Several weeks ago, I wrote an in-depth article on MSG for 75ToGo.com. A summarized version is below. For the full content, including tables and additional interviews and sources, go to www.75togo.com/msg-health-nutrition-guide.
To set the record straight about MSG, I've taken a close look at the large body of scientific research and spoken with the US Food and Drug Administration (FDA) to learn what you need to know about MSG -- what it is, why it's used, and whether or not it's safe.
What is MSG?
Like its name suggests, monosodium glutamate (MSG) is the product of two smaller components: sodium (found, for example, in table salt) and glutamate (an amino acid). Glutamate is naturally abundant in our own bodies and in the foods we eat. It is not inherently harmful, and is vital to a wide range of biological functions. The human body even creates its own glutamate as needed.
Why is MSG added to food?
MSG is used as a "flavor enhancer," meaning it improves the perception of other flavors in a dish. Usage levels are low, usually 0.1-0.8 percent by weight, which is similar to the concentration of free glutamate that naturally occurs in tomatoes or Parmesan cheese.
Other glutamate-rich seasonings, such as yeast extract and hydrolyzed vegetable protein (HVP), can be used to impart umami instead of MSG. Additionally, yeast extracts and HVPs often provide notes of cheese, chicken, or beer. Usually the choice between using MSG and using one of these alternative flavor enhancers is based on:
- flavor profile
- cost (MSG is often the cheapest option, but not always)
- labeling -- pure MSG is unpopular with many consumers
MSG and "Chinese Restaurant Syndrome"
In 1968, a physician named Robert H. M. Kwok wrote a letter to the New England Journal of Medicine describing the numbness, tingling, warmth, and feeling of tightness he suffered 15-60 minutes after eating Chinese food. He called these symptoms "Chinese Restaurant Syndrome."
Due to growing consumer concern, the FDA and Center for Food Safety and Applied Nutrition (CFSAN) commissioned an independent review of all scientific findings on MSG. That study was performed by the Federation of American Societies for Experimental Biology (FASEB) and was published in 1995 as a supplement to The Journal of Nutrition.
FDA Spokeswoman Marianna Naum, Ph.D. had this to say about the results:
The FASEB report did identify temporary and generally mild symptoms that may occur in some individuals after consuming 3 grams of MSG without food. However, to-date, scientists have not been able to consistently trigger these temporary reactions in studies where MSG was provided with food. Based on the available evidence, FDA considers MSG to be safe for use as an ingredient at normally-consumed levels for the general population.
According to the FDA website, "An average adult['s] ... intake of added MSG ... estimates at around 0.55 grams per day." And of course, that's with food.
The FASEB's findings have been largely confirmed by more recent MSG research, including a large multicenter, double-blind, placebo-controlled, multiple challenge test published in 2000. Researchers on this study concluded that:
... large doses of MSG given without food may elicit more symptoms than a placebo in individuals who believe that they react adversely to MSG. However, neither persistent nor serious effects from MSG ingestion are observed, and the responses were not consistent on retesting.
The science continues to support that adverse reactions to MSG consumption are rare, mild, temporary and inconsistent, and generally caused by large doses given without food, even in the most sensitive population. In short, a person would have to consume over five times their typical consumption level and do so without eating any food in order to trigger symptoms. And even then, only sensitive individuals would exhibit a reaction.
Are you sensitive to MSG?
The most reliable studies I found on MSG conclude that adverse reactions (if any) were inconsistent and not repeatable. That is not to say, however, that no one has ever had an adverse reaction to MSG -- just that people who identified as MSG-sensitive didn't consistently and repeatably react to MSG. And until results are repeatable and consistent, they just don't carry any scientific weight.
For some, the anecdotal evidence of a friend's symptoms is enough, but before you blame MSG outright, consider the following possible causes of CRS symptoms:
- You may be sensitive to some part of the food you eat, but not specifically to MSG.
- You may be mildly allergic to something in your food. Mild allergic reactions to the soy or fish common in Chinese food are sometimes misattributed to MSG sensitivity, which is not an allergy.
- You may be sensitive to the high histamine levels present in many Chinese foods, which can sometimes mimic an allergic reaction.
- You have a pre-existing vitamin B6 deficiency, which some researchers have speculated is the true cause of CRS symptoms.
- You may be experiencing referred pain due to irritation of the esophagus.
- You have a true sensitivity to MSG (extremely rare).
If you're experiencing symptoms after eating Chinese food or food containing MSG, your best course of action is to see a doctor, who may then refer you to an allergist, registered dietitian, or other specialist for further testing depending on your symptoms.
Conclusion
So why do people continue to condemn MSG even after 40 years of science have failed to show that eating MSG causes harm? Because once fear is ingrained, it's difficult to completely remove.
Adding to this consumer uncertainty is the fact that the true cause of CRS is still a mystery. Many people are left wondering, "Why do some people feel ill after eating food containing MSG?" Some researchers speculate that the symptoms of CRS are caused by referred pain due to irritation of the esophagus. Others suspect it could involve a Vitamin B6 deficiency or the high histamine levels present in many Chinese foods.
Featured image: [liz west]
Read the full-length article to learn about the discovery and production of MSG.
Read the full-length article to learn about umami as the fifth taste.
Read the full-length article to learn about labeling regulations for MSG and other flavor enhancers.
Read the full-length article to learn about MSG and migraines.
Read the full-length article to learn about MSG and asthma.
Read the full-length article to learn why MSG keeps getting a bad reputation on the internet.
Read the full-length article for advice on your next step.
Notes
1. Medline Plus. Amino Acids. (2013). at http://www.nlm.nih.gov/medlineplus/ency/article/002222.htm 2. Center for Food Safety and Applied Nutrition. Food Additives & Ingredients - Questions and Answers on Monosodium glutamate (MSG). at http://www.fda.gov/food/ingredientspackaginglabeling/foodadditivesingredients/ucm328728.htm 3. Abegaz, E. Interview with Dr. Abegaz of Ajinomoto USA. (2014). 4. Naum, M. Interview with FDA Spokeswoman Marianna Naum, Ph.D. (2014). 5. Burrin, D. G. & Stoll, B. Metabolic fate and function of dietary glutamate in the gut. American Journal of Clinical Nutrition 90, 850S-856S (2009). 6. Marcus, J. B. Unleashing the Power of Umami. Food Technology Volume 63, (2009). 7. Jinap, S. & Hajeb, P. Glutamate. Its applications in food and contribution to health. Appetite 55, 1-10 (2010). 8. Williams, A. N. & Woessner, K. M. Monosodium glutamate 'allergy': menace or myth? Clinical & Experimental Allergy 39, 640-646 (2009). 9. Federation of American Societies for Experimental Biology. Executive Summary from the Report: Analysis of Adverse Reactions to Monosodium Glutamate (MSG). J. Nutr. 125, 2891S-2906S (1995). 10. Kwok, R. H. M. Chinese Restaurant Syndrome. N. Engl. J. Med. 278:796, (Letter to the Editor) (1968). 11. Geha, R. S. et al. Review of Alleged Reaction to Monosodium Glutamate and Outcome of a Multicenter Double-Blind Placebo-Controlled Study. J. Nutr. 130, 1058S-1062S (2000). 12. Folkers, K. et al. The biochemistry of vitamin B6 is basic to the cause of the Chinese restaurant syndrome. Hoppe-Seyler's Z. Physiol. Chem. 365, 405-414 (1984). 13. Kenney, R. A. in Glutamic acid: advances in biochemistry and physiology (ed. Filer, L. J.) 363-373 (Raven Press, 1979). 14. Kenney, R. A. The Chinese Restaurant Syndrome: An anecdote revisited. Food and Chemical Toxicology 24, 351-354 (1986).