E-numbers / Acidity regulators / E504
also: Magnesite · Magnesia alba
A mineral salt derived from magnesium, used to regulate acidity, prevent caking, and add firmness in a range of foods.
Scan a barcode to check a food for magnesium carbonate. NutraSafe Pro · £3.99/month · iOS
Wheat Flour, Wheat Starch, Emulsifier: Soya Lecithins, Sweetener: Saccharin, Raising Agents: Sodium Hydrogen Carbonate, Magnesium Carbonate, Salt
Magnesium carbonate is an inorganic mineral salt that occurs naturally as the mineral magite.
85
of the 43,325 UK supermarket foods we checked declare E504 in their ingredients
That is 0.2%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Magnesium carbonate is an inorganic mineral salt that occurs naturally as the mineral magite. The food-grade form is produced synthetically by reacting magnesium salts with sodium carbonate or carbon dioxide. It exists as a white, odourless powder and is the same mineral element found in drinking water and many vegetables.
As an acidity regulator it neutralises excess acid, buffering pH in food and drink. As an anticaking agent it absorbs moisture and keeps powdered foods free-flowing. At higher concentrations it can also act as a firming agent and a colour-retention aid by maintaining the alkaline environment that preserves chlorophyll in green vegetables.
Most commonly found in table-top sweetener tablets and powders (where it prevents clumping), cocoa powder and drinking chocolate mixes, flour (as a processing aid), some salt and seasoning blends, and certain confectionery. On a UK ingredient label it appears as 'magnesium carbonate', 'E504', or 'E 504'.
Magnesium is an essential dietary mineral, required for hundreds of enzyme reactions, muscle function, and bone structure. The carbonate form contributes to dietary magnesium intake but is not a meaningful supplement vehicle at the small quantities used in food. Regulatory bodies treat inorganic magnesium salts as nutritional minerals rather than xenobiotics, which is why no numerical acceptable daily intake has been established.
EFSA concluded that no numerical ADI was necessary for magnesium carbonates because magnesium is an essential nutrient and dietary exposure from food additive use does not raise concern.
At very high supplemental doses, magnesium salts draw water into the gut and act as an osmotic laxative. This is the basis of some over-the-counter antacid products. The amounts present in food as E504 are far below those used therapeutically, so this effect is not a practical consideration for the typical consumer eating foods containing it.
Magnesium carbonate is used therapeutically as an antacid and mild laxative at gram-level doses, well above any quantity consumed as a food additive.
People with kidney disease who are medically advised to limit magnesium intake should note that fortified or heavily supplemented products may carry meaningful amounts. Look for 'magnesium carbonate' or 'E504' on the label and check with a GP if magnesium restriction applies.
Magnesium carbonate is one of the most straightforwardly ordinary food additives: a mineral salt built from an element the body already needs and manages. It has been used in food for generations, was fully reviewed by EFSA in 2018 with no flags raised, and no credible independent research has identified a concern. The science here is settled and the picture is consistent.
No. Magnesium carbonate (E504) is approved for use in the UK under the assimilated EU Regulation 1333/2008, retained in UK law from 31 December 2020. It is authorised in England, Scotland, and Wales.
In most categories it is permitted at 'quantum satis', meaning manufacturers use the lowest quantity needed to achieve the intended effect, with no fixed upper limit set in law. A few specific categories may have defined limits in the full regulatory annex.
Table-top sweetener tablets and powders are among the most common sources. It also appears in cocoa and drinking chocolate mixes, seasoning and salt blends, some flour products, and certain confectionery where it prevents caking or controls acidity.
Yes. Magnesium carbonate is a mineral salt with no animal-derived ingredients. It is suitable for vegans and vegetarians.
Last reviewed: 20 June 2026
It's the only app that does thisUKJaneK
You Need This AppGmac2005
Best AppGK getting skinny UK App Store reviews
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
NutraSafe Pro · £3.99/month · iOS
