Monosodium glutamate (MSG) has been a source of controversy and concern for decades, fueled by anecdotal reports and early, flawed studies. However, modern, well-controlled research has consistently affirmed the safety of this flavor enhancer for the general population. By understanding the scientific consensus and distinguishing it from unfounded myths, consumers can make informed choices about how much MSG is okay to consume.
What is MSG and How is it Metabolized?
MSG is the sodium salt of glutamic acid, an amino acid found naturally in both the human body and a wide variety of foods. These natural sources include tomatoes, parmesan cheese, mushrooms, and meat. Whether glutamate is consumed from added MSG or naturally present in food, the human body metabolizes it in the exact same way. Over 95% of ingested glutamate is used as fuel by the cells lining the gut. This process makes it unlikely that consumed glutamate significantly impacts brain function, as it is largely metabolized before entering general circulation.
The Verdict from Health Authorities
Major health organizations worldwide have evaluated MSG and concluded it is safe for consumption. The FDA classifies it as “Generally Recognized As Safe” (GRAS), and the World Health Organization (WHO) has also endorsed its safety. The European Food Safety Authority (EFSA) established an Acceptable Daily Intake (ADI) of 30 mg per kilogram of body weight per day in 2017. This ADI is based on the highest dose at which no adverse effects were observed in animal studies. For an average 70kg (154-pound) person, this translates to 2,100 mg (or 2.1 grams) per day—an amount well above what most people consume from added MSG. A typical serving of food with added MSG contains less than 0.5 grams.
Comparing Normal Intake vs. Safety Limits
- Average Daily Intake from Added MSG: Around 0.55 grams, significantly lower than the ADI.
- Total Daily Glutamate Intake from Protein: The average adult consumes 10 to 20 grams of glutamate from protein sources daily, showing the body's efficient processing of this amino acid.
- Level for Sensitive Individuals (Without Food): Around 3 grams or more, consumed on an empty stomach, may cause temporary, mild symptoms in a small population of sensitive individuals.
Separating MSG Myths from Scientific Facts
The fear of MSG was largely triggered by a letter published in 1968 that described symptoms experienced after eating Chinese food, coining the term "Chinese Restaurant Syndrome". Since then, scientific evidence has repeatedly debunked this link.
Common Myths Debunked:
- Headaches: Numerous blinded, placebo-controlled studies have failed to prove a link between MSG and headaches. The International Headache Society even removed MSG from its list of triggers in 2018 due to lack of evidence.
- Allergic Reactions: A true allergic reaction to MSG is not supported by scientific evidence. Reported symptoms are typically transient and mild, occurring in a small, self-identified sensitive population at very high doses.
- Obesity: Studies linking MSG to obesity often rely on very high doses administered in animal models. Observational human studies have not found a consistent association between MSG consumption and weight gain when other factors are considered.
Comparison Table: Added vs. Natural Glutamate
| Feature | Added MSG (E621) | Naturally Occurring Glutamate |
|---|---|---|
| Chemical Composition | Monosodium salt of glutamic acid. Chemically identical to natural glutamate. | Free glutamic acid, an amino acid, found in food proteins. |
| Metabolism | Metabolized identically to naturally occurring glutamate by the human body. | Metabolized identically to added MSG by the human body. |
| Typical Intake | Low—less than one gram per day for most people. | Very high—10 to 20 grams per day from foods like meat, cheese, and vegetables. |
| Taste Effect | Enhances savory umami flavor. | Provides savory umami flavor. |
| Primary Source | Fermentation process using carbohydrate sources like sugar beets or corn. | Protein breakdown in whole foods. |
The Role of MSG in Sodium Reduction
Contrary to popular belief, MSG is not high in sodium. It contains about one-third the amount of sodium found in table salt. This property makes MSG a useful tool for reducing overall sodium intake without sacrificing flavor. Replacing a portion of table salt with MSG in recipes can reduce the sodium content by 20% to 40% while maintaining the desired salty and savory taste. This can be a valuable strategy for those seeking to manage their sodium consumption for health reasons, such as high blood pressure.
Who Should Be Cautious?
While MSG is safe for the vast majority of people, a very small number may experience transient, mild symptoms when consuming a high dose (over 3 grams) of MSG, particularly on an empty stomach. This is referred to as "MSG symptom complex". However, these reactions are not life-threatening, do not lead to long-term health issues, and are distinct from a true allergy. If you suspect you are sensitive, the most effective approach is simply to limit or avoid foods with added MSG. It is also important to note that many natural, unprocessed foods are high in glutamate, so complete avoidance is virtually impossible.
Reading Labels for Added MSG
To determine if a food contains added MSG, you can check the ingredient label. In many regions, regulations require that added MSG be explicitly listed as "monosodium glutamate" or "flavor enhancer (621)". However, it is not required to list naturally occurring glutamate present in ingredients like hydrolyzed vegetable protein, yeast extract, or soy sauce, as these are considered inherent to the flavor. Foods that contain naturally occurring glutamate-rich ingredients are also prohibited from claiming "No added MSG". For restaurant or takeaway food, where labeling isn't standard, it's best to ask staff directly about the use of MSG.
Conclusion: Is MSG Safe for You?
For the vast majority of the population, the amount of MSG per day is not a health concern and is well within established safe limits. Extensive scientific research and numerous safety evaluations by global health organizations support its classification as a safe food additive. The fears surrounding MSG are largely based on outdated and flawed studies, as well as myths. For those with a reported sensitivity, avoiding large quantities, especially on an empty stomach, can prevent mild, temporary symptoms. However, eliminating MSG entirely is neither necessary nor realistic, given its natural presence in many common foods. Understanding that your body processes both natural and added glutamate identically can help demystify this flavor-enhancing ingredient and put its consumption into proper perspective.
For more official guidance on MSG, you can consult the FDA's Q&A on Monosodium Glutamate.
