E172II - Red iron oxide

At a glance

• What it is: a red inorganic pigment, chemically iron(III) oxide (Fe2O3)
• What it does: colors foods and coatings in red to reddish-brown hues
• Appearance: fine, red powder; practically insoluble in water
• Stability: highly stable to heat, light, and pH in typical food use
• Regulatory note: part of the E172 family of iron oxides and hydroxides in the EU; U.S. allows only very limited food uses for synthetic iron oxide
• Typical uses: confectionery coatings, decorative elements, and some capsule or tablet coatings

Why is Red iron oxide added to food?

Food makers use red iron oxide when they need a durable red or brick-red shade that won’t fade during cooking, baking, drying, or storage. Because it is mineral-based and insoluble, it disperses as tiny colored particles rather than dissolving, which helps it keep a consistent hue even in challenging processes.

What foods contain Red iron oxide?

You are most likely to see red iron oxide in:

• Sugar-coated sweets and dragees
• Decorative toppings and coatings for bakery items
• Outer coatings of some dietary supplement tablets and capsules

In the EU, red iron oxide is listed within the E172 group for use as a color in specific categories and at set maximum levels. In the United States, synthetic iron oxide is permitted only for very limited food uses (for example, certain sausage casings) rather than as a general-purpose food color.¹

What can replace Red iron oxide?

Alternatives depend on the target shade, processing, and labeling goals:

• For warm red/orange tones: paprika extract or annatto
• For bright red: cochineal or beetroot red in suitable applications
• For non-red coverage/opacity: titanium dioxide for white, where allowed

Natural colors can be less heat- and light-stable and may shift hue with pH, so formulators choose replacements based on performance needs.

How is Red iron oxide made?

Food-grade red iron oxide is produced synthetically from iron salts. A typical process precipitates hydrated iron oxides from solution and then dehydrates or calcines them to form iron(III) oxide, with tight controls on purity and particle characteristics.² The specification also sets impurity limits (for example, for heavy metals) to ensure the material meets food-additive standards.² Chemically, the colorant is Fe2O3, a stable, water-insoluble pigment.³

Is Red iron oxide safe to eat?

EFSA (European Food Safety Authority) evaluated the iron oxides and hydroxides group (E172) and concluded there is no safety concern for their use as food additives at reported use levels. Absorption from the gut is very low, and no genotoxicity was identified.⁴ In the U.S., FDA permits synthetic iron oxide only for specific, restricted food uses, which also reflects a conservative approach to exposure.¹

Does Red iron oxide have any benefits?

Its main benefit is technical: reliable color that resists fading under heat, light, and during storage. It is not used as a source of dietary iron, and it does not meaningfully contribute to iron intake in typical uses.

Who should avoid Red iron oxide?

Most people do not need to avoid red iron oxide. Individuals with rare iron overload conditions may be cautious about iron sources, but red iron oxide is poorly absorbed and is not intended to raise iron levels.⁴ If you are following guidance to avoid certain color additives for personal or medical reasons, check labels for “iron oxides,” “E172,” or “iron(III) oxide.”

Myths & facts

• “It’s just rust.” Partly true in chemistry, but food-grade red iron oxide is manufactured under strict specifications and purified for safety and consistency—not scraped from rusty metal.
• “It works like an iron supplement.” False. The pigment is poorly absorbed and used only for color, not nutrition.
• “It always replaces natural reds.” False. Formulators may choose mineral colors like E172 for stability, but natural reds such as beetroot red or annatto are also common when they fit the product’s needs.

Red iron oxide in branded foods

On ingredient lists, look for “E172,” “iron oxides,” “iron(III) oxide,” or “ferric oxide.” You’ll most often find it in the outer layers of products—like the colored shell of a dragee or the coating on a tablet or capsule—rather than in the food matrix itself. Some brands may switch between mineral reds and natural reds depending on season, supply, and desired shade, so labels can vary.

References

Footnotes

1. 21 CFR 73.200 — Iron oxides, synthetic (color additive for foods, limited uses) — U.S. FDA. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-A/part-73/subpart-A/section-73.200 ↩ ↩²

2. Commission Regulation (EU) No 231/2012 — Specifications for food additives. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩²

3. Iron(III) oxide — PubChem Compound Summary (identity/properties). https://pubchem.ncbi.nlm.nih.gov/compound/Iron-_III_-oxide ↩

4. Re-evaluation of iron oxides and hydroxides (E 172) as food additives — EFSA Journal. https://www.efsa.europa.eu/en/efsajournal/pub/4317 ↩ ↩²