Mariel Tishma
Chicago, Illinois, United States

 

A Chinese Food Storefront in New York, NY. Photo by Jkusachi. June 2019. Via Wikimedia. CC BY-SA 4.0.

Monosodium glutamate’s bad reputation started with one letter to the New England Journal of Medicine. From there, the truth was confused by misinformation and prejudice.

Dr. Robert Ho Man Kwok wrote to NEJM in April of 1968, sharing his observation that after eating at American Chinese restaurants he experienced “numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitation.” Kwok was a Chinese immigrant, and he made it clear that the syndrome, if it was a syndrome at all, only occurred when he ate in American Chinese restaurants. He suggested several possible culprits for his symptoms, including monosodium glutamate (MSG), but only MSG got stuck with the blame.¹

In response, readers sent dozens of personal accounts of discomfort after eating out. The list of symptoms rapidly expanded, as did the number of suspect cuisines. Any discomfort after eating at a restaurant perceived as “oriental” or “exotic” became an occurrence of “Chinese restaurant syndrome.”² Some of these letters may have been little more than poor taste jokes based on prejudice about Asian cuisine and culture, not meant as serious commentary.³ Early studies with sample sizes as small as two tested reactivity to MSG.⁴ Popular media got involved and eventually the New York Times published a story on the “syndrome,” as did the Chicago Tribune.^5,6 Anecdote became scientific fact.⁷ MSG was dangerous.

With that in mind, it is important to understand what MSG actually is. In its most basic form, MSG is a salt made from glutamic acid. It is similar to glutamate, the naturally produced salt of glutamic acid. Glutamate is present in many foods, including tomatoes and cheese,⁸ and may be associated with proteins as an evolutionary sensory marker of nutritious food.⁹ The glutamate in food and added MSG are digested in the same way. Glutamic acid is naturally present in the body, and even human breast milk contains glutamate.^10,11

Kikunae Ikeda, professor of physical chemistry at the University of Tokyo, noted the unique savory flavor of seaweed broth and believed it was distinct from salt. He first extracted MSG from seaweed broth in 1909. His distillation of MSG led to both the commercial production of the salt and a new, fifth basic taste called umami.¹²

MSG was initially marketed to Japanese housewives, especially those who desired a westernized lifestyle. It spread throughout east Asia and eventually became globally available. From the mid-1930s until 1941 the US purchased more MSG than any other country outside of Japan and Taiwan. It was primarily used in food manufacturing, enhancing the flavor of pre-packaged foods like Campbell’s soup.¹³ By 1969 about 58 million pounds of MSG were being produced in the US every year.¹⁴

After Dr. Kwok’s letter, the use of MSG came into question.

Theories arose, trying to explain the exact way MSG caused harm. Some believed that MSG affected glutamate receptors in the brain and altered neurotransmitters.¹⁵ Others believed that MSG was no longer natural—that it had been altered during production and was toxic.¹⁶ More studies were done and identified three main areas of concern: “Chinese restaurant syndrome,” neurological damage, and MSG as an asthma trigger.

One study found that young rats injected with MSG developed brain lesions. In adulthood, these rats had stunted growth, and the females were infertile.¹⁷ The study author worried that the same effects might occur in children whose mothers had consumed MSG while pregnant.¹⁸ Also of concern was the relationship between MSG and asthma. One report presented two patients experiencing asthma attacks twelve hours after eating in a Chinese restaurant. A small study attempted to replicate those results and found 14 of 32 participants reacted to MSG within twelve hours.¹⁹

However, with more rigorous tests and modern data, these early studies have been refuted. Many had small sample sizes, poor methodology, or tested MSG under conditions that did not reflect everyday life.

The presence of food impacts the way MSG is digested. Studies where participants consumed MSG on an empty stomach or where MSG was administered via a non-food route like an injection are more likely to induce a reaction and do not reflect real-world conditions.²⁰ At high concentrations MSG makes food taste worse, limiting the amount people will eat.^21,22 Studies that used these high dosages in one meal also likely do not reflect real-world conditions.

While testing the neurological effects of MSG, researchers noted that when MSG was administered to young mice with food, even at high concentrations, no lesions occurred. When fed small amounts of MSG over long periods mice did not produce lesions, even across multiple generations. In nonhuman primates, even incredibly high glutamate plasma concentrations did not produce lesions. In humans, even when consumed daily MSG did not push plasma glutamate levels to a concentration that would cause harm.²³ Human infants process MSG at the same rate as adults.²⁴ MSG is therefore unlikely to cause neurological damage to humans, including human infants.

The initial study connecting MSG to asthma had a number of flaws. Participants were primarily individuals with unstable and uncontrolled asthma who were more likely to have an attack triggered by other factors. It also discontinued the use of medication that regulated asthma during challenge days but not during placebo days. This made participants much more vulnerable when MSG was administered. Four additional studies with more rigorous guidelines have attempted to replicate the results, but none resulted in an asthma attack after eating MSG.²⁵

In the case of “Chinese restaurant syndrome,” studies have failed to decisively prove that MSG causes symptoms, even when participants included those who felt they were reactive to MSG.²⁶ As Dr. Kwok suggested in his initial letter, another factor may be to blame. Salt is a potential culprit, as a high amount of sodium is present in restaurant meals of any kind.²⁷

Because of the low risk when consumed under normal conditions, many food safety and health organizations have designated MSG safe. The FDA examined MSG with the Federation of American Societies for Experimental Biology (FASEB) in 1995 and concluded MSG is safe.^28,29 The Food and Agriculture Organization of the UN (FAO) and the World Health Organization gathered a committee on food additives who studied MSG in 1971, 1974, and 1987 and concluded it was safe each time.³⁰ The Scientific Committee for Food (SCF) evaluated MSG in 1991 and agreed it was safe.³¹ As late as 2017 MSG was studied and designated safe with a daily intake of 30 mg per kilogram of body weight per day.³²

The FDA has agreed that there may be individuals who are reactive to MSG after consuming more than three grams without food.^33,34 However, most of the symptoms are mild and subside after a few hours. Additionally, as with other food allergens like gluten, the FDA and other food regulation groups have labeling requirements for MSG, allowing those who are sensitive to avoid it should they choose to.

Of course, agreement on MSG’s safety is not universal. In 2018, Pakistan’s Punjab Food Authority banned MSG.³⁵ MSG is no longer front-page news but every few years articles (including this one) return, assuring people that MSG is safe to eat. Why is the fear of this one compound so deeply ingrained?

First is increased attention to food labeling and safety.³⁶ Opposition to synthetic food additives of any kind was widespread at the time of Kwok’s letter, and the public was fiercely fighting for more clear food labels from the FDA.³⁷ This same attention remains a factor today. A larger part of the issue is rooted in racial prejudice.

Even before MSG, American culture designated Asian food as dirty, exotic, or deviant. As far back as Chinese migration to California in the 1850s and 60s, media portrayed Chinese immigrants eating rats or dogs. “Chinese restaurant syndrome” became an extension of that prejudice, with foods containing MSG seen as dirty and those without as clean. Many American and European foods contain glutamate, and many commercialized American foods contain MSG, but only “exotic” or “ethnic” foods like Chinese foods have a syndrome. In another example, the New York City Health Department issued warnings about excess MSG in 1969, but only to Chinese food manufacturers and restaurants.³⁸

The “syndrome” is primarily a Western problem—Asian countries with high MSG usage do not report symptoms.³⁹ It is possible that “Chinese restaurant syndrome,” unable to break free of the intertwined prejudice and fear of unclean food, has become a cultural syndrome. Cultural syndromes take many forms. One example comes from Ecuador—mal de ojo: fever, diarrhea, or even death in children after receiving a malicious stare.⁴⁰ The symptoms in these cultural syndromes are real, but the cause is misplaced. The same may be true for MSG. Those who are sensitive are experiencing something, but the correct cause has not been identified. Continuing to blame MSG prevents science from finding that cause.

It is time to issue MSG a clean bill of health.

 

NOTES

1. Ian Mosby, “‘That Won-Ton Soup Headache’: The Chinese Restaurant Syndrome, MSG and the Making of American Food, 1968–1980,” Social History of Medicine vol. 22 no. 1 (February, 2009): 135, https://doi.org/10.1093/shm/hkn098.
2. Ibid. 136.
3. Jennifer L. LeMesurier, “Uptaking Race: Genre, MSG, and Chinese Dinner,” Poroi vol. 12 no. 2 (February 2017): 2, https://doi.org/10.13008/2151-2957.1253
4. Herbert H. Schaumburg, Robert Byck, Robert Gerstl, and Jan H. Mashman, “Monosodium L-Glutamate: Its Pharmacology and Role in the Chinese Restaurant Syndrome,” Science vol. 163 no. 3869 (Feb. 1969): 826, https://www.jstor.org/stable/1726504
5. Ian Mosby, “‘That Won-Ton Soup Headache’,” 137.
6. Anna Maria Barry-Jester, “How MSG Got A Bad Rap: Flawed Science And Xenophobia,” FiveThirtyEight, January 8, 2016 https://fivethirtyeight.com/features/how-msg-got-a-bad-rap-flawed-science-and-xenophobia/.
7. Jennifer L. LeMesurier, “Uptaking Race: Genre, MSG, and Chinese Dinner,” 2.
8. “Questions and Answers on Monosodium glutamate (MSG),” US Food and Drug Administration – FDA, Last Updated January, 4, 2018, First Published November 19, 2012, https://www.fda.gov/food/food-additives-petitions/questions-and-answers-monosodium-glutamate-msg.
9. Kikunae Ikeda, translated by Yoko Ogiwara and Yuzo Ninomiya, “New Seasonings,” Chemical Senses vol. 27 no. 9 (Nov. 2002): 849, https://doi.org/10.1093/chemse/27.9.847.
10. “Questions and Answers on Monosodium glutamate (MSG),” US Food and Drug Administration – FDA.
11. Kenzo Kurihara, “Glutamate: from discovery as a food flavor to role as a basic taste (umami),” The American Journal of Clinical Nutrition vol. 90 no. 3 (September 2): 721S, https://doi.org/10.3945/ajcn.2009.27462D.
12. Ibid, 719S.
13. Jordan Sand, “A Short History of MSG: Good Science, Bad Science, and Taste Cultures,” Gastronomica vol. 5 no. 4 (November, 2005): 40-43, https://doi.org/10.1525/GFC.2005.5.4.38.
14. Ian Mosby, “‘That Won-Ton Soup Headache’,” 139.
15. John W. Olney, “Brain Lesions, Obesity, and Other Disturbances in Mice Treated with Monosodium Glutamate,” Science vol. 164 no. 3880 (May 1969): 719, DOI: 10.1126/science.164.3880.719.
16. James Wong, “The Truth about MSG,” New Scientist vol. 249, no. 3323 (February 27, 2021): 22. https://search-ebscohost-com.chipublib.idm.oclc.org/login.aspx?direct=true&db=f6h&AN=148952471&site=ehost-live&scope=site.
17. John W. Olney, “Brain Lesions, Obesity, and Other Disturbances in Mice,” 720.
18. John D. Fernstorm, “Monosodium Glutamate in the Diet Does Not Raise Brain Glutamate Concentrations or Disrupt Brain Functions,” Annals of Nutrition & Metabolism suppl 5 (December, 2018): 44, https://doi.org/10.1159/000494782.
19. Donald D. Stevenson, “Monosodium Glutamate and Asthma,” The Journal of Nutrition vol. 130 no. 4 (April 2000): 1067S-1068S, https://doi.org/10.1093/jn/130.4.1067S
20. Ronald Walker and John R Lupien, “The Safety Evaluation of Monosodium Glutamate,” The Journal of Nutrition vol. 130 no. 4 (April 2000): 1051S-1052S, https://doi.org/10.1093/jn/130.4.1049S.
21. Patricia J. Taliaferro, “Monosodium Glutamate and the Chinese Restaurant Syndrome: A review of food additive safety,” Journal of Environmental Health vol. 57 no. 10 (June 1995): 8, https://www.jstor.org/stable/44536821
22. John D. Fernstorm, “Monosodium Glutamate in the Diet” 50-51.
23. Ibid.45-50
24. Ronald Walker and John R Lupien, “Safety Evaluation,” 1051S.
25. Donald D. Stevenson, “Monosodium Glutamate and Asthma,” 1068S, 1073S.
26. Ronald Walker and John R Lupien, “Safety Evaluation,” 1051S.
27. S J Smith, et al., “A new or old Chinese restaurant syndrome?” British Medical Journal (Clinical Research Edition) vol. 285 no. 6349 (Oct. 1982): 1205, doi:10.1136/bmj.285.6349.1205-a.
28. Ronald Walker and John R Lupien, “Safety Evaluation,” 1050S.
29. “Questions and Answers on Monosodium glutamate (MSG),” US Food and Drug Administration – FDA.
30. Yoko Obayashi and Yoichi Nagamura, “Does monosodium glutamate really cause headache? : a systematic review of human studies,” The Journal of Headache and Pain vol. 17 no. 54 (2016): 1, doi:10.1186/s10194-016-0639-4.
31. Ronald Walker and John R Lupien, “Safety Evaluation,” 1050S.
32. Anca Zanfirescu, et al., “A Review of the Alleged Health Hazards of Monosodium Glutamate,” Comprehensive Reviews in Food Science and Food Safety vol. 18 (May 2019): 1112, https://doi.org/10.1111/1541-4337.12448 I.
33. Ronald Walker and John R Lupien, “Safety Evaluation,” 1051S.
34. “Questions and Answers on Monosodium glutamate (MSG),” US Food and Drug Administration – FDA.
35. Saifullah Cheema, “Punjab Food Authority bans Chinese salt after scientific panel finds it hazardous for health,” DAWN Media Group, January 15, 2018, https://www.dawn.com/news/1383111/punjab-food-authority-bans-chinese-salt-after-scientific-panel-finds-it-hazardous-for-health.
36. Jordan Sand, “A Short History of MSG,” 44.
37. Ian Mosby, “‘That Won-Ton Soup Headache’,”134.
38. Ibid, 134-135, 144-145.
39. Alex Renton, “If MSG is so bad for you, why doesn’t everyone in Asia have a headache?” The Observer Food, The Guardian, July 10, 2005, https://www.theguardian.com/lifeandstyle/2005/jul/10/foodanddrink.features3.
40. James Wong, “The Truth about MSG,” 22.

 

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MARIEL TISHMA is an Assistant Editor at Hektoen International. She has been published in Hektoen International, Bloodbond, Argot Magazine, Syntax and Salt, and others. She graduated from Columbia College Chicago with a BA in creative writing and a minor in biology. Learn more at marieltishma.com.

 

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