E172 – Iron oxides and hydroxides

General Information

Iron oxides and hydroxides (food additive E172) are additives known as iron oxides or iron pigments. In the food industry, they are classified as colorants and are used to give products shades of red, yellow, or black. The main purpose of the colorant E172 is to make products more visually appealing to consumers.

Iron oxides occur naturally, but for food use they are mostly produced synthetically to ensure color stability and purity. Historically, iron pigments were used in antiquity for coloring ceramics and cosmetics, while in the food industry E172 colorants began to be used in the 20th century.

The chemical formula of the additive depends on the specific form of iron oxide present. According to the international standard Codex Alimentarius CXG 36-1989, food additive E172 (iron oxides and hydroxides) is subdivided into the following subtypes:

• INS 172(i) — black iron oxide (Fe₃O₄)
• INS 172(ii) — red iron oxide (Fe₂O₃)
• INS 172(iii) — yellow iron oxide (FeO(OH) or hydrated iron oxide)

Each of these subtypes has different physical properties and colors, making them suitable for use as natural mineral colorants in the food, pharmaceutical, and cosmetic industries.

In EU Regulation No. 1333/2008, all these compounds are grouped under the general code E172 without specifying subclasses. This approach simplifies classification for the EU market, while the Codex Alimentarius system allows more precise differentiation of iron oxide color variants for international use.

Physically, iron oxides are powdery substances with low solubility in water and are stable to heat and light.

For the food industry, additive E172 is obtained by controlling the oxidation of iron or by extracting and purifying natural iron oxides, which are then ground into a fine powder suitable for addition to foods.

Effects on the Body

Benefit of Additive E172

Food additive E172 contains iron, an element essential for the synthesis of hemoglobin and enzymes, although the amount present in food colorants is too small to provide significant nutritional benefit.

The main benefit of the additive is visual appeal, which stimulates appetite and enhances food perception. EFSA in its assessments confirms that when used in permitted amounts, colorant E172 does not pose a health risk, and JECFA notes that iron-containing colorants do not require an ADI due to low toxicity.

Risks of Additive E172

Food additive E172 is almost insoluble in the stomach, passing through the digestive tract without significant absorption. Potential risks may occur only with excessive consumption well above typical dietary doses. In such cases, minor gastrointestinal irritation or long-term iron accumulation may be possible.

EFSA and JECFA confirm that under normal use, colorant E172 is safe, and the FDA also recognizes it as safe when meeting technical standards and product purity. An ADI is not established for E172 due to low toxicity and minimal bioavailability of iron from the colorant.

Uses

In the food industry, additive E172 is used as a colorant for chocolate, candies, biscuits, cakes, ice cream, jelly, and various confectionery products.

Iron oxides are also used for coloring tablet coatings and vitamin supplements.

EFSA notes that colorant E172 is stable during heating and storage, and JECFA emphasizes that its use is limited to technological needs, i.e., to achieve the desired color only.

The FDA emphasizes that E172 should only be used in products where it serves a technological function as a colorant, and excess should not exceed the level necessary to achieve the desired color. This ensures safe consumption and prevents potential iron overaccumulation.

Legal Status

In the EU, food additive E172 is permitted in all food products according to Regulation (EU) No. 1333/2008 with compliance to technological requirements.

In Ukraine and most European countries, the colorant is also permitted. In the USA, the FDA allows E172 as a food colorant provided it meets purity and technological standards. In Japan and Canada, its use is regulated similarly, with restrictions on product quality and purity.