What is E505?

Complete guide to understanding E505 (Ferrous Carbonate) in your food

The Quick Answer

E505 is ferrous carbonate, an iron-containing food additive.

It’s primarily used in food to fortify products with iron, helping prevent iron deficiency anemia.

It’s also approved as an acidity regulator in some food applications.

📌 Quick Facts

Category: Nutrient supplement and acidity regulator
Found in: Infant formula, fortified cereals, vitamin supplements, dietary products
Safety: Generally Recognized As Safe (GRAS) – Approved by regulatory bodies
Approved by: FDA (USA), EFSA (Europe), and food authorities worldwide
Chemical formula: FeCO3
Key benefit: Provides bioavailable iron for fortification

What Exactly Is It?

E505 is made from iron in its ferrous (iron II) form combined with carbonate.

The chemical formula is FeCO3, with a molecular weight of 115.85 g/mol.

It occurs naturally as a mineral but is typically synthesized for food use through chemical processes.

In technical terms, it’s an iron(II) salt used primarily as a nutrient source rather than as a traditional food additive like preservatives or emulsifiers.

Where You’ll Find It

E505 appears primarily in nutritional and fortified products:

• Infant formula and baby food
• Fortified breakfast cereals
• Vitamin and mineral supplements
• Dietary supplements for iron deficiency
• Fortified flour and grain products
• Some dairy products
• Animal feed (for livestock)

It’s not commonly found in typical everyday processed foods.

It’s mainly used in products specifically designed for nutritional fortification.

💡 Pro Tip: Check the ingredient lists of infant formula, cereals, and vitamin supplements for “E505”, “ferrous carbonate”, or “iron carbonate”. It’s often used in products targeting iron-deficient populations.

Why Do Food Companies Use It?

E505’s main function is iron fortification: it adds bioavailable iron to foods.

Iron deficiency is a global health concern, particularly affecting:

• Infants and young children
• Pregnant women
• People with anemia
• Vegetarians and vegans (who may have lower dietary iron)

E505 is added to products to help prevent and treat iron-deficiency anemia by providing iron that the body can absorb and use to make hemoglobin—the protein in red blood cells that carries oxygen.

When used as an acidity regulator, it helps neutralize acidic conditions in certain food products.

Is It Safe?

E505 is recognized as safe by major regulatory authorities.

The FDA lists ferrous carbonate as Generally Recognized As Safe (GRAS) for use as a nutrient supplement and in infant formula.

The EFSA has evaluated iron compounds and established safe maximum iron content levels in feed and food products.

Safe iron intake levels:

• The European Food Safety Authority (EFSA) notes that iron has a Provisional Maximum Tolerable Daily Intake of 0.8 mg/kg body weight based on studies in animals.
• For most people, normal dietary intake is well below potentially harmful levels.
• Excessive iron supplementation can cause problems, but normal food fortification levels are carefully controlled.

E505 has poor bioavailability in some animals (like cats and dogs) but is considered appropriate for human use, particularly in infant formula where bioavailability is important for iron absorption.

⚠️ Important Note: While E505 is safe in approved food applications, iron supplements should only be taken under medical supervision. Some individuals, particularly those with hemochromatosis (iron overload disorder), should avoid excess iron. If you have concerns about iron levels or are using iron supplements, consult your healthcare provider.

Natural vs Synthetic Version

E505 is synthesized for food use rather than extracted from natural sources:

Natural origin: Ferrous carbonate occurs naturally as a mineral (siderite), but this natural form is not used directly in food due to purity and quality control concerns.

Synthetic version: Made through controlled chemical processes to ensure purity and bioavailability, typically by reacting iron compounds with carbonates.

The synthetic version provides better quality control and consistent iron content, making it more suitable for pharmaceutical and food fortification applications.

Natural Alternatives

Want to avoid E505 or get iron from other sources?

Food companies and consumers can use these alternatives:

• Ferrous sulfate (E1) – Another iron salt, often used in feed and fortification
• Ferrous gluconate (E579) – Iron combined with gluconic acid, sometimes used in food fortification
• Ferric oxide (E172) – Iron oxide used in some fortified products
• Dietary sources – Red meat, poultry, fish, beans, lentils, spinach, fortified cereals

Some of these alternatives have different bioavailability profiles and may be preferred depending on the food matrix and intended use.

The Bottom Line

E505 (ferrous carbonate) is an iron compound used to fortify foods with this essential nutrient.

It’s found primarily in infant formula, dietary supplements, and fortified grain products.

Regulatory bodies including the FDA and EFSA have determined it’s safe for use in approved applications.

Unlike many food additives that enhance taste or texture, E505 serves a genuine nutritional purpose by helping prevent iron deficiency—a significant global health issue.

If you’re concerned about iron intake, whether too much or too little, discuss it with your healthcare provider rather than self-supplementing.

What is E505? – Complete guide to understanding Ferrous Carbonate in your food