Monoammonium glutamate
The ammonium salt form of glutamate, added to processed foods to intensify savoury flavour. One of six glutamate additives used as flavour enhancers.
At typical processed-food consumption levels, exposure to added glutamates can exceed the dose linked to headaches and blood-pressure rises in human studies, particularly in children and toddlers.
What is it?
Monoammonium glutamate is the ammonium salt of glutamic acid, an amino acid that occurs naturally in proteins and fermented foods. As an additive it is produced by fermentation or chemical synthesis. It belongs to the glutamate family (E620 to E625), all of which contribute free glutamate to the body. The ammonium component is nutritionally trivial at food-use levels.
What does it do?
Free glutamate activates taste receptors on the tongue that respond to umami, the fifth basic taste associated with savoury, meat-like depth. At low concentrations it can suppress bitterness and amplify other flavours, allowing manufacturers to reduce more expensive ingredients such as meat extracts, cheese or stock. In food technology it is functionally interchangeable with monosodium glutamate (MSG, E621).
Where you will see it
Found in instant noodles, dried soups, stock cubes, seasoning blends, processed meats, savoury snacks, ready meals, sauces and condiments, and some fine bakery wares. On a UK ingredient label it appears as monoammonium glutamate or E624.
What the science says
Exposure from diet regularly exceeds the ADI in children
EFSA set a group ADI of 30mg per kilogram of bodyweight per day for all glutamate additives combined. However, exposure estimates for infants, toddlers and children at high consumption levels exceeded not only the ADI but also doses linked to adverse effects in human studies. Adults can also breach the ADI through heavy processed-food use.
EFSA derived a group ADI of 30mg/kg bodyweight per day for glutamic acid and glutamates (E620-E625) expressed as glutamic acid, and found that dietary exposure exceeded this ADI across all age groups at mean and high consumption levels.
Modelled exposure exceeded doses associated with MSG symptom complex (above roughly 43mg/kg/day), headaches (above roughly 86mg/kg/day), and blood-pressure rises (above roughly 150mg/kg/day) in some high-consuming children.
MSG symptom complex: real in some people, disputed as a population risk
A subset of people report headaches, flushing, chest tightness and sweating after consuming large amounts of glutamate, a pattern historically called 'Chinese restaurant syndrome'. Controlled blinded studies have produced mixed results: symptoms are difficult to reproduce consistently in double-blind conditions, but high-dose challenges in sensitive individuals do show effects in some trials. The mechanism is not fully established.
Double-blind crossover trials in self-reported MSG-sensitive individuals have produced inconsistent results, with some studies finding no significant symptom difference versus placebo at moderate doses and others finding effects at high doses.
EFSA concluded that available data were insufficient to establish a dose-response relationship for the MSG symptom complex and recommended further research.
Animal and developmental toxicity: no adverse histopathological findings at high doses
In animal studies, glutamates showed low acute toxicity. Increased kidney and spleen weights were observed at very high doses but were not accompanied by tissue damage and were not classified as adverse by the EFSA panel. No genotoxicity was found. Neurodevelopmental effects observed in some older animal studies were not reproduced under more rigorous conditions.
The NOAEL used to set the ADI came from a neurodevelopmental toxicity study in rats; no adverse histopathological findings accompanied organ-weight changes seen at higher doses, and genotoxicity testing raised no concerns.
Regulatory recommendation to lower maximum permitted levels
Because modelled exposure exceeded the ADI across multiple age groups, EFSA recommended in 2017 that the European Commission revise the maximum permitted levels for glutamate additives in the principal food categories. As of the most recent regulatory review, those revisions had not been fully implemented.
The EFSA panel recommended that the European Commission reconsider the maximum permitted levels for glutamate food additives (E620-E625) in Annex II of Regulation 1333/2008 to bring estimated exposure within the ADI.
Where it stands with the regulators
Who should be careful
People who have experienced headaches, flushing or chest tightness after glutamate-rich meals may want to limit added glutamates. Children eating large amounts of processed soups, snacks and seasonings are most likely to exceed the combined ADI for the glutamate group. Look for monoammonium glutamate or E624 on ingredient labels, alongside E620, E621, E622, E623 and E625 which all contribute to the same group total.
The honest read
E624 contributes exactly the same free glutamate as MSG (E621), just via an ammonium salt rather than sodium. The science on population-level exposure is genuinely concerning: EFSA's own modelling in 2017 found that dietary exposure to added glutamates exceeds the ADI across all age groups at typical consumption levels, and breaches doses linked to headaches and blood-pressure rises in heavy-consuming children. Whether those modelled exposures translate to measurable health harm in the real population is still debated. The MSG symptom complex exists but is difficult to reproduce consistently in blinded trials. What is not in dispute is that EFSA recommended lowering the permitted limits in 2017 and the regulatory framework has not yet been fully updated to reflect that.
Related additives
Common questions
Is E624 banned in the UK?
No. E624 is on the UK FSA's approved-additives list and remains permitted under the UK's assimilated version of EU Regulation 1333/2008. It is approved across multiple food categories at up to 10g/kg (combined with other glutamate additives).
Is E624 the same as MSG?
Functionally yes: both deliver free glutamate, which produces the savoury umami taste effect. E624 is the ammonium salt and E621 is the sodium salt. The body's exposure to glutamate is the same. EFSA treats them as a group (E620-E625) sharing a combined ADI.
What foods contain E624?
Most commonly found in instant noodles, dried soups, stock cubes, seasoning sachets, processed meats, savoury snacks and ready meals. It reads as monoammonium glutamate or E624 on the ingredient list.
Is E624 vegan?
Yes. Monoammonium glutamate is produced by microbial fermentation or chemical synthesis and contains no animal-derived ingredients.
Sources
- EFSA Panel on Food Additives and Nutrient Sources: Re-evaluation of glutamic acid (E620) to magnesium glutamate (E625) as food additives (2017), EFSA Journal
- PMC open-access version of the EFSA 2017 glutamate re-evaluation
- UK FSA Approved Additives and E Numbers
- Geha RS et al. Multicenter, double-blind, placebo-controlled, multiple-challenge evaluation of reported reactions to monosodium glutamate, Journal of Allergy and Clinical Immunology
- Commission Regulation (EU) 231/2012 - Specifications for monoammonium glutamate (E624)
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