What is unsafe about MSG?: Separating Fact from Fiction in Your Nutrition Diet

November 10, 2025 •

4 min read

According to regulatory bodies like the FDA, MSG is “generally recognized as safe” for consumption by the general population. This contrasts sharply with its controversial reputation, raising the question: What is unsafe about MSG and why is its safety so widely debated?

Quick Summary

Decades of research have shown that the flavor enhancer monosodium glutamate is safe for most people, though a small percentage may experience mild, short-term symptoms at high doses. The negative perception stems from historical misinformation and often confuses MSG with the high sodium and fat content of processed foods.

Key Points

Not a True Allergy: MSG sensitivity, known as MSG Symptom Complex (MSC), is a mild intolerance in a very small portion of the population, not a true immune-system-based allergy.
Requires High Doses: Negative reactions to MSG typically only occur in sensitive individuals after consuming very large amounts (over 3 grams) on an empty stomach, which is far beyond typical dietary intake.
Metabolized Like Natural Glutamate: The body processes glutamate from added MSG identically to the glutamate found naturally in foods like cheese and tomatoes.
Misinformation and Bias: The widespread fear of MSG originated from a poorly documented letter and subsequent biased studies in the 1960s, contributing to xenophobic myths.
Safety Approved by Experts: Major health organizations, including the FDA and WHO, classify MSG as 'Generally Recognized as Safe' (GRAS) based on decades of research.
The Real Culprit is Processed Foods: MSG is often found in highly processed foods, and the side effects some attribute to MSG are more likely caused by the high sodium, fat, or other ingredients in those products.

Debunking the Myth: The Origins of the MSG Controversy

The controversy surrounding monosodium glutamate (MSG) can be traced back to 1968, when a letter was published in the New England Journal of Medicine from a doctor describing symptoms he experienced after eating Chinese food. He speculated that potential culprits were either cooking wine, sodium, or MSG. This single letter, lacking scientific rigor, led to the creation of the term “Chinese Restaurant Syndrome” (CRS), sparking decades of misinformation and xenophobic attitudes towards Chinese cuisine.

Subsequent early studies, attempting to prove MSG's toxicity, were later found to be flawed due to poor methodology, small sample sizes, and the use of unnaturally high doses, often administered via injections rather than oral consumption. This created a lingering stigma, despite later, more robust research providing a different picture.

The Scientific Consensus: A Generally Safe Food Additive

Modern regulatory and scientific bodies have concluded that MSG is safe for consumption within normal dietary limits. The U.S. Food and Drug Administration (FDA) has classified MSG as “Generally Recognized as Safe” (GRAS) since 1958, a position reinforced by multiple reviews. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Food Safety Authority (EFSA) have also affirmed its safety.

What About the MSG Symptom Complex?

While MSG is safe for most, a very small percentage of the population (less than 1%) may have a sensitivity that results in mild, short-term reactions, now called the MSG Symptom Complex (MSC). These are not allergic reactions involving an immune response, but rather an intolerance. Symptoms may include:

Headaches
Flushing or sweating
Numbness or tingling
Facial pressure
Chest pain
Heart palpitations
Nausea

Crucially, these symptoms are typically associated with consuming very high doses (3 grams or more) of MSG on an empty stomach, which is far above the amount found in a typical serving of food.

The Difference Between Added and Natural Glutamate

MSG is simply the sodium salt of glutamic acid, an amino acid found naturally in many foods. When you consume MSG, your body metabolizes the glutamate exactly the same way it metabolizes glutamate from cheese, tomatoes, or seaweed. There is no chemical difference in how your body processes them.

Foods with Naturally Occurring Glutamate

Tomatoes
Parmesan cheese
Mushrooms
Seaweed
Soy sauce
Cured meats

Foods with Added MSG (Often Processed)

Soups (canned and instant)
Packaged seasoning mixes
Frozen meals
Snack foods like chips
Processed meats (hot dogs, deli meats)
Fast food items
Salad dressings and condiments

The Real Culprit: Processed Foods, Not Just the Additive

A significant part of the MSG misconception is the tendency to blame the additive for negative reactions that are actually caused by other factors. MSG is frequently added to highly processed foods that are high in sodium, fat, and calories. Experts suggest that side effects like headaches or flushing are more likely a response to the overall unhealthy profile of these foods, rather than the MSG itself. In fact, using MSG can sometimes allow manufacturers to reduce the total sodium content while maintaining flavor, as it contains about one-third the amount of sodium as table salt.

A Comparison of MSG Concerns vs. Scientific Findings


Concern	Anecdotal Claim	Scientific Finding
Allergy Risk	MSG causes severe allergic reactions, sometimes called Chinese Restaurant Syndrome.	No credible evidence links MSG to true allergic reactions (immune-based) in most people. Reactions are rare intolerances (MSC) triggered by high doses.
Toxicity	MSG is a neurotoxin that causes brain damage and cell death.	Concerns arise from older animal studies using injections or extremely high, unrealistic doses. Normal oral intake does not pass the blood-brain barrier in significant amounts.
Obesity Link	MSG makes food tastier, leading to overeating and obesity.	Studies are contradictory. While palatability can increase intake, some research suggests umami can promote feelings of fullness. The issue is more about the processed foods MSG is found in.
Metabolic Issues	MSG causes insulin resistance and diabetes.	Older animal studies used injections, not dietary intake. Current human evidence on moderate dietary MSG intake does not support this link.

Conclusion: Making Informed Dietary Choices

For the average person, MSG is a safe and well-researched flavor enhancer. The core issue with what is unsafe about MSG lies not in the additive itself, but in the context of its use within a diet heavily reliant on processed foods. Instead of solely blaming MSG, a more balanced approach involves understanding that the high sodium, unhealthy fats, and refined carbohydrates often found alongside it are more significant health concerns. For those who suspect they are sensitive, the best approach is to read food labels and monitor personal intake, focusing on a diet rich in whole, unprocessed foods. This perspective moves beyond the historical, unsubstantiated fear and towards informed, evidence-based nutrition choices.

This article is for informational purposes only and is not medical advice. Consult a healthcare professional for personalized dietary guidance.

Frequently Asked Questions

For most people, MSG does not cause headaches. However, a very small subset of the population (less than 1%) who are sensitive to MSG may experience mild and temporary headaches if they consume a very large amount (over 3 grams) without food.

Claims of MSG acting as a neurotoxin are based on older, flawed animal studies that used extremely high, unrealistic doses, often by injection. Scientific evidence confirms that dietary MSG does not cross the blood-brain barrier in significant amounts, and it is not a neurotoxin for humans when consumed normally.

No, MSG is not considered a food allergen, as it does not typically trigger an immune-system-based response. Any reactions, categorized as MSG Symptom Complex, are a form of food intolerance.

The term 'Chinese Restaurant Syndrome' is dated and has been criticized for being misleading and rooted in xenophobia. Modern research has not found a clear link between MSG and the reported symptoms. The current medical term for sensitivity reactions is MSG Symptom Complex.

For most people, there is no amount of MSG that is considered 'too much' from a safety perspective, within typical dietary amounts. Adverse reactions in sensitive individuals are usually linked to consuming 3 grams or more at once on an empty stomach, which is a rare and exceptionally high dose.

Yes, you can. MSG contains about one-third of the sodium of table salt. By substituting some table salt with MSG, you can reduce the total sodium in a dish while still enhancing flavor.

Often, food containing added MSG is also highly processed and high in sodium and unhealthy fats. It's likely that these other factors, rather than the MSG itself, are the cause of symptoms like flushing or headaches in most people.