E530 - Magnesium oxide

At a glance

This mineral additive shows up in foods and supplements for simple, practical reasons.

• What it is: Magnesium oxide, an inorganic mineral oxide (MgO), also known as magnesia
• What it does: Helps manage acidity (pH) and can supply dietary magnesium
• Where it’s used: Fortified foods and drinks, nutrition powders, and many multivitamin/mineral supplements
• How it’s listed: “Magnesium oxide” or “E530”
• Dietary notes: Vegan-friendly, gluten-free, and not made from allergens

Why is Magnesium oxide added to food?

Manufacturers use magnesium oxide to control acidity (as a pH control agent) and to provide magnesium as a nutrient supplement, both under current good manufacturing practice rules set by the U.S. Food and Drug Administration (FDA).¹ In the European Union (EU), it is an approved food additive with the designation E530 and has official purity specifications.²

What foods contain Magnesium oxide?

You are most likely to see magnesium oxide on labels of:

• Multivitamin/mineral tablets and powders
• Fortified foods and drinks (for example, some nutrition shakes or mixes)
• Other processed foods where slight neutralization of acidity is helpful

On ingredient lists, it may appear alongside other acidity regulators or flow agents such as calcium carbonates, silicon dioxide, or calcium silicate.

What can replace Magnesium oxide?

Possible substitutes depend on the job it needs to do:

• For pH control: calcium carbonates, potassium carbonates, or sodium hydroxide may be used, depending on the food and process.
• For magnesium fortification: other magnesium salts such as magnesium hydroxide, magnesium chloride, or magnesium sulphate are common options.

How is Magnesium oxide made?

Magnesium oxide is produced by heating magnesium compounds until they release water or carbon dioxide, leaving behind MgO. In practice, manufacturers calcine (strongly heat) magnesium hydroxide or magnesium carbonate to make the oxide.³ Industrially, the starting material can come from natural magnesite (a magnesium carbonate ore) or from seawater or brines, where magnesium hydroxide is first precipitated and then calcined to MgO.⁴

Is Magnesium oxide safe to eat?

When used in line with good manufacturing practice, magnesium oxide is “generally recognized as safe” (GRAS) in the United States for use as a pH control agent and nutrient supplement.¹ In the EU, it is an authorized additive with established identity and purity specifications as E530.² The small amounts used in foods are considered safe for the general population.

Does Magnesium oxide have any benefits?

As a fortificant, magnesium oxide can help supply magnesium, an essential mineral that supports nerve and muscle function, normal heart rhythm, and bone health.⁵ Most healthy people get enough magnesium from food, but fortified products and supplements can help close gaps when diets fall short.⁵

Who should avoid Magnesium oxide?

• People with kidney disease should be cautious with magnesium-containing supplements and medications, including magnesium oxide, because their bodies may not clear excess magnesium well.⁵
• Large supplemental amounts of magnesium (from any magnesium salt) can cause diarrhea and cramping; this is not an issue at the small levels typically used in foods.⁵ If you take prescription medicines, ask your clinician or pharmacist about timing, as magnesium supplements can affect the absorption of some drugs.

Myths & facts

• Myth: “Magnesium oxide is the same as Epsom salt.” Fact: Epsom salt is magnesium sulphate; magnesium oxide is a different compound.
• Myth: “It’s a preservative.” Fact: Magnesium oxide is used for pH control and as a magnesium source, not to preserve foods.
• Myth: “It’s synthetic.” Fact: MgO is an inorganic mineral oxide that can be made from natural sources like magnesite or seawater-derived magnesium.

Magnesium oxide in branded foods

Look for “magnesium oxide” or “E530” on ingredient lists. You’ll most often find it in multivitamin/mineral tablets, powdered nutrition drinks, and some fortified foods. It is used at very low levels, so it does not change the taste.

References

Footnotes

1. 21 CFR 184.1431 Magnesium oxide — U.S. Food and Drug Administration (ECFR). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-184/subpart-B/section-184.1431 ↩ ↩²

2. Commission Regulation (EU) No 231/2012 (food additive specifications) — European Union. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩²

3. Magnesium oxide — PubChem, National Center for Biotechnology Information (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/Magnesium-oxide ↩

4. Magnesium Compounds (Mineral Commodity Summaries) — U.S. Geological Survey. https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-magnesium_compounds.pdf ↩

5. Magnesium Fact Sheet for Consumers — Office of Dietary Supplements, NIH. https://ods.od.nih.gov/factsheets/Magnesium-Consumer/ ↩ ↩² ↩³ ↩⁴