E-numbers / Other additives / E648
A magnesium salt of gluconic acid used as a mineral source in food supplements. Not a permitted food additive in the UK or EU.
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Carbonated Water, Malted Barley, Electrolytes (Magnesium Gluconate, Potassium Lactate and Sea Salt), Flavouring, Acerola Juice Powder, Hop Extract
This is not on the UK list of approved food additives, so you will not normally see this E number on a UK label.
1
of the 43,325 UK supermarket foods we checked declare E648 in their ingredients
That is under 0.1%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. This is not on the UK list of approved food additives, so you will not normally see this E number on a UK label.
Magnesium gluconate is the magnesium salt of gluconic acid, a naturally occurring organic acid found in fruit, honey, and wine. It is a white, water-soluble powder. As a compound it is used primarily in pharmaceutical and dietary supplement products to deliver magnesium.
In supplement contexts it delivers bioavailable magnesium, a mineral involved in hundreds of enzymatic reactions including energy metabolism, muscle and nerve function, and protein synthesis. In the limited food-additive role the E648 designation would imply, it would function as an acidity regulator or mineral fortifier.
E648 is not currently authorised as a food additive in UK or EU food products. Magnesium gluconate does appear as a permitted mineral source in food supplements under Directive 2002/46/EC (food supplements law), where it is listed by its chemical name rather than an E number. On a supplement label it reads as 'magnesium gluconate' in the ingredients.
Magnesium gluconate is used in supplements because gluconate salts of minerals tend to be relatively soluble and well-absorbed in the gut compared to insoluble forms such as magnesium oxide. The evidence base here is for magnesium itself, not for the gluconate carrier, which is metabolised to CO2 and water.
Magnesium gluconate is listed as a permitted mineral source form in food supplements under EU Directive 2002/46/EC, indicating regulatory acceptance of its use for mineral delivery.
E648 does not appear in Annex II of EU Regulation 1333/2008 or the UK FSA approved-additives list. No EFSA scientific opinion or SCF opinion on E648 as a food additive appears to exist. Its absence from the approved list means it has not been formally evaluated and authorised for use as a food additive.
E648 does not appear in Annex II of the UK assimilated version of EU Regulation 1333/2008 or the UK FSA approved-additives list. The E640 range in Annex II contains only E640 (Glycine), E641 (L-leucine) and E650 (Zinc acetate).
No specific avoidance group, as E648 is not an authorised food additive and you would not encounter it as an E number in food ingredient lists. In supplement form, people with kidney disease should seek medical advice before taking supplemental magnesium in any form, as impaired kidneys cannot excrete excess magnesium efficiently.
E648 occupies an unusual position: it carries an E number assignment in some databases and catalogues, but it is not authorised for use as a food additive under UK or EU law. You will not find it on food packaging as 'E648'. Magnesium gluconate itself is a real compound with legitimate use as a mineral supplement ingredient, but in that context it is labelled by name, not by E number. The absence of an authorised food-additive use means there is no EFSA safety opinion on it in that role, and no maximum permitted levels have been set.
E648 is not listed as a permitted food additive in the UK or EU, which means it is not authorised for use as a food additive in food products sold here. It is not that it was banned and removed: it was never approved under the food additives framework. Magnesium gluconate is separately permitted as a mineral source in food supplements, under different legislation.
Some private databases and catalogues assign E numbers to compounds that have been proposed or used in other regulatory contexts, even if they are not approved EU or UK food additives. The official reference is the UK FSA approved-additives list and Annex II of the retained EU Regulation 1333/2008, where E648 does not appear.
No food products in the UK or EU are authorised to include E648 as a food additive. Magnesium gluconate may appear in food supplements listed by its chemical name, not as an E number.
Magnesium gluconate is produced synthetically from gluconic acid and magnesium salts and contains no animal-derived ingredients, so it is considered vegan. However, since E648 is not an authorised food additive, the practical relevance of this question is limited to supplement products.
Last reviewed: 20 June 2026
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