 clinical study of a salt-free diet reducing the blood pressure (BP) of hypertension participants. In the 1960’s, selective breeding of salt-sensitive and salt-resistant rats given high salt found increased BP in salt-sensitive rats (Hypertension 2023). Humans are not defined this narrowly, but nevertheless, the relationship between salt and those with sensitivity was successfully demonstrated.

Even though MSG is considered safe in foods, if you’ve experienced MSG Symptom Complex in the past, it’s best to avoid it if you’re pregnant. It’s also wise to keep your sodium below the recommended 2,300 mg per day for adults, which may involve avoiding certain fast foods, frozen meals, canned foods and salty snacks (Healthline 2021).

Conclusion

Ordering MSG-Free: If your workplace has a canteen, you’re in luck. Simply request your meal without MSG. For restaurants with set recipes, this may prove trickier, but you can still try these phrases when ordering:

• No MSG: 不要味精 (Bù yào wèi jīng)
• No Salt:   不要放盐 (Bù yào fàng yán)

Consult with a healthcare provider for dietary advice. Although there’s no test for intolerance to MSG, intolerance testing does exist for a variety of allergens. Furthermore, as sodium is an electrolyte, a blood panel may be performed to determine chemical imbalances which may be caused by your diet.

Ever have a reaction to MSG? Sound off in the comments below!

Sources:
(1) https://www.healthline.com/nutrition/msg-good-or-bad, (2) https://www.batfa.com/greatjapanese.html, (3) https://news.colgate.edu/magazine/2019/02/06/the-strange-case-of-dr-ho-man-kwok/, (4) https://www.sciencehistory.org/stories/magazine/the-rotten-science-behind-the-msg-scare/, (5) https://www.umamiinfo.com/ikedakikunae/, (6) https://www.bbc.com/future/article/20190503-the-mystery-taste-that-always-eluded-us, (7) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5694874/
(8) https://www.fda.gov/food/food-additives-petitions/questions-and-answers-monosodium-glutamate-msg, (9) https://www.nytimes.com/2024/03/19/well/eat/sodium-salt-diet.html, (10) https://www.ahajournals.org/doi/full/10.1161/HYPERTENSIONAHA.123.17959, (11) https://www.healthline.com/health/pregnancy/msg-pregnancy#reasons-to-avoid
(12) https://medlineplus.gov/ency/article/001126.htm, (13) https://link.springer.com/article/10.1007/s11356-023-25661-x,
(14) https://www.momswhothink.com/msg-vs-salt/

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Images: Joshua Hiller, University of Virginia Health System