Is Calcium Carbonate (E170) Vegan?

Also known as: Chalk, Limestone, Ground calcium carbonate, Precipitated calcium carbonate, CI 77220

Vegan

Calcium carbonate is vegan. Food-grade E170 comes from quarried limestone, chalk, or marble, or from precipitation of the same mineral. Shell-derived calcium exists in supplements and is always named on the label.

Last checked How we decide

Ingredient Data

Vegan Status

Vegan

E-Number

E170

Also Known As

Chalk; Limestone; Ground calcium carbonate; Precipitated calcium carbonate; CI 77220

Source

Ground rock or a precipitated mineral. Most food-grade material is limestone, chalk, or marble that has been quarried, washed, and milled. The precipitated grade is made by calcining limestone to quicklime, slaking it with water, and recarbonating the result with carbon dioxide, which gives finer and more uniform crystals.

Commonly Found In

White and brown flour in the UK, bread, plant milks and calcium-fortified drinks, tofu, sweets and chewing gum, white food coatings, toothpaste, antacids, and calcium supplements.

Vegan Alternative

No substitute needed. E170 is vegan. In supplements, check that the label does not name oyster shell or coral as the calcium source.

Additional Notes

EU specifications define E170 as calcium carbonate from ground limestone or from precipitation, which keeps shell-derived material outside the additive number. Supplements are the place to look twice: oyster shell calcium and coral calcium are chemically the same compound from an animal source, and both are declared by name. In the UK, calcium carbonate is a legally required addition to most flour.

In depth

Quarried Rock and Precipitated Crystal

Calcium carbonate is one of the most abundant minerals on the planet, laid down as limestone, chalk, and marble. Food and pharmaceutical grades come from selected deposits with low heavy metal content, quarried, washed, dried, and milled to a controlled particle size. The precipitated grade takes an extra loop.

Limestone is heated to drive off carbon dioxide, leaving quicklime; the quicklime is slaked with water to calcium hydroxide; carbon dioxide is bubbled back through the milk of lime, and calcium carbonate drops out as fine, uniform crystals. Manufacturers choose this route when they need a specific particle shape, for toothpaste abrasion or for tablet compression. Both routes are geological in origin. Neither uses an animal-derived reagent, filter, or carrier, and the EU specification for E170 names ground limestone and precipitation as the permitted routes.

The Shell Calcium Exception

Chalk from a cliff and calcium from an oyster shell are the same compound, and both dissolve into the same calcium ions in the stomach. What differs is where they came from. Supplement manufacturers do sell oyster shell calcium, coral calcium, and eggshell calcium, all of which are animal-derived and are not vegan.

All three are declared on the label by name, because those names carry marketing weight and because allergen rules require shellfish to be flagged. A supplement that says only "calcium carbonate" is mineral in normal practice, and one that says "calcium carbonate from oyster shell" is not vegan. Where a label leaves the source open and the answer matters, the manufacturer will confirm it. Food additive use under E170 does not raise the question at all.

Flour, Tofu, and Plant Milk

British law has required calcium carbonate in most flour since 1943, a wartime nutrition measure that survives in the current Bread and Flour Regulations. Wholemeal flour is exempt. That is why a UK bread label may list calcium carbonate with no fortification claim attached. Tofu makers use calcium salts as coagulants, and calcium sulfate is the more common choice, giving firm tofu with a useful calcium content.

Plant milks use calcium carbonate for fortification, which is why an oat or soy drink can match dairy milk for calcium; the mineral settles out, which is why the carton tells you to shake it. Antacids and calcium supplements use the same compound at gram doses. Absorption from calcium carbonate needs stomach acid, so it is best taken with food, while calcium citrate absorbs without that requirement.

Frequently asked questions

Is E170 vegan?

Yes. Food-grade calcium carbonate comes from quarried limestone, chalk, or marble, or from precipitation of the same mineral. EU specifications name those routes, so shell-derived material does not qualify for the number.

Is calcium carbonate made from shells or bones?

The additive is not. Supplements sometimes use oyster shell, coral, or eggshell calcium, and those are animal-derived and named on the label. Bone-derived mineral is a different compound, calcium phosphate, sold as E542 bone phosphate.

Is the calcium in plant milk vegan?

Yes. Fortified plant milks use calcium carbonate from mineral sources, or sometimes tricalcium phosphate or calcium citrate, all mineral. Seaweed-derived calcium from Lithothamnion is also used and is algal.

Why is calcium carbonate added to flour?

UK regulations have required it in most flour since 1943 as a public health measure, alongside iron and B vitamins. Wholemeal flour is exempt from the requirement. Most other countries do not mandate it.

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