Is MSG (E621) bad for you? What the science says about monosodium glutamate
MSG has one of the worst reputations of any food ingredient — most of it built on a single 1968 letter, not evidence. Here's what EFSA and controlled studies actually found about E621.
Monosodium glutamate — additive E621 — is the sodium salt of glutamic acid, an amino acid found naturally in tomatoes, cheese, mushrooms and human breast milk. It's added to savoury foods to boost umami. Few ingredients carry as much fear as MSG, so it's worth separating the reputation from the regulatory record.
Where the fear came from
The panic traces to a single 1968 letter to a medical journal coining "Chinese restaurant syndrome" — headaches and flushing supposedly caused by MSG. Decades of double-blind, placebo-controlled trials have since failed to reproduce a consistent reaction in the general population at normal dietary levels. The effect largely disappears when people don't know whether they've had MSG.
What the regulators concluded
- EFSA re-evaluated glutamic acid and glutamates in 2017 and, for the first time, set a group Acceptable Daily Intake of 30 mg per kg of body weight per day (expressed as glutamic acid). It noted some people could exceed this at the high end of consumption, which is why it's an ADI worth being aware of rather than an "eat unlimited" verdict.
- The US FDA classifies MSG as "generally recognized as safe" (GRAS), while requiring it to be labelled when added.
The honest summary: at normal dietary amounts MSG is considered safe by regulators, and the classic "MSG reaction" isn't supported by controlled evidence — but like salt, it's a sodium source, so it's still worth seeing where it appears.
Why "no MSG" labels can mislead
Products proudly labelled "no added MSG" often still contain free glutamates from yeast extract, hydrolysed protein or stock — chemically the same compound your tongue tastes. That's a good example of a true-but-selective claim, and exactly why scanning the actual ingredient list beats trusting the front of the pack. Forkin surfaces E621 and its context on any product you scan, alongside the nutrition, processing and environmental scores. Our E-numbers guide covers how the approval system works.