MSG
A flavour enhancer made by fermentation that gives food a savoury, umami taste. The same compound also occurs naturally in foods like tomatoes, cheese and mushrooms.
EFSA found UK-style intakes can exceed its safe daily limit in infants, toddlers and children, and high single doses without food have triggered transient headaches in some people.
What is it?
The sodium salt of glutamic acid, an amino acid. Made commercially by fermenting starch, sugar beet, sugar cane or molasses with bacteria, then crystallised into a white powder. The glutamate it delivers is identical to glutamate found naturally in many foods.
What does it do?
Adds umami, the savoury 'fifth taste'. Free glutamate binds taste receptors on the tongue and intensifies the meaty, brothy depth of a dish, letting manufacturers boost savouriness without adding more meat, salt or stock.
Where you will see it
Crisps, stock cubes, instant noodles, gravy granules, ready meals, savoury snacks, soy and seasoning sauces, and takeaway food. On a UK label it appears as 'flavour enhancer (E621)', 'monosodium glutamate' or 'MSG'.
What the science says
EFSA safe-intake limit and exposure
In 2017 EFSA re-evaluated glutamic acid and glutamates and set a group acceptable daily intake of 30mg per kg of body weight per day, from animal studies. It then found that real-world intakes can exceed this limit, and at high intakes can reach doses linked to effects in humans, for some groups, particularly infants, toddlers and children. This is about how much, not a claim the additive is dangerous at normal use.
Group ADI set at 30mg/kg body weight/day, expressed as glutamic acid, for E620-E625, from a no-effect level of 3,200mg/kg/day in a neurodevelopmental study with a 100-fold safety margin.
Mean intakes exceeded the ADI in infants, toddlers, children and adolescents; at high (95th percentile) intakes all population groups exceeded it.
Doses linked to human effects above the ADI: MSG symptom complex above 42.9mg/kg/day, headache around 85.8mg/kg/day, blood-pressure rise at 150mg/kg/day, raised insulin above 143mg/kg/day.
'Chinese restaurant syndrome' and the symptom claims
The idea that MSG causes headaches, flushing and palpitations began with a 1968 letter and became known as 'Chinese restaurant syndrome'. When tested under double-blind conditions, where neither participant nor researcher knows who got MSG, the reported reactions have not reproduced consistently, especially when MSG is eaten with food rather than as a large dose on an empty stomach. Symptoms in self-identified sensitive people were inconsistent, mild and not reliably triggered.
Double-blind, placebo-controlled studies did not consistently reproduce a symptom pattern at realistic dietary doses; reactions in self-reported sensitive people were inconsistent and not serious.
A US FASEB review found short-term, transient, generally mild symptoms (headache, numbness, flushing, tingling, palpitations, drowsiness) in some sensitive people only after 3g or more of MSG taken without food, a dose far above what a normal meal delivers.
Glutamate is also natural
Glutamate is one of the most common amino acids in the diet and is naturally present, in free form, in many everyday foods. The body handles glutamate from MSG and glutamate from these foods the same way.
Free glutamate occurs naturally in tomatoes, Parmesan and other aged cheeses, mushrooms, peas, walnuts and meats; the body does not chemically distinguish added from naturally occurring glutamate.
Where it stands with the regulators
Who should be careful
Parents watching young children's intake of heavily seasoned processed snacks, and anyone who has noticed a reaction after large MSG-heavy meals, can limit it by checking for 'flavour enhancer (E621)', 'monosodium glutamate' or 'MSG' on the label.
The honest read
MSG carries one of the longest-running food scares. The 'Chinese restaurant syndrome' story came from a single 1968 letter, and when researchers tested it under double-blind conditions at amounts you would actually eat, the symptoms did not reliably appear, with effects in self-reported sensitive people being inconsistent and mild. The separate, evidenced point is intake: EFSA's 2017 review found that UK-style consumption can push past its proposed daily limit for infants and children, which is why it set a numerical limit and asked for lower permitted levels. So the headline scare and the real regulatory nuance are two different things.
Related additives
Common questions
Is E621 (MSG) banned in the UK?
No. E621 is an approved flavour enhancer in Great Britain and the EU under the food additives regulation, and the US FDA classes it as generally recognised as safe. EFSA's 2017 review kept it permitted but set a daily intake limit and recommended lower maximum levels in food.
Does MSG cause headaches?
Double-blind trials have not consistently linked normal dietary MSG to headaches. EFSA noted headache reported in studies at around 85.8mg/kg body weight/day, and a US FASEB review found transient symptoms in some sensitive people only after 3g or more taken without food, well above a typical meal's amount.
What foods contain E621?
Crisps, stock cubes, instant noodles, gravy granules, ready meals, savoury snacks, soy and seasoning sauces, and many takeaways. Glutamate also occurs naturally in tomatoes, aged cheese, mushrooms and meats, where it is not labelled as MSG.
Is E621 vegan?
Yes. Commercial MSG is made by bacterial fermentation of plant sources such as starch, sugar beet, sugar cane or molasses, with no animal-derived ingredients.
Sources
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
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