Is MSG Bad for You? A 2020 Dr. Review

Here in the United States, there’s a common fear of MSG.  It’s often blamed for a number of disturbing side effects, despite being a common food additive. 

Also known (somewhat offensively) as “Chinese Restaurant Syndrome”, many blame MSG for a slew of symptoms including, headaches, flushing, dry mouth, heart palpitations, and migraines. But where did this idea come from? And does the science actually support it?  

The first association between Chinese Reasutrant Syndrome and MSG seems to stem from a 1968 article published in The New England Journal of Medicine.⁽¹⁾ In it, A doctor anecdotally blamed the MSG used in Chinese restaurants for his heart palpitations. 

Strangely, for years afterward, this supposed syndrome was considered a legitimate diagnosis and became a very popular explanation for certain collections of symptoms.  More recently, it’s become increasingly trendy for food manufactures to use labels stating “no MSG” as a way of assuring consumers that their product is safe. 

The only issue is, there’s no actual scientific evidence of an association between MSG and any of the symptoms mentioned above.  In fact, the FDA recognizes MSG as a Generally Recognized as Safe (GRAS) substance. Before we get too far into the research findings, however, let’s first discuss some of the basics, like what MSG actually is.

What is MSG?

Short for monosodium glutamate, MSG is a seasoning comprised of glutamate and sodium that’s commonly used as a flavor enhancer. Glutamate is an abundant naturally occurring amino acid that can be found in a variety of different foods including tomatoes.  In fact, it can even found in human breast milk.

Glutamate was first discovered to be a flavor enhancer back in the early 1900s by a Japanese researcher named Kikunae Ikeda.⁽²⁾ Ikeda was able to isolate the glutamate found in natural foods and stabilize it using sodium. In this way, MSG became a crystalline substance that resembles salt or sugar. 

Ikeda is also remembered as the first scientist to name a “5th taste”, called umami. The first four tastes are commonly referred to as sweetness, sourness, saltiness, and bitterness. The flavor of MSG is difficult to recreate because it is not really recognized by the other four taste receptors. For a long time, the mere existence of umami was disputed, but it was later found that there are glutamate receptors on the tongue, rendering the idea valid.⁽³⁾

These same glutamate receptors have also been found in our digestive tracts, and a number of studies have actually investigated whether or not the ingestion of MSG can help with digestion.

Interestingly, MSG contains less sodium than common table salt, so it may actually be a better choice to season food with. Though MSG is most commonly known as a food additive in Japanese and Chinese foods, it’s actually pretty common in some kinds of western food as well -- many chefs use MSG in non-Asian dishes to enhances the flavor.

What Symptoms Are Supposedly Linked With MSG?

MSG has been reported to cause headaches, weight gain, dry mouth, heart palpitations, migraines, and even brain damage.⁽⁴⁾ Because glutamic acid functions as a neurotransmitter, the fear was that in large doses, MSG could raise the level of glutamic acid in the brain. This, in turn, was theorized to overstimulate nerve cells. 

The fears surrounding MSG and brain health are largely due to a 1969 study, which showed that when large doses of MSG were injected into newborn mice, they experienced neurological side effects.⁽⁵⁾ However, we know now that ingesting MSG in foods does not raise glutamic acid in the brain -- this is because MSG cannot cross the blood-brain barrier. 

While some of the above-mentioned symptoms were observed when excessive dosages were administered, a 2019 review concluded that at appropriate dosages, there was no credible evidence of an association between MSG and any negative symptoms or side effects.⁽⁶⁾

Does MSG actually cause Headaches(or other symptoms): What Does the Science Say?

Though MSG has become a popular scapegoat, there’s actually very little scientific evidence behind all the negative claims. In the 1990s, the FDA asked a scientific group to conduct an independent study investigating whether or not MSG was really as bad as everyone thought it was. 

At the conclusion of the study, the researchers ultimately failed to find any evidence of an association between MSG and any specific symptom.⁽⁷⁾ Most foods contain less than half a gram of MSG, and the study found that even people who are sensitive to the ingredient would need to ingest nearly 3 grams before experiencing adverse effects.

Another 2016 review published in the Journal of Headache and Pain broke down numerous studies trying to determine a link between MSG and headaches.⁽⁸⁾ At the time, MSG was listed as a causative substance in the International Classification of Headache Disorders, so there was much interest in determining if MSG really caused this issue. 

The review included six studies where the subjects were given MSG in food. Of the six studies evaluated, only one showed a significant association between MSG and headaches -- that one study showed a significant effect only in one female group who were given MSG. 

The paper also breaks down seven studies where the subjects were administered an MSG supplement. Of these seven studies, four showed a significant association between headaches and MSG ingestion. 

However, the researchers found that the dosages that were administered in the studies were much higher than the amount of MSG that’s found in food products.  They ultimately concluded that in order for a significant association to occur, researchers had to give subjects far more MSG than what they’d be able to obtain from food sources alone.   Since the publishing of these findings, the International Headache Society has since removed MSG from their list of headache triggers. 

Due to the sizeable body of evidence dispelling any association between MSG and adverse health effects, The FDA has categorized MSG as a “generally recognized as safe” (GRAS) substance -- that’s the same rating it gives to other commonly used food additives like sugar and baking powder.  

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Should You Consume MSG?

To date, research has failed to find any link between MSG ingestion and adverse health outcomes when appropriate dosages were administered.  The amount of MSG that would need to be ingested to cause adverse effects, is much higher than any person would be able to consume as part of a traditional meal.  The only studies demonstrating significant adverse effects seem to have involved MSG supplements containing dosages far beyond what’s normally found in food.   

With that being said, it doesn’t necessarily mean that you should gorge out on MSG-rich foods.  Like with many food additives and flavor enhancers, MSG is often used in highly processed foods, which should only be eaten in moderation on any healthy and well-balanced diet -- consuming these foods regularly presents a number of health concerns. 

The bottom line is that there’s no scientifically proven correlation between MSG and any of the reported symptoms. As with any food (or food additive) though, it’s important to pay attention to the way your body feels after eating. You should, of course, avoid anything that makes you feel unwell. However, as far as the science is concerned, it’s unnecessary to avoid MSG, especially if you enjoy the taste.

• References
  1. “A Racist Little Hat: The MSG Debate and American Culture”Germain, T. CURJ. May. 2015.
  2. “ Metabotropic glutamate receptor type 1 in taste tissuee”Appaiah, M.K. Ensuring Global Food Safety. May. 2010.
  3. “ Metabotropic glutamate receptor type 1 in taste tissue”San Gabriel, A., Maekawa, T., Unetama, H., Torii, K. The American Journal of Clinical Nutrition. Sep. 2009.
  4. “Metabotropic glutamate receptor type 1 in taste tissue”San Gabriel, A., Maekawa, T., Unetama, H., Torii, K. The American Journal of Clinical Nutrition. Sep. 2009.
  5. “Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate.”Olney, J.W. Science. May. 1969.
  6. “A review of the alleged health hazards of monosodium glutamate”Zanfirescu, A., Ungurianu, A., Tsatsakis, A.M., Nitulescu, G.M., Kouretas, D., Veskoukis, A., Tsoukalas, D., Engin, A.B., Aschner, M., Margina, D. Comprehensive Reviews in Food Science and Food Safety. May. 2019.
  7. “Questions and Answers on Monosodium glutamate (MSG)”U.S. Food and Drug Administration. Apr. 2018.
  8. “Does monosodium glutamate really cause headache? : a systematic review of human studies”Kobayashi, Y., Nagamura, Y. May. 2016.