What is MSG?
Monosodium glutamate, or MSG, is the sodium salt of glutamic acid, an amino acid found naturally in many foods. Glutamate is essential for many bodily functions, including acting as a neurotransmitter in the brain. The human body treats glutamate from MSG in the same way as glutamate found in foods like tomatoes, mushrooms, and cheese. It is widely known for delivering the savory taste sensation known as 'umami,' which is one of the five basic tastes alongside sweet, sour, salty, and bitter.
MSG became a subject of controversy in the late 1960s following a letter to the New England Journal of Medicine that described symptoms experienced after eating Chinese food. This led to the creation of the now-discredited term 'Chinese Restaurant Syndrome,' which was later renamed 'MSG symptom complex'. Since then, numerous studies have explored the link between MSG consumption and reported adverse effects, with modern research debunking many of the initial fears.
The Science Behind MSG’s Effects
For the vast majority of people, MSG is a harmless food additive. The FDA classifies MSG as 'generally recognized as safe,' a designation also applied to other common ingredients like salt and sugar. The average daily intake of added MSG in the United States is around 0.55 grams, far below the high doses (3 grams or more consumed without food) that have triggered mild, temporary reactions in sensitive individuals in some studies. The notion that MSG is an excitotoxin that causes widespread brain damage has also been widely refuted by scientific evidence, with studies showing that MSG does not easily cross the blood-brain barrier.
However, a small subset of the population (less than 1%) may be particularly sensitive to MSG. These individuals may experience a collection of mild, temporary symptoms, which are not considered a true allergic reaction.
Commonly reported symptoms of MSG sensitivity include:
- Headache or facial pressure
- Sweating or flushing
- Numbness, tingling, or burning in the face, neck, and chest
- Rapid heartbeats (palpitations)
- Nausea
- Drowsiness
These symptoms typically appear within an hour or two of consuming MSG and generally resolve on their own within a few hours. More severe, potentially life-threatening reactions like chest pain, difficulty breathing, or throat swelling are rare and warrant immediate medical attention, though they are not conclusively linked to MSG itself.
The Role of MSG in Modern Food
Beyond its flavor-enhancing properties, MSG offers a practical advantage in food production. As it contains about one-third the amount of sodium as table salt, it can be used to help reduce the overall sodium content of a dish without sacrificing flavor. This is particularly useful in processed foods, canned goods, and seasonings where manufacturers are often seeking to create healthier, lower-sodium products.
Comparison: Natural Glutamate vs. Added MSG
All glutamate, whether naturally occurring in foods like tomatoes and parmesan cheese or added as MSG, is metabolized by the body in the exact same way. The key difference is often the context in which it's consumed.
| Feature | Naturally Occurring Glutamate | Added MSG |
|---|---|---|
| Source | Found in whole, unprocessed foods like aged cheese, cured meats, tomatoes, and mushrooms. | Produced through fermentation of starch, sugar beets, or molasses. |
| Usage | Released slowly as food is cooked, aged, or fermented. | Added as a concentrated, pure seasoning. |
| Health Perception | Generally viewed as healthy and nutritious, part of a balanced diet. | Has faced significant controversy and negative public perception over the years. |
| Body's Reaction | Metabolized identically to added MSG by the human body. | Metabolized identically to naturally occurring glutamate by the human body. |
Should you avoid MSG?
For the vast majority of people, there is no scientific reason to avoid MSG. However, some individuals choose to limit it due to personal experiences of sensitivity or a desire to reduce their intake of highly processed foods, where MSG is often found. If you suspect you may be sensitive, the best approach is to monitor your reactions and avoid foods that seem to trigger symptoms. Keep in mind that many processed and convenience foods contain not only MSG but also other refined ingredients and high amounts of sodium and fat, which could be the true source of your discomfort.
Conclusion
How does MSG make you feel? For most, it simply enhances the savory, umami flavor of food, adding depth and deliciousness. While its controversial past continues to influence public opinion, decades of scientific research confirm that MSG is safe for general consumption. A small number of individuals may experience mild, short-term symptoms that are part of the 'MSG symptom complex,' but these are not life-threatening and usually occur only with very large doses. If you are concerned about MSG, paying attention to your body's reactions and reducing processed food intake can be a helpful strategy. The lingering misconception surrounding MSG has more to do with poorly conducted early studies and societal anxieties than with conclusive scientific evidence.
For more information on the FDA's stance on MSG and food additives, visit the FDA's official Q&A page.
