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A Fresh Look at MSG
By Sarah Garone, NDTR

Mention the controversial flavor enhancer MSG, and many consumers, and some nutrition professionals, will recoil in distaste. MSG has long suffered a negative reputation as the cause of numerous side effects such as headaches, rapid heart rate, asthma attacks, and nausea. Foodie folklore even has associated it with cancer and brain damage. It’s not surprising, then, that many people continue to avoid MSG.

However, as with other food fads, the latest research on MSG reveals that the uproar around its use may be more hype than scientific substance. Armed with up-to-date information, nutrition professionals can set the record straight on exactly how it may or may not affect health.

The History
Although MSG was identified by Japanese chemist Kikunae Ikeda as a flavor component in sea kelp more than 100 years ago, its unsavory reputation didn’t begin to take root until the 1960s. In 1968, Robert Ho Man Kwok, MD, published a letter in the New England Journal of Medicine detailing a mysterious illness he experienced after eating at Chinese restaurants. Kwok speculated that the MSG used in Chinese cooking caused symptoms such as numbness at the base of the neck, palpitations, and weakness. Soon after, a 1969 study in the journal Science found that mice injected with MSG developed brain lesions, obesity, and disrupted endocrine function.

This confluence of personal anecdotes and animal research spurred the concept of the “Chinese restaurant syndrome,” a complex of symptoms theoretically brought on by consuming MSG. Over time, through media coverage and word of mouth, public opinion turned against MSG—and stayed there. Even now, four in 10 Americans report actively avoiding it.

What the Evidence Says
Some research suggests MSG intake in food may cause adverse symptoms and possible harmful health effects in people sensitive to it. A 2018 review in the journal EXCLI highlighted several studies that connected MSG to adverse reactions, from the symptoms of “Chinese restaurant syndrome” to more serious issues such as impaired reproductive function and reduced glucose tolerance.3 However, the majority of this research was conducted on animals, not humans.

As with any other food, some people may have a sensitivity to MSG that causes unpleasant reactions. An MSG sensitivity may present with a temporary episode of sweating, nausea, flushing, headaches, tingling, or numbness.4 But according to Tia Rains, PhD, a Chicago-based food scientist for Ajinomoto, an amino acid research corporation that creates food products that use MSG, the percentage of the population who experiences this is quite low.5

“It’s difficult to identify a specific number,” Rains says. “The findings from placebo-controlled, double-blinded trials show that more often than not, people do not have any response. In the very few people that do, the responses are inconsistent and not reproducible, even at MSG doses 10 times what’s typical in the diet.” While incidence of MSG sensitivity has yet to be determined, some public health authorities estimate that between 1% and 2% of the population may experience the phenomenon.5 In individual cases, a food journal and diet history are likely the best tools to identify MSG sensitivity.

While there’s a low possibility of adverse reactions to MSG, the majority of recent research reveals that this flavor component isn’t cause for concern for most people. No human research has linked MSG consumption with any type of cancer or brain damage. Likewise, a systematic review from 2016 failed to find any correlation between orally consumed MSG and headaches.6 As far back as 2000, the Journal of Nutrition reported that a connection between MSG and asthma couldn’t be established.7 The FDA has categorized MSG as “generally recognized as safe” since 1959, with frequent reviews of its safety in succeeding years.8 The FDA hasn’t set limits around MSG consumption; however, the European Food Safety Authority defines tolerable daily intake as 30 mg/kg of body weight.9

It’s important to remember, too, that MSG is a naturally occurring compound in many whole foods—from tomatoes to walnuts to meats—so people may be consuming much more of it than they realize, likely without issue. “It is tough to keep track of how much MSG someone is consuming,” says Toby Amidor, MS, RD, CDN, FAND, founder of Toby Amidor Nutrition and a Wall Street Journal best-selling cookbook author. “MSG is simply a combination of sodium and glutamate, an amino acid that’s abundant in nature and naturally present in many everyday foods. The body digests the MSG seasoning and glutamates in foods the same way and cannot tell the difference between the two.”

In addition, studies that have shown adverse reactions to MSG often have done so by administering an extremely high-dose bolus, Rains says. But this doesn’t mimic eating in the real world. “Outside of a laboratory setting, MSG is always consumed in the context of other foods and ingredients.”

Potential Benefits of MSG
Far from being an ingredient to fear, for many people, MSG could be a useful ingredient to consume less sodium, since the glutamate in MSG enhances savory flavors within foods. “MSG provides an umami flavor and depth to food,” Amidor says. “Replacing table salt with MSG can help reduce the amount of sodium in a recipe, since MSG contains one-third the amount of sodium compared with table salt.”

Beyond helping those on a sodium-restricted diet, using MSG or an MSG/salt blend in place of table salt may offer a helpful solution for the general public. According to the American Heart Association, 90% of Americans are consuming too much of this micronutrient.10

Last Word
With the evidence for MSG’s safety in the general population, nutrition professionals have the opportunity to share the facts concerning this flavor enhancer. Rather than fear it as a dietary bogeyman, perhaps it’s time to reevaluate MSG and perceive it as a potentially helpful ingredient.

— Sarah Garone, NDTR, is a freelance writer and food blogger based in Mesa, Arizona. Find her sharing nutrition information and healthful recipes at A Love Letter to Food.

1. Olney JW. Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate. Science. 1969;164(3880):719-721.

2. Dewey C. Why Americans still avoid MSG, even though its ‘health effects’ have been debunked. The Washington Post. March 20, 2018. https://www.washingtonpost.com/news/wonk/wp/2018/03/20/why-americans-still-avoid-msg-even-though-its-health-effects-have-been-debunked/. Accessed August 8, 2019.

3. Niaz K, Zaplatic E, Spoor J. Extensive use of monosodium glutamate: a threat to pulic health? EXCLI J.2018;17:273-278.

4. What is MSG? Is it bad for you? The Mayo Clinic website. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/monosodium-glutamate/faq-20058196. Updated March 20, 2018. Accessed August 14, 2019.

5. Food Standards Australia New Zealand. Monosodium glutamate: a safety assessment. http://www.foodstandards.govt.nz/consumer/additives/msg/Documents/MSG%20Technical%20Report.pdf. Accessed August 8, 2019.

6. Obayashi Y, Nagamura Y. Does monosodium glutamate really cause headache? A systematic review of human studies. J Headache Pain. 2016;17:54.

7. Stevenson DD. Monosodium glutamate and asthma. J Nutr. 2000;130(4S Suppl): 1067S-1073S.

8. Questions and answers on monosodium glutamate (MSG). FDA website. https://www.fda.gov/food/food-additives-petitions/questions-and-answers-monosodium-glutamate-msg. Updated January 4, 2018. Accessed August 8, 2019.

9. EFSA review safety of glutamates added to food. European Food Safety Authority website. https://www.efsa.europa.eu/en/press/news/170712. Updated July 12, 2017. Accessed August 14, 2019.

10. 9 out of 10 Americans eat too much sodium infographic. The American Heart Association website. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sodium/9-out-of-10-americans-eat-too-much-sodium-infographic. Accessed August 19, 2019.