What is E528?

Complete guide to understanding magnesium hydroxide in your food

The Quick Answer

E528 is magnesium hydroxide, a naturally occurring mineral used as a food additive.

It’s used to regulate acidity, prevent clumping in powders, and stabilize food products.

Most people consume it regularly in items like cheese, canned vegetables, dairy products, and processed foods.

What Exactly Is E528?

E528 is magnesium hydroxide (Mg(OH)₂), a white powder derived from the natural mineral brucite.

Brucite is a naturally occurring mineral found in serpentinite deposits and metamorphic rocks throughout the Earth. Notable deposits exist in the Ural Mountains (Russia), California (USA), Italy, and Greece. When you see “brucite” mentioned, it’s referring to magnesium hydroxide in its natural mineral form.

Most people know magnesium hydroxide by another name: “milk of magnesia,” the suspension form used as an antacid and mild laxative. E528 is the same chemical compound used in food applications.

In technical terms, magnesium hydroxide is an alkaline (opposite of acidic) compound with very low water solubility. But for food consumers, what matters is that it’s a naturally derived, long-approved additive.

Where You’ll Find E528

E528 appears in numerous dairy, processed, and prepared foods:

– Cheese and cheese products
– Canned vegetables
– Dairy products and powdered milk
– Juice and soft drinks
– Jams and candies
– Ice cream and frozen desserts
– Bakery and pastry products
– Table salt
– Spices and seasonings
– Processed meats and fish
– Soups and broths
– Rice and pasta
– Food supplements

If you’ve eaten packaged or processed food, you’ve almost certainly consumed trace amounts of E528.

Why Do Food Companies Use E528?

E528 serves four key functions in food manufacturing.

First, it’s a powerful acidity regulator. By neutralizing acids, it adjusts pH to ideal levels, extending shelf life and preventing the acrid taste that comes from excessive acidity. In juice drinks, for example, E528 prevents overly acidic products from irritating the mouth and digestive tract while preventing microorganism growth.

Second, it prevents clumping. In powdered foods like milk powder, salt, and spice mixes, E528 absorbs moisture and prevents granules from sticking together—critical for products to remain free-flowing in storage.

Third, it acts as a stabilizer and curing agent. In jams, candies, and ice cream, it reacts with polysaccharides and fats to create stable complexes that prevent separation, precipitation, and stratification.

Fourth, it preserves color and texture. By regulating pH, it maintains the natural color of foods and prevents degradation.

So food manufacturers use E528 because it solves real production problems while being natural, safe, and inexpensive.

Is It Safe?

Regulatory authorities confirm E528 is safe for food use.

The FDA classifies it as “Generally Recognized As Safe” (GRAS). The EFSA recently approved it in March 2024 through Regulation (EU) No 2024/836. WHO’s JECFA also approved it. Toxicological studies show no carcinogenicity, no reproductive/developmental toxicity, and no genotoxicity (genetic damage).

At food additive levels—meaning trace amounts in finished products—E528 is completely safe for all populations, including children and pregnant women. Moderate consumption causes no adverse reactions.

E528 is used under “Quantum Satis” authorization, meaning manufacturers use only the necessary amount with no absolute maximum specified, reflecting confidence in its safety.

Understanding E528’s Two Faces: Food Additive vs. Medicine

It’s crucial to understand the difference between food additive and medication doses.

At Food Additive Levels (Trace Amounts)

No documented side effects. The tiny amounts in cheese, vegetables, and powdered foods are completely safe for all populations.

At Therapeutic Doses (Medication/Laxative)

Side effects occur because the doses are vastly higher—2.4 to 4.8 grams produces intended laxative effects:

– Loose or watery stools (intended effect)
– Stomach cramping and discomfort
– Mild nausea and queasiness
– Bloating and gas

These effects are mild and reversible, usually fading within hours. This is why magnesium hydroxide is safely sold over-the-counter for occasional constipation (no more than 3 consecutive days).

At Extremely High Overdose Levels (>30 grams)

Serious medical complications can occur:

– Hypermagnesemia (dangerous blood magnesium elevation)
– Severe diarrhea and dehydration
– Muscle weakness
– Irregular heartbeat
– Confusion and drowsiness
– In extreme cases: respiratory depression or cardiac arrest

These extreme effects only occur from overdose and are not relevant to food additive consumption.

Who Should Avoid High-Dose Magnesium Hydroxide (Not Relevant to Food Additive Use)

Certain groups face higher risks when taking magnesium hydroxide as a medication—NOT as a food additive:

– People with kidney disease (cannot excrete excess magnesium)
– Those with heart disease or irregular heartbeats
– People with digestive disorders like Crohn’s disease
– Anyone taking medications that interact with magnesium
– Those severely dehydrated

At food additive levels, these precautions don’t apply.

Natural Occurrence and Brucite

E528 comes directly from nature.

Magnesium hydroxide occurs naturally as the mineral brucite, formed when magnesium-rich rocks (like serpentinite) undergo geological alteration. Most food-grade E528 is extracted directly from brucite deposits through grinding and purification, making it a minimally processed natural substance.

Alternatively, it’s produced by extracting magnesium from seawater (600 cubic meters of seawater yields about 1 tonne of magnesium hydroxide) using calcium hydroxide to precipitate it out. This industrial process is still based on natural sources and is similar to other food ingredient extraction.

Historical Use

Magnesium hydroxide isn’t a new chemical. It’s been used medicinally for over a century. “Milk of magnesia” suspensions have been sold as over-the-counter antacids and laxatives since the 1800s. This long history of safe medical use supports its approval for food applications.

Natural vs. Synthetic E528

Modern E528 is neither purely “natural” nor purely “synthetic.”

It’s extracted and purified from natural minerals (brucite) or produced through industrial precipitation from seawater. Both processes yield chemically identical magnesium hydroxide, and your body processes it identically regardless of source.

The key distinction is that it comes from natural materials rather than being chemically synthesized from unrelated compounds.

Handling, Storage, and Contaminant Concerns

Food-grade E528 must meet strict purity standards.

It must be stored in dry, closed containers to prevent moisture absorption. A critical quality concern: some natural brucite deposits may contain asbestos fibers. Food-grade E528 undergoes testing to ensure asbestos-free status, with manufacturers implementing quality controls to address this issue.

Heavy metal limits are strictly enforced—lead maximum 10 ppm, arsenic maximum 3 ppm—meeting food safety regulations.

Vegan, Vegetarian, and Allergen Status

E528 is suitable for:

– Vegan diets ✓
– Vegetarian diets ✓
– Gluten-free diets ✓
– Those with most allergies ✓

Magnesium hydroxide is mineral-derived with no animal products or animal byproducts involved in its production.

Recent Regulatory Approval

E528 received formal EU approval in March 2024.

The European Commission issued Regulation (EU) No 2024/836, officially approving magnesium hydroxide E528 as an alkaline substance for food use. This recent approval reflects modern food safety assessment and confirms regulatory confidence in its safety profile.

The Bottom Line

E528 (magnesium hydroxide) is a naturally derived mineral additive used to regulate acidity and prevent clumping in foods.

Regulatory authorities worldwide classify it as safe at food additive levels.

At trace amounts found in cheese, vegetables, juice, and other processed foods, it poses no documented health risks to any population.

The digestive side effects E528 is known for (as milk of magnesia laxative) only occur at much higher therapeutic or medication doses—not at food additive concentrations.

Its long history of safe medical use, recent EU approval, and rigorous food safety standards support its safety in food applications.

As always, food labels must declare E528 by name, so you can make informed dietary choices.