Calcium Carbonate:

Calcium carbonate is a chemical compound that has many industrial applications. It is used medicinally, and as a food additive.


Calcium carbonate is the main component in egg shells. It is also a main component in the shells of marine animals and snails.1 However, most of the calcium carbonate used industrially comes from mining. Even when used in pharmaceuticals or as a food additive, it is often produced from quarried marble.2

The chemical formula of calcium carbonate is CaCO3. It typically comes as a white solid, either crystals or powder. It is odorless, chalky, and flat. It can have a sweetish flavour.

Calcium carbonate is not soluble in water. However, it can be emulsified to disperse in water.

The E number of calcium carbonate is 170. This means that it is classified as a food colour, even thought it has many other uses.

Common Uses:

When used in food, it can:

  • Control acidity,
  • Act as a white food colour,
  • Act as a firming agent for vegetables,
  • Act as a nutrient for yeasts,
  • Add an additional source of calcium,

Calcium carbonate is a stable food coloring. It does not require any special processing to preserve its coloring properties.2 It can also be used as a food preservative and color retainer in organic fruits and other foods.

Many foods (especially soy milk and soy products) are calcium enriched. Calcium carbonate is often used as the calcium source.

It can also be a stabilizer, added mainly to dairy products.

There are a lot of uses of calcium carbonate. It can be found in almost all kinds of foods from dried fruits to canned sardines, also in frozen foods, cereals, aromatized beverages and processed meat and fish products.3

In some beer brewing operations, calcium carbonate is used as a nutrient for the yeast.

Health Issues / Side Effects:

Calcium carbonate can be potentially harmful only in concentrated solid form or in very concentrated solutions.

Otherwise, direct eye or skin contact with pure crystals or powder can produce irritation. Breathing crystals or powder can be irritating to the respiratory tract, and contact with concentrated solutions of calcium carbonate has a drying effect on skin.4


In 1861, a Belgian chemist named Ernest Solvay, invented a process for producing sodium carbonate (sometimes called soda ash). Sodium carbonate was coming into high demand at the time because it is used in glass making. Glass is made by melting silica sand, calcium carbonate and sodium carbonate together.

Solvay’s process basically takes limestone (CaCO3) and salt Brine (2 NaCl) to produce sodium carbonate (Na2CO3). The main by-product of the Solvay process is calcium chloride.


  1. Wikipedia
  2. DDW Color – Food Colouring Manufacturer
  3. Calcium Carbonate In-R-Food
  4. Oregon Department of Human Services

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3 Comments on “Calcium Carbonate

    • Thanks for the comment Mary.
      It really amazes me when I think about all the time, money, and effort that must be spent developing all of these food colourings. In so many cases, we really don’t have a good understanding of how they affect our bodies.

  1. I’ve been looking for this comprehensive information for a while now. Thank you for making it available. I wish fast food outlets would also add to their takeaway box what E- numbers for their taste enhancers and colorants they have used.

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