What is E170?

Complete guide to understanding E170 (Calcium Carbonate) – the naturally occurring mineral white food colorant and acidity regulator

The Quick Answer

E170 is calcium carbonate—a naturally occurring mineral compound (CaCO₃) used as a white food coloring, acidity regulator, anti-caking agent, and calcium source in foods. It’s chemically inert limestone or chalk that has been mined and processed for food use. E170 comes in two main forms: E170(i) calcium carbonate (ground limestone/GCC or precipitated PCC) and E170(ii) calcium hydrogen carbonate.

E170 is used to provide white coloring in confectionery, baked goods, and dairy products; to regulate acidity in foods; to prevent caking in powdered foods; and to fortify foods with dietary calcium. It’s the mineral that gives flour its white color and is a common ingredient in antacids and calcium supplements. Unlike synthetic or plant-based colorings, E170 is simply ground mineral—chemically inert and biologically very well tolerated.

E170 is FDA-approved (GRAS status) and EU-authorized as a safe food additive with no documented adverse effects at approved levels. The Acceptable Daily Intake is “not specified,” indicating extremely low toxicological concern. Most calcium carbonate passes through the digestive system unchanged; absorbed calcium contributes to normal dietary intake, making this one of the safest and most natural food additives available.

What Exactly Is It?

E170 is calcium carbonate—a naturally occurring white mineral composed of calcium and carbonate ions (Ca²⁺ and CO₃²⁻) in a 1:1 ratio, arranged in crystalline solid form. It’s the same mineral that forms limestone, chalk, marble, and seashells. The food-grade version is obtained either by grinding high-purity limestone deposits (ground calcium carbonate—GCC) or through controlled precipitation from calcium and carbonate salts (precipitated calcium carbonate—PCC).

Think of E170 as refined, purified chalk or limestone—the same mineral used in nature to build shells, corals, and limestone cliffs. It’s chemically inert, meaning it doesn’t react with food components under normal conditions. Your digestive system handles it the same way it handles calcium from any other source: most passes through unchanged, some is absorbed as dietary calcium, and excess is excreted.

Key characteristic: E170 is truly natural—it’s a mineral extracted from the earth, not synthetically manufactured. It’s arguably the most “natural” and safest food colorant available. Because it’s chemically inert, biologically well-tolerated, and passes through the digestive system mostly unchanged, it’s suitable even for sensitive populations including infant formula (with recent EFSA assessment ongoing).

Chemical identity:

• Molecular composition: CaCO₃; one calcium ion (Ca²⁺) bonded to one carbonate ion (CO₃²⁻)
• Molecular weight: 100.09 g/mol
• Crystal forms (polymorphs): Calcite (most common), aragonite, vaterite (all same chemical formula, different crystal structure)
• Thermal properties: Decomposes at temperatures above 800°C releasing CO₂ and calcium oxide (CaO)
• Acid reactivity: Reacts with acids releasing carbon dioxide (CO₂) gas; slightly soluble in acidic solutions
• Inorganic salt: Not metabolized; passes through digestive system largely unchanged

How it’s sourced/made:

E170 is obtained through two primary methods from natural mineral sources:

• Ground Calcium Carbonate (GCC): Mined from high-purity limestone deposits, ground to powder size, purified
• Precipitated Calcium Carbonate (PCC): Produced by reaction of calcium salt (calcium hydroxide or chloride) with carbonate salt, allowing crystals to precipitate and crystallize under controlled conditions
• Primary sources: Limestone deposits, marble quarries, chalk deposits, seashells (in some applications)
• Purification: Products refined to food-grade specifications with strict limits on heavy metals (lead, cadmium, aluminum) and other impurities
• Natural process: Both GCC and PCC use only physical grinding or natural chemical precipitation; no synthetic synthesis

Naturally-derived: E170 is entirely naturally-derived—it’s a mineral extracted from the earth and purified, not synthetically manufactured. This is one of the key distinctions making it one of the most “natural” food additives available.

E170(i) vs E170(ii)

Where You’ll Find It

E170 appears in foods as a white colorant, acidity regulator, or calcium source:

Primary Food Applications:

• Flour (MAJOR USE) – standard practice to whiten flour; nearly all milled bread flours contain E170
• Confectionery and candy (MAJOR USE) – white coating, filling, or coloring in chocolates, jellies, fondants
• Baked goods – cakes, pastries, cookies; white coloring for frostings, icings, decorations
• Dairy products – yogurt, cheese, ice cream; white coloring or calcium enrichment
• Antacids and calcium supplements – primary active ingredient in many antacid tablets
• Powdered foods – anti-caking agent in spice blends, powdered drinks, nutritional powders
• Beverages – cloudy white appearance in some drinks; acidity regulation
• Canned fruits and vegetables – preservative and firming agent
• Chocolate coatings – white chocolate or light-colored coatings
• Supplements and fortified foods – calcium fortification in fortified foods
• Pharmaceutical tablets and capsules – filler, binding agent, color

Regulatory scope: EU Authorization—E170 approved under Regulation (EC) No 1333/2008 as a food additive and colorant; permitted in essentially any food type at “quantum satis” (as much as needed). FDA—Calcium carbonate recognized as GRAS (21 CFR §184.1191); permitted in foods under good manufacturing practice.

Primary food applications: E170 is most extensively used in flour (where it’s the standard whitening agent for most commercial bread flours) and in confectionery (where it provides white color to candies and chocolate products).

Why Do Food Companies Use It?

E170’s primary functions are providing natural white coloring, regulating acidity, preventing caking, and providing nutritional calcium.

Food manufacturers use calcium carbonate for multiple strategic advantages:

• Natural white color: Bright white pigment from natural mineral source
• Flour brightening: Standard practice in flour production; improves appearance and consumer appeal
• Acidity regulation: Neutralizes excess acidity; acts as buffer to stabilize flavor and texture
• Anti-caking agent: Prevents clumping in powdered foods and spice blends
• Calcium fortification: Adds nutritional calcium to foods and supplements
• Texture improvement: Acts as firming agent in canned fruits and vegetables
• Cost efficiency: Inexpensive mineral; abundant natural source
• Regulatory acceptance: FDA GRAS status; EU-approved; safe status worldwide
• Natural origin: Mineral-based; appeals to “natural” and “clean label” positioning
• Multifunctional: Serves multiple purposes (color, acidity regulation, anti-caking) simultaneously
• Stability: Chemically stable; doesn’t degrade during storage or processing
• Safety profile: Extremely well-tolerated; suitable even for sensitive populations
• No flavor impact: Odorless and tasteless; doesn’t affect food taste

Unique advantage: E170 is one of the few food additives that serves BOTH cosmetic purposes (white coloring) AND nutritional/functional purposes (acidity regulation, calcium fortification), making it economically and functionally valuable.

Is It Safe?

E170 is safe at food use levels and has an excellent safety record with no documented adverse effects at approved levels.

Regulatory approval:

• FDA status (US): GRAS (Generally Recognized as Safe) under 21 CFR §184.1191; approved for use in foods
• EU authorization: E170 approved as food additive under Regulation (EC) No 1333/2008
• EFSA evaluation: Re-evaluated in 2011 and 2023; approved; minimal safety concerns identified (aluminum contamination noted as area requiring attention)
• JECFA status: Recognized as safe with ADI “not limited”
• International approval: Approved by regulatory bodies in Australia, New Zealand, and internationally

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
• Not absorbed: Poorly absorbed; most passes through digestive system unchanged
• Absorbed calcium contribution: Absorbed calcium contributes to normal dietary intake (positive aspect)
• Body regulation: Body regulates calcium absorption; excess is safely excreted via urine or feces
• Chemically inert: Doesn’t react with food or body tissues under normal conditions
• ADI not specified: Indicates very low toxicological concern; essentially unlimited safe use at food levels
• Long history of safe use: Consumed for thousands of years; modern food use for centuries
• Multiple regulatory approvals: Recognized as safe across EU, FDA, and other jurisdictions
• Suitable for sensitive groups: Safe for children, pregnant women, and various dietary restrictions
• No documented harm: Despite centuries of use and worldwide approval, no safety concerns have emerged

Noted concerns:

• Aluminum contamination: EFSA noted that trace aluminum contamination in some E170 sources is a concern that should be addressed through stricter purity specifications; this is quality control issue rather than inherent safety concern with calcium carbonate itself
• Excessive intake concern: Consuming excessive amounts from supplements could theoretically cause hypercalcemia; however, this is not a food use concern, only relevant for extreme supplement overconsumption

Health Aspects Beyond Coloring

E170 provides nutritional and health benefits beyond its coloring function:

• Dietary calcium source: Contributes to daily calcium intake; important for bone health
• Acidity neutralization: Acts as antacid; relieves gastric hyperacidity and indigestion
• Mineral nutrition: Absorbed calcium contributes to normal calcium metabolism
• Buffer effect: Stabilizes pH in foods; reduces need for other acidity regulators
• Bone health support: Dietary calcium essential for bone maintenance and strength
• Safe fortification: Used to fortify foods with calcium for populations with inadequate intake

The Bottom Line

E170 (calcium carbonate) is a naturally occurring white mineral used as a food colorant, acidity regulator, anti-caking agent, and calcium source in foods. It’s ground limestone or precipitated calcium—chemically inert and biologically well-tolerated. It’s the same mineral that forms seashells, limestone cliffs, and chalk.

E170 is approved by regulatory authorities worldwide and has an excellent safety record.

Key advantages: E170 is safe at food use levels. FDA GRAS status; EU-authorized; EFSA-approved. No documented adverse effects. Poorly absorbed; most passes through digestive system unchanged. Chemically inert and stable. Suitable for sensitive populations including children and pregnant women. Naturally-derived from mineral sources. Multifunctional (color, acidity regulation, calcium fortification). ADI “not specified” indicating very low toxicological concern. Used for thousands of years with excellent safety record.

For consumers: E170 is safe and beneficial when encountered in food products. This is a naturally occurring mineral—literally chalk or ground limestone. It’s not absorbed significantly, meaning it mostly passes through your system unchanged. The small amounts that are absorbed contribute to your dietary calcium intake. Unlike many food additives that are synthetic chemicals, E170 is a mineral that humans have safely consumed for millennia. It’s one of the safest and most natural food additives available.

Primary application: E170 is iconic in flour (where it’s the standard whitening agent), antacids (where it’s the active ingredient), and confectionery (where it provides white color). Nearly all commercial bread flour contains E170 as the whitening agent, making it one of the most widely consumed food additives globally.

Natural perspective: E170 is among the most genuinely “natural” food additives available. It’s not synthetically manufactured but rather extracted and purified from mineral deposits. It’s chemically identical to chalk, limestone, marble, seashells, and coral. It’s been safely used by humans for thousands of years—from chalk for writing to limestone for construction to the mineral in your dietary calcium supplements.