E food additives

E621 – Monosodium glutamate (MSG)

Orange grain dots symbol for food additive with some concerns (E number classification – ORANGE level).

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Safety grading ORANGE – SOME CONCERNS

Why ORANGE? Monosodium glutamate (MSG, E621) is one of the world’s most widely used flavour enhancers. It delivers the savoury “umami” taste, the same taste quality naturally present in tomatoes, mushrooms, seaweed and aged cheeses. Regulatory bodies generally consider MSG safe at permitted levels: in the EU, the European Food Safety Authority (EFSA) derived a group Acceptable Daily Intake (ADI) of 30 mg/kg body weight/day (expressed as glutamic acid) for glutamic acid and glutamates (E620–E625) following its 2017 re‑evaluation. In contrast, the WHO/FAO Joint Expert Committee on Food Additives (JECFA) historically assigned glutamates a group “ADI not specified” – a designation used when there are no safety concerns at use levels consistent with good manufacturing practice. The US FDA classifies MSG as GRAS (Generally Recognized As Safe) and continues to authorise its use in foods.

So why not a full GREEN grade? Two factors keep MSG in the ORANGE category for this project: (1) exceedance potential – EFSA estimated that some population groups with high consumption of glutamate‑rich processed foods could exceed the 30 mg/kg bw/day ADI, prompting recommendations to lower maximum permitted levels in certain categories; and (2) consumer reports of sensitivity (headache, flushing, tingling, etc.), often called “MSG symptom complex.” Controlled trials have not consistently reproduced these reactions at typical dietary doses, but a small subset of individuals may experience symptoms at higher single bolus intakes taken without food. In short, the weight of evidence supports safety at normal exposures, yet ADI management, occasional sensitivity, and historical controversy justify an ORANGE – SOME CONCERNS grade rather than GREEN.

Important note on sodium: MSG contains sodium but only about one‑third as much sodium as table salt by weight. It can therefore help reduce total sodium in recipes when used to boost flavour while lowering added salt, however, this benefit depends on overall formulation and diet patterns.

Should You Avoid MSG?

Most people do not need to avoid MSG when it is consumed as part of a balanced diet and within regulatory limits. If you notice you are sensitive (e.g., headaches or flushing after high‑MSG meals), consider moderating intake and avoiding large single doses on an empty stomach. Individuals advised to restrict dietary sodium should remember that MSG still contributes some sodium. Parents may wish to limit heavily processed snacks that combine MSG with high fat/salt. Choosing whole foods and cooking at home naturally keeps glutamate intake moderate while retaining the option to use small amounts for umami.

Common Uses

  • Snack foods (crisps/chips, savoury mixes) to boost umami and overall flavour.
  • Instant noodles, packet soups and meal bases for depth and meatiness.
  • Processed meats and ready meals to enhance savoury notes.
  • Sauces, condiments and bouillon/stock cubes.
  • Restaurant cooking and seasonings (often under brand names like “Aji‑No‑Moto”).

Common names / Synonyms

  • Monosodium glutamate, Sodium glutamate, MSG
  • E621, INS 621
  • L‑glutamic acid, monosodium salt (monohydrate)
  • Trade/culinary names: Aji‑No‑Moto®, Accent®, Vetsin/Ve‑Tsin

What is Monosodium glutamate?

Chemistry & taste: MSG is the sodium salt of the amino acid L‑glutamic acid. In water and in foods, it dissociates to sodium ions and free glutamate, which stimulates specific umami taste receptors (e.g., T1R1/T1R3 and mGluR variants) on the tongue. Free glutamate also occurs naturally in many foods (tomato, parmesan, soy sauce, kombu). Because umami enhances savoury perception, MSG can improve palatability and allow formulators to reduce added salt while maintaining consumer acceptance.

How it’s produced: Modern production uses microbial fermentation of carbohydrate substrates (e.g., sugar beet, cane sugar, tapioca or molasses) by selected Corynebacterium or Brevibacterium strains that excrete glutamic acid into the broth. After fermentation, glutamic acid is recovered and neutralised with sodium to form crystalline MSG, then filtered, decolorised and crystallised to food‑grade purity. This fermentation route has largely replaced historical extraction from seaweed or hydrolysed proteins due to efficiency and consistency.

Behaviour in foods & digestion: MSG is highly soluble and heat‑stable under normal cooking conditions, making it suitable for soups, sauces and seasonings. In the gastrointestinal tract, glutamate is predominantly metabolised by intestinal cells as an energy source; only small amounts reach systemic circulation. The body does not distinguish between glutamate from MSG and glutamate from foods—both are chemically identical and handled through the same metabolic pathways.

Safety overview: Across decades of study, typical dietary exposure has not been shown to cause adverse effects in the general population. EFSA’s 2017 review set a conservative group ADI of 30 mg/kg bw/day (as glutamic acid) for additives E620–E625 and suggested lowering some maximum permitted levels to minimise potential exceedance in high consumers. JECFA has retained a group ADI “not specified” for glutamates when used according to good manufacturing practice, and the US FDA continues to recognise MSG as GRAS. Anecdotal sensitivity exists but is uncommon and inconsistent in blinded trials. Overall, MSG remains authorised globally as a flavour enhancer within established conditions of use.

Where it’s allowed (EU vs US)

EU: Authorised as E621 (flavour enhancer). EFSA’s 2017 opinion set a group ADI of 30 mg/kg bw/day (as glutamic acid) for glutamates and recommended lowering certain maximum levels, labelling must declare “monosodium glutamate” or “E621.”

US: FDA regards MSG as Generally Recognized as Safe (GRAS) for intended uses, it must appear on ingredient lists when added. Both jurisdictions permit use within good manufacturing practice and category limits.

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