E-numbers / Flavour enhancers / E623
also: calcium di-L-glutamate · calcium glutamate
The calcium salt of glutamic acid, added to processed and seasoned foods to intensify savoury, meaty flavour.
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A 2017 EFSA review of the glutamate family set a group acceptable daily intake for the first time, finding that people who eat a lot of processed foods, especially children, can exceed it through additives alone, before counting naturally occurring glutamate in protein-rich foods.
Why it’s worth knowing. A 2017 EFSA review of the glutamate family set a group acceptable daily intake for the first time, finding that people who eat a lot of processed foods, especially children, can exceed it through additives alone, before counting naturally occurring glutamate in protein-rich foods.
Calcium diglutamate is the calcium salt of glutamic acid, an amino acid that occurs naturally in protein-rich foods such as meat, fish, cheese and tomatoes. Two glutamate molecules bind to one calcium ion to form the salt. It belongs to the E620-E625 glutamate group of flavour enhancers, which includes monosodium glutamate (E621) and the potassium, ammonium and magnesium variants. The calcium version is used partly because it provides a lower-sodium alternative to MSG.
Glutamate activates umami taste receptors on the tongue (the T1R1/T1R3 receptor complex and metabotropic glutamate receptors), producing the savoury, mouth-filling quality described as umami, the fifth basic taste alongside sweet, sour, salty and bitter. It amplifies the perceived intensity of meat, cheese and broth flavours, meaning manufacturers can use less of other ingredients to achieve the same taste impact. It does not add a distinctive flavour of its own but broadens and deepens existing ones.
Seasonings, stock cubes and bouillon, instant noodles and cup soups, packet soups, processed meat products, savoury snacks, sauces, canned and ready meals, and flavoured crisps. On a UK ingredient label it appears as calcium diglutamate or E623.
In 2017 EFSA conducted a full re-evaluation of all six permitted glutamate additives (E620-E625) as a group. For the first time it set a combined group acceptable daily intake of 30 milligrams of glutamic acid equivalent per kilogram of body weight per day, replacing the previous 'not specified' assumption that implied no concern at typical dietary levels. EFSA concluded that the glutamate additives are broken down and handled in the body the same way as naturally occurring glutamate, but that exposure from added glutamates alone could approach or exceed this level in high consumers, particularly children with a diet heavy in processed foods.
EFSA set a group ADI of 30 mg glutamic acid equivalent per kg body weight per day for E620-E625, finding that children who are high consumers of processed foods may exceed this from additive sources alone, not counting natural dietary glutamate.
Prior to 2017, the ADI for glutamates was listed as 'not specified', implying no safety concern at levels needed to achieve a flavour effect. The 2017 re-evaluation changed this position based on updated animal toxicology data.
From the 1960s onwards, some people reported headaches, flushing and chest tightness after eating MSG-containing meals, a cluster labelled 'Chinese Restaurant Syndrome'. Subsequent double-blind, placebo-controlled trials found that the symptoms could not be reliably reproduced when glutamate was given without people knowing whether they had received it or a placebo. The scientific consensus now is that a specific dose-dependent glutamate sensitivity has not been demonstrated in controlled conditions, though a small number of self-identified sensitive individuals continue to report reactions.
Double-blind crossover trials found that reported MSG sensitivity was not consistently reproduced when participants were unaware of which substance they had consumed, and symptoms did not correlate with dose.
A Cochrane-style review concluded that available evidence does not support the existence of a definable MSG sensitivity syndrome, while acknowledging the body of trials is small and some methodological limitations remain.
Studies in rodents given very large doses of glutamate, far above any realistic food exposure, showed lesions in the hypothalamus and effects on appetite-regulating hormones. Regulators and most researchers consider these findings an artefact of dosing at levels that overwhelm the body's normal glutamate handling mechanisms, not evidence of harm at dietary levels. EFSA examined this literature in its 2017 review and determined that the animal data did not indicate a concern at the ADI it established.
Rodent studies involving oral doses of glutamate at several grams per kilogram body weight produced hypothalamic lesions; EFSA concluded these effects were not relevant to human dietary exposure at the group ADI of 30 mg/kg bw/day.
People trying to reduce total glutamate load from processed foods, particularly parents of children who eat a lot of seasoned, pre-packaged or instant foods, should be aware that additive glutamates from multiple products in a day can add up. There is no mandatory allergy label for glutamates. Look for calcium diglutamate or E623 in the ingredients list.
The headline science here is the 2017 EFSA group review: it replaced a decades-old assumption that glutamate additives needed no numerical limit with a specific acceptable daily intake, having looked at animal toxicology data more carefully. That is a genuine change in regulatory position, not a minor tweak. What it means in practice is contested. EFSA itself noted that people eating large amounts of processed food, especially children, could in principle exceed the additive-derived portion of that limit before counting the substantial amounts of glutamate that occur naturally in protein-rich foods. Whether real-world exposure is actually a problem is unresolved: no agency has moved to restrict uses, and natural dietary glutamate dwarfs additive sources for most adults. The 'Chinese Restaurant Syndrome' story, meanwhile, has largely collapsed under controlled testing. The current honest position is: there is more regulatory attention on this group than there was ten years ago, and the exposure question for high consumers of processed food has not been fully closed.
No. E623 is authorised for use in food in England, Scotland and Wales under the UK FSA's approved additives register, which reflects assimilated EU Regulation 1333/2008. It is also permitted across the EU.
It is closely related. Both deliver glutamate, the amino acid that drives umami flavour. E621 is monosodium glutamate (MSG), and E623 is calcium diglutamate, a variant where the glutamate is bound to calcium rather than sodium. The flavour effect is the same. E623 is sometimes used as a lower-sodium alternative to MSG.
Seasonings, stock cubes, packet and cup soups, instant noodles, processed meats, savoury snacks, crisps, ready meals and sauces are the most common sources. Check the ingredients list for calcium diglutamate or E623.
The additive itself is produced synthetically or by fermentation and does not contain animal-derived ingredients. However, the foods it is added to are often meat-based or may contain other animal products. Check the full product ingredients.
Last reviewed: 20 June 2026
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