E621 — Monosodium glutamate
Also labelled: MSG · Mononatriumglutamat · Geschmacksverstärker
Most of what people believe about MSG comes from a 1968 anecdote that blinded trials never reproduced. The reason Frela still rates it moderate has nothing to do with that folklore — it is that EFSA set an intake limit in 2017 and found some people exceed it.
At a glance
- E number
- E621
- Class
- Flavour enhancer
- Origin
- Bacterial fermentation of starch or molasses
- EU status
- Authorised, with maximum levels
- Acceptable daily intake
- 30 mg per kg of body weight per day, as a group with other glutamates (EFSA, 2017)
- Typically found in
- Stock cubes, crisps, instant noodles, seasoning mixes, ready meals, sauces
What it actually is
Monosodium glutamate is the sodium salt of glutamic acid, an amino acid your body makes and uses constantly. Free glutamate is what gives parmesan, ripe tomatoes, soy sauce, mushrooms and cured ham their savoury depth — the taste named umami.
Industrially it is produced by fermenting starch or molasses with bacteria, in much the same way as vinegar or yoghurt cultures. Chemically, the glutamate in a stock cube and the glutamate in a tomato are the same molecule; the body does not distinguish them.
The 'Chinese restaurant syndrome' story
In 1968 a letter to the New England Journal of Medicine described numbness and palpitations after eating at Chinese restaurants, speculating about MSG among other causes. The idea spread rapidly and durably.
It has held up poorly. Double-blind, placebo-controlled trials have largely failed to reproduce the symptoms when participants do not know whether they received MSG, and reviews have consistently found no consistent effect at doses typical of food. Where reactions do occur, they tend to appear only at large doses taken without food.
This history matters because it cuts the other way from what people expect: the famous reason to avoid MSG is the weakest part of the case against it.
What EFSA actually found in 2017
EFSA re-evaluated glutamic acid and glutamates and, for the first time, established a group acceptable daily intake of 30 mg per kg of body weight per day. Previously no numerical limit had been set.
EFSA also estimated dietary exposure and concluded that this ADI can be exceeded in some population groups, particularly at the high end of consumption among children and adolescents. The effects underpinning the limit — headache, blood pressure changes at high doses — were observed well above ordinary intake, but the finding that some people exceed the limit is what changed the picture.
There is also a plain sodium consideration. MSG contributes sodium, though roughly a third as much as an equivalent weight of table salt, and it is often used in products that are already salty.
How Frela scores it
Frela rates E621 moderate risk. That places it below additives with carcinogenicity classifications or mandatory warnings, and above those with no established concern.
In practice MSG rarely determines a product's score on its own. It appears overwhelmingly in stock cubes, crisps, instant noodles and ready meals — foods that NOVA classifies as ultra-processed and that usually carry high salt. The processing and nutrition components generally move the score further than the additive rating does.
Common questions
Is MSG natural or artificial?
The glutamate is identical to the free glutamate in tomatoes and parmesan. The manufacturing route is bacterial fermentation. Whether you call that natural is a labelling question rather than a chemical one.
Why rate it moderate if the syndrome was debunked?
Because the rating does not rest on the syndrome. It rests on EFSA's 2017 group ADI and its finding that some population groups exceed it. Those are different arguments, and only the second one survives scrutiny.
Does avoiding E621 mean avoiding glutamate?
No. Products labelled 'no added MSG' frequently use yeast extract, hydrolysed vegetable protein or fermented ingredients, all of which deliver free glutamate. The label changes; the molecule often does not.
Sources
- EFSA — Re-evaluation of glutamic acid (E620) and glutamates (E621–E625) (2017)
- Regulation (EC) No 1333/2008 on food additives
Last reviewed:
