Is MSG bad for you? The science behind a 50-year myth

Flip over a bag of Doritos, a cup of instant noodles, or a takeout menu, and there it is: "E621" or "monosodium glutamate." For many people, those words trigger an instant association — MSG, that dodgy stuff in Chinese food. The reputation has become so entrenched that restaurants advertise "no MSG added" as a selling point. But does the science actually support the fear, or is something else going on?

In this article we unpack what MSG is, where the "Chinese Restaurant Syndrome" myth came from, what controlled trials actually found, what EFSA's current position is, and what the real issue is — because it is probably not what you think.

What is MSG?

MSG stands for monosodium glutamate — the sodium salt of glutamic acid. Glutamic acid (glutamate) is one of the 20 standard amino acids and is responsible for umami, the fifth basic taste: that deep, savoury, moreish quality you get from a slow-cooked broth or a slice of aged parmesan.

Here is the critical point most people miss: glutamate is a naturally occurring compound found in many everyday foods. Your own body produces it continuously. Natural glutamate sources include:

• Ripe tomatoes and tomato paste
• Aged cheeses (parmesan, aged cheddar)
• Mushrooms, soy sauce, seaweed (kombu)
• Breast milk — one of the first umami experiences a newborn encounters

The "natural glutamate" in a tomato and the "additive glutamate" in E621 are chemically identical molecules. Your body cannot tell them apart. That single fact already reveals why the "MSG is an artificial poison" narrative is incomplete.

Where did "Chinese Restaurant Syndrome" come from?

MSG's bad reputation did not grow from rigorous science — it grew from a single letter published in a medical journal in 1968. A physician wrote to the New England Journal of Medicine describing how, after eating at Chinese restaurants, he experienced neck numbness, palpitations, and weakness, and speculated that MSG might be responsible. The press ran with it, coined "Chinese Restaurant Syndrome," and a cultural fear was born.

The problem: this was never a controlled study. It was one person's personal observation. And when scientists spent the following decades actually testing the hypothesis, the results did not support it.

What did controlled trials find?

This is where the myth unravels. Double-blind, placebo-controlled trials — where neither the participants nor the researchers know who received MSG and who received a placebo, the most reliable experimental design available — found no consistent causal link between MSG and the reported symptoms.

• People who believed they were sensitive to MSG reported symptoms when they thought they had consumed it, even when they had not — a textbook nocebo effect.
• When MSG was consumed alongside food in normal portions, symptoms could not be attributed specifically to MSG.
• Very large doses (pure MSG on an empty stomach) triggered mild, transient symptoms in some sensitive individuals, but this bears no resemblance to eating Chinese takeout or a packet of instant noodles.

This is why, in NeBu's additive database, we deliberately use measured language on this point: "transient symptoms reported in some individuals; causality contested." Accurate information sits somewhere between inflating a fear and declaring something completely harmless — and it takes the evidence seriously either way.

EFSA's current position

The European Food Safety Authority (EFSA) re-evaluated glutamates in 2017 and, for the first time, established a group Acceptable Daily Intake (ADI):

• 30 mg/kg body weight/day (expressed as glutamic acid, covering the group of glutamate additives).
• EFSA noted that this threshold can be exceeded in some high-consumer groups — particularly children eating diets heavy in additives — and recommended that certain maximum permitted levels be reviewed.

EFSA's message is calibrated, not alarmist: MSG is not a dangerous poison, but it is not unlimited either. In diets dominated by ultra-processed products, cumulative glutamate intake from multiple sources can add up.

The real issue: context, not MSG itself

Here is the most important transparency point in this whole article: MSG itself is probably far more benign than its reputation suggests, but the products that contain it do tell you something meaningful.

Where do you encounter MSG most often? Crisps, instant noodles, flavour sachets, chicken-flavoured bouillon cubes, fast food seasoning, packaged savoury snacks — in other words, ultra-processed foods. The genuine health concern with these products is not the MSG; it is the high sodium content, low nutrient density, and the ultra-processed nature of the product overall.

Put another way: MSG is frequently a signal that a product is ultra-processed — but it is not the culprit on its own. Being afraid of MSG while ignoring total salt and processing level means aiming at the wrong target.

One more nuance worth noting: MSG contains roughly a third of the sodium found in table salt by weight. Some manufacturers deliberately use MSG to reduce overall sodium while preserving flavour. In the right context, MSG can actually represent a lower-sodium trade-off compared with simply adding more salt.

How NeBu scores MSG

When NeBu evaluates E621, we work to avoid two opposite traps:

• The myth trap: we do not stamp MSG as dangerous. Amplifying a scientifically unsupported fear is not honest information — it is the same mistake apps like Yuka make when they flag MSG as a high-risk ingredient without distinguishing between the additive itself and the context it appears in.
• Context blindness: at the same time, we do not pretend MSG's presence is irrelevant. Because it appears predominantly in ultra-processed products, we factor in total salt load, nutrient density, and processing level across the whole product profile.

So when you see E621 on a product card in NeBu, instead of "run away from this product," you get a clear, evidence-based picture of the product's actual nutritional profile. Clarity over fear.

Summary

• MSG (E621) is the sodium salt of glutamate, the amino acid responsible for umami; glutamate is found naturally in tomatoes, aged cheese, and breast milk — it is chemically identical to the additive form.
• "Chinese Restaurant Syndrome" originated in a single 1968 letter to a journal, not a controlled study; double-blind trials found no consistent causal link between MSG and the reported symptoms (largely a nocebo effect).
• EFSA established a group ADI of 30 mg/kg body weight/day in 2017; high-consumer groups can exceed this, so "no limit" does not apply.
• The real concern is not MSG but the fact that products containing it tend to be ultra-processed and high in sodium.
• NeBu avoids both the myth trap and context blindness, evaluating the whole product rather than singling out one additive.

Sources

• EFSA — Re-evaluation of glutamic acid and glutamates (group ADI 30 mg/kg bw/day, 2017): https://www.efsa.europa.eu/en/efsajournal/pub/4910
• FDA — Questions and Answers on Monosodium Glutamate (MSG): https://www.fda.gov/food/food-additives-petitions/questions-and-answers-monosodium-glutamate-msg
• WHO/JECFA — Glutamic acid and salts evaluation: https://apps.who.int/food-additives-contaminants-jecfa-database/

For the full detail of the NeBu methodology, take a look at our /methodology page.