What is E172?

Complete guide to understanding E172 (Iron Oxides and Hydroxides) – the mineral-based food colorants

The Quick Answer

E172 is a group of iron oxides and iron hydroxides—inorganic mineral pigments that range in color from yellow to red to black, used as food colorants. Unlike synthetic or plant-based colorings, E172 is made from iron compounds through chemical synthesis starting from iron powder. It comes in three main forms: E172(i) black iron oxide (magnetite), E172(ii) red iron oxide (hematite), and E172(iii) yellow iron oxide (goethite).

E172 is used to color foods surface coatings only—not intended to permeate food, but rather coat the exterior of products like candies, chocolates, pills, and meat products. It’s found in confectionery, bakery coatings, meat pastes, cosmetics, and pharmaceuticals. Unlike synthetic dyes, iron oxides are essentially inert minerals—the iron is not absorbed by the body and passes through the digestive system unchanged.

E172 is FDA-approved and EU-authorized as a safe food coloring with an Acceptable Daily Intake (ADI) of 0.5 mg/kg body weight. It has an excellent safety record with no documented adverse effects at approved levels. Iron oxides have been used in paints, coatings, and pigments for thousands of years—their use in food is merely one modern application of this stable, naturally-occurring mineral compound.

What Exactly Is It?

E172 is a group of inorganic pigments composed of iron oxides and hydroxides—chemical compounds of iron and oxygen that form stable, colored mineral powders. These are not naturally extracted from ore but rather synthetically produced from iron powder through controlled chemical reactions.

Think of E172 as refined mineral pigments. Iron oxides are among the oldest pigments used by humans—prehistoric cave paintings used natural iron oxide pigments ~15,000 years ago. The compounds are chemically stable, inert in the body (not absorbed), and essentially pass through the digestive system unchanged.

Key characteristic: E172 is fundamentally different from synthetic dyes or even plant-based colorings. It’s an inorganic mineral pigment. The iron is not bioavailable—your body doesn’t absorb it as nutritional iron. It’s used ONLY for surface coating, not interior coloring, limiting exposure even further. The compounds are among the most chemically stable and safe colorants available.

Chemical identity:

• E172(i) – Black Iron Oxide: Fe₃O₄ (Iron(II,III) oxide, magnetite); ferric/ferrous mixed compound
• E172(ii) – Red Iron Oxide: Fe₂O₃ (Iron(III) oxide, hematite); ferric iron compound
• E172(iii) – Yellow Iron Oxide: FeOOH (Iron(III) oxyhydroxide, goethite); ferric hydroxide compound
• Crystal phases: Magnetite (black), Hematite (red), Goethite (yellow) are specific mineral crystal forms
• Molecular structure: Three-dimensional crystalline lattices of iron and oxygen atoms
• Bioavailability: Iron in E172 is not bioavailable; not absorbed by intestines

How it’s made:

E172 is produced through synthetic chemical synthesis from iron powder:

• Starting material: Iron powder (reduced iron metal)
• Chemical reactions: Iron oxidized under controlled conditions (temperature, oxygen, acid/base conditions)
• Synthesis from sulfate: Iron sulfate can be oxidized to produce iron oxides
• Synthesis from chloride: Iron chloride can be oxidized to produce iron oxides
• Controlled oxidation: Different oxidation rates and conditions produce different crystal phases (black/red/yellow)
• Crystallization: Products crystallized under controlled conditions to achieve desired color and pigment properties
• Purification: Products refined and purified to food-grade specifications with minimal metal contamination
• Not naturally extracted: Commercial food-grade E172 is NOT mined as natural ore but rather synthetically produced

E172(i) vs E172(ii) vs E172(iii)

Where You’ll Find It

E172 appears in foods where surface coating coloring is needed:

Primary Food Applications:

• Confectionery and candy (MAJOR USE) – chocolate coatings, candies, jellies; surface coloring
• Cakes and desserts (MAJOR USE) – cake decorations, dessert coatings; surface coloring
• Meat products – meat pastes, sausage casings, salmon pastes, shrimp pastes; color enhancement
• Black olives – green olives artificially darkened with E172(i) for color consistency
• Cheese rind – colored surface coatings
• Chocolate and chocolate products – coating agent for chocolate-covered items
• Baked goods – surface coatings and decorations
• Pharmaceutical tablets and capsules – coloring for identification and aesthetics

Regulatory scope: EU Authorization—E172 approved for use in various food categories; specifically limited to surface coating. FDA—Iron oxides approved as colorants for pharmaceuticals and foods (surface use).

Primary food applications: E172 is most extensively used in confectionery (chocolate coatings, candies) and pharmaceutical tablets where surface coating colorants are essential. It’s also used in meat products for color enhancement and in pharmaceutical applications for color identification.

Why Do Food Companies Use It?

E172’s primary function is providing stable, heat-resistant surface coloring for foods where other colorants might be unsuitable.

Food manufacturers use iron oxides for multiple strategic advantages:

• Stable coloring: Extremely resistant to light, heat, and chemical degradation; colors don’t fade
• Surface coating: Ideal for coating applications where color permeability is not desired
• Heat resistant: Maintains color stability at high temperatures; suitable for baked goods and heat-processed items
• Chemical inert: Doesn’t react with food components; doesn’t affect flavor or taste
• Cost efficient: Relatively inexpensive coloring compared to other options
• Regulatory acceptance: EU and FDA approved; long history of safe use
• Not absorbed: Unlike some food colorants, iron is not absorbed by body; minimal systemic exposure
• Broad color range: Available in black, red, and yellow; can be mixed for intermediate shades
• Cosmetic enhancement: Improves visual appeal of foods and pharmaceuticals
• Meat product coloring: Artificial coloring of meat products (salmon pastes, sausage casings) for appearance consistency
• Consistency: Provides consistent coloring in commercial production vs. natural color variation

Unique advantage: E172 is one of the few food colorants that is truly inert—not metabolized, not absorbed, not systemically available. It’s essentially a mineral pigment that passes through the digestive system unchanged.

Is It Safe?

E172 is safe at food use levels and has an excellent safety record.

Regulatory approval:

• EU authorization: E172 approved as food colorant; permitted in various food categories (surface coating)
• FDA status (US): Approved as food coloring; recognized as safe for food and pharmaceutical use
• EFSA evaluation: Evaluated and approved; safety assessments completed
• JECFA status: Recognized as safe
• International approval: Approved by regulatory bodies worldwide

Safety profile:

• No acute toxicity: No documented toxicity at food use levels
• No chronic toxicity: Long-term consumption shows no harm
• No adverse effects: No documented adverse health effects in any population
• No carcinogenicity: No evidence of cancer-causing potential
• No reproductive/developmental effects: Safe for pregnancy and breastfeeding
• No genotoxicity: No evidence of genetic damage
• No absorption: Iron in E172 is NOT absorbed by intestinal mucosa; passes through unchanged
• Non-bioavailable: Unlike iron supplements, iron from E172 cannot be utilized by body as nutritional iron
• Inert mineral: Chemically stable and inert; doesn’t react with food or body tissues
• No interactions: Doesn’t interfere with other nutrient absorption or medication efficacy
• ADI established: 0.5 mg/kg body weight per day—conservative safety margin applied
• Surface use only: Limited to surface coating, reducing exposure vs. interior colorants
• Long history of safe use: Used in paints and pigments for thousands of years; additive food use for decades
• Multiple regulatory approvals: Recognized as safe across EU, FDA, and other jurisdictions
• No documented harm: Despite extensive use, no safety concerns have emerged

Noted concerns:

• Aluminum contamination: Some sources note possible trace aluminum contamination that may not be labeled; EFSA has noted this should be addressed in specifications
• Manufacturing supply: VENATOR is the primary/sole commercial manufacturer; supply disruptions could impact market availability
• Particle size concerns addressed: Food-grade E172 is NOT a nanoparticle according to EFSA assessment; constituent particles typically larger than nano-range

The Bottom Line

E172 (iron oxides and hydroxides) is a group of inorganic mineral pigments used as surface coatings for foods to provide black, red, or yellow coloring. These are chemically stable, non-absorbed compounds that pass through the digestive system unchanged. They are synthetically produced from iron powder, not naturally extracted, and are among the oldest pigments used by humans—prehistoric cave paintings used iron oxide pigments ~15,000 years ago.

E172 is approved by regulatory authorities worldwide and has an excellent safety record.

Key advantages: E172 is safe at food use levels. EU-authorized; FDA-approved; EFSA-evaluated. No documented adverse effects. NOT absorbed by the body; passes through digestive system unchanged. Chemically inert and stable. Resistant to light, heat, and chemical degradation. Used for surface coating only, minimizing exposure. Has been safely used in pigments and paints for thousands of years. Conservative ADI of 0.5 mg/kg established.

For consumers: E172 is safe when encountered in food products. This is a mineral pigment—not a synthetic dye or chemical additive in the traditional sense. The iron is not bioavailable and not absorbed. Your body essentially passes it through unchanged. Unlike some colorants that may be absorbed systemically, E172’s non-absorption property makes it one of the safest food colorants available from a toxicological perspective.

Primary applications: E172 is iconic in chocolate coatings, colored candies, and pharmaceutical tablets where stable, heat-resistant surface coloring is essential. It’s also used in meat products and other foods where color enhancement is desired.

Historical perspective: Iron oxides are not modern inventions—they’ve been used as pigments for thousands of years. Their use in food is merely one application of these stable, naturally-occurring mineral compounds that humans have safely utilized for millennia.