E-numbers / Other additives / E530
also: Magnesia · burnt magnesia
A naturally occurring mineral compound used in tiny amounts to stop powdered foods from clumping together.
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Magnesium oxide is an inorganic mineral salt produced by heating magnesium carbonate or magnesium hydroxide to high temperatures.
23
of the 43,325 UK supermarket foods we checked declare E530 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
Magnesium oxide is an inorganic mineral salt produced by heating magnesium carbonate or magnesium hydroxide to high temperatures. It appears as a fine white powder and is chemically identical to the mineral periclase. It also exists as a pharmaceutical-grade antacid and laxative. The food-grade form is identical in chemistry to the mineral, just highly purified.
In food, magnesium oxide acts as an anti-caking agent: the fine particles coat larger powder granules, reducing their tendency to absorb moisture and stick together. It also acts as a mild acidity regulator, raising the pH of a mixture slightly. It provides a source of magnesium, an essential mineral nutrient.
Most commonly found in dried milk powders, cocoa powders, table salt, icing sugar, and dried vegetable powders. Also used in some dietary supplements and fortified foods as a magnesium source. On a UK label it appears as 'magnesium oxide' or 'E530'.
Magnesium is an essential mineral involved in hundreds of enzymatic reactions in the body, including muscle and nerve function, blood sugar regulation, and bone development. At the small amounts present in food as an anti-caking agent, the contribution to daily magnesium intake is minimal. When used in supplements or fortified foods, the dose becomes nutritionally relevant.
Magnesium oxide has lower bioavailability than some other magnesium salts (such as magnesium citrate), meaning a smaller proportion of the mineral is absorbed from the gut.
At high doses, such as those found in medicinal magnesium oxide products, the compound draws water into the bowel and can cause loose stools or diarrhoea. This effect is well-documented in pharmaceutical contexts. The amounts used in food as an anti-caking agent are far below the doses that produce this effect, so it is not a practical concern from food use alone.
EFSA noted that magnesium intakes above approximately 250mg per day from supplemental sources can cause diarrhoea in some individuals; this threshold is not relevant to amounts from food additive use.
People with kidney disease should be aware that impaired kidneys struggle to excrete excess magnesium; large amounts from supplements containing E530 could lead to elevated blood magnesium levels. This is not a concern from ordinary food use. Look for 'magnesium oxide' or 'E530' on the label if monitoring magnesium intake for medical reasons.
Magnesium oxide has been used in food and medicine for a very long time. The quantities present as an anti-caking agent in food are small and well within accepted levels. The main science discussion around magnesium oxide concerns its relatively poor absorption compared to other magnesium supplement forms, and the laxative effect at high supplemental doses. Neither of these is a concern in ordinary food use. There is no ongoing regulatory debate, no proposed ban, and no animal or human study pointing to harm at food-additive levels.
No. Magnesium oxide is approved for use in the UK under the UK FSA approved-additives list, which retains the framework of EU Regulation 1333/2008. It is permitted in a range of foods at quantum satis levels.
At the small amounts used as an anti-caking agent in food, no physiological effect has been established. High doses of magnesium oxide from supplements can cause loose stools or diarrhoea, but the quantities in food are far below this threshold.
Dried milk powders, cocoa powder, table salt, icing sugar, and some food supplements are the most common sources. Check the ingredients list for 'magnesium oxide' or 'E530'.
Yes. Magnesium oxide is derived from inorganic mineral sources and contains no animal-derived ingredients. It is suitable for vegans and vegetarians.
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