What is it?
Calcium carbonate is the mineral in chalk, limestone and marble. The food version is either ground from limestone or made by a chemical process that forms it as a powder. It is white, has no smell and barely dissolves in water.
E-numbers / Other additives / E170
Calcium carbonate
also: Chalk · E170(i) · Calcium carbonates
Chalk. UK law makes millers add it to white flour, so it is in most bread. The chalk itself is not the issue, the aluminium that comes with it is.
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Water Oat (11.9%) Sunflower oil Calcium (Calcium carbonate) Chicory root fibre Sea salt Stabiliser (Gellan gum) Potassium iodide Vitamins B2 B9 D2.
E170
Calcium carbonate
The chalk used in food can carry aluminium that cannot be removed.
VeganVegetarian
6,148
of the 43,325 UK supermarket foods we checked declare E170 in their ingredients
That is 14%, counted by its code or its name. The count includes every form of E170 (E170b).
In 5,552 of these (90%), the only calcium carbonate is in the wheat flour, where UK law requires it to be added.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
How common it is in UK food, by aisle
- Bread and bakery1,917 products52% of 3,682
- Ready meals and pizza1,150 products24% of 4,833
- Cakes, biscuits and desserts1,088 products29% of 3,715
- Fresh meat, poultry and fish762 products16% of 4,835
What calcium carbonate is, what it does and where you will see it
Why it’s worth knowing. The chalk used in food can carry aluminium that cannot be removed. In 2023 European reviewers found the aluminium from E170 could push some groups past the weekly aluminium limit when it is used in many foods, and called for stricter aluminium limits.
What does it do?
It makes coatings bright white. It cancels out acid, so a food stays at a steady level of acidity without tasting different. It soaks up moisture so powders pour freely. And it adds calcium, including where the law requires it.
Where you will see it
By law, all non-wholemeal wheat flour milled in the UK has chalk added, so it is in most everyday bread, cakes and biscuits. It is also in breakfast cereals, plant milks (oat, soya, almond), tofu, chewing gum, sugar-coated sweets, cake decorations, supplements and the rind of some ripened cheese. Labels call it calcium carbonate or E170.
What the science says
Aluminium comes with the chalk
Limestone naturally holds traces of aluminium that cannot be fully removed. In 2023 European reviewers found the aluminium carried in E170 could make up 50 to 100% of the weekly aluminium limit in some groups. At the aluminium levels makers had proposed as a maximum, some groups could go about four times over it. Reviewers called for new, lower aluminium limits in the rules for E170.
Aluminium from E170 could make up 50 to 100% of the weekly limit of 1mg of aluminium per kg of body weight, and could go well over it in some groups at the highest levels measured.
2023Regulator reviewEFSA Panel on Food Additives and Flavourings (FAF), EFSA Journal 2023, volume 21, 8106
The unavoidable aluminium in E170 is a concern and should be dealt with through stricter purity rules.
2023Regulator reviewEFSA Panel on Food Additives and Flavourings (FAF), EFSA Journal 2023, volume 21, 8106
The calcium carbonate itself
European reviewers looked at calcium carbonate in 2011 and again in 2023, including in foods for babies under 16 weeks, and set no numerical daily limit, because at food amounts it behaves like the calcium already in the diet. The calcium it adds is a small part of the calcium people eat overall.
Reviewers saw no need for a numerical daily limit for calcium carbonate as an additive and agreed with the existing "not specified" position.
2011Regulator reviewEFSA ANS Panel, EFSA Journal 2011, volume 9, 2318
The calcium from calcium carbonate as an additive is only a small part of total calcium intake, and reviewers did not see it as a concern.
2023Regulator reviewEFSA Panel on Food Additives and Flavourings (FAF), EFSA Journal 2023, volume 21, 8106
Why UK flour has chalk in it
Since 1942, UK law has required chalk to be added to non-wholemeal wheat flour, to protect people's calcium intake when wartime diets changed. The Bread and Flour Regulations still require it. The chalk must meet set purity rules, and the Real Bread Campaign reported in 2024 that the supply of chalk meeting them comes from a single quarry in France.
The Bread and Flour Regulations require calcium carbonate to be added to non-wholemeal wheat flour, a requirement in place since 1942.
2024LawUK Bread and Flour Regulations 1998 (as amended 2024), DEFRA
Where it stands with the regulators
Approved in the UK and the EU, and required by law in non-wholemeal flour in the UK
Daily limit. None set.
- Legal basis
- On the Food Standards Agency's approved list for Great Britain, with purity rules in assimilated Regulation 231/2012. Required in non-wholemeal flour by the UK Bread and Flour Regulations 1998 (as amended).
- Permitted foods
- Non-wholemeal wheat flour (required) · Bread and baked goods · Sweets and sugar coatings · Chewing gum · Ripened cheese · Breakfast cereals · Supplements · Plant milks · Processed fruit and vegetables · Many other foods with no set maximum
- Maximum levels
- No set maximum in most foods, as long as makers use no more than they need. Some foods have set limits.
- History
- The international committee set no numerical daily limit. European reviewers kept that position in 2011. In 2023 they looked again, covering foods for babies under 16 weeks and following up the aluminium impurity flagged in 2011. They called for new maximum aluminium limits in E170 and lower limits in E170 used in baby food. The UK flour requirement dates from 1942, before modern additive law.
Who should be careful
People with high blood calcium or a history of calcium kidney stones should keep an eye on total calcium from all sources, including fortified foods. This mostly matters for high-dose supplements rather than E170 in food. Labels call it calcium carbonate or E170.
The honest read
The additive is chalk, a mineral people have eaten in food and water for as long as they have eaten. European reviewers have looked at it twice and set no limit on the calcium carbonate itself. The open question from 2023 is what comes with it: aluminium occurs naturally in limestone and cannot be fully removed. Reviewers called for tighter limits, and whether those are yet written into law is still being worked through. How much aluminium any one person gets from E170 depends on how many foods with it they eat, and in the UK that includes most bread.
Common questions about calcium carbonate
Is E170 banned in the UK?
No. Calcium carbonate is approved in the UK, and the law requires it to be added to most non-wholemeal wheat flour.
Why did European reviewers flag E170 in 2023?
Not because of the calcium carbonate, but because of the aluminium that occurs naturally in the limestone it is made from. They found that in some groups, aluminium from E170 could push weekly intake past the limit, and called for stricter aluminium limits in its purity rules.
What foods contain E170?
Most everyday bread and baked goods in the UK, because it is required in non-wholemeal wheat flour. Also many breakfast cereals, plant milks, chewing gum, sugar-coated sweets and supplements. Labels call it calcium carbonate or E170.
Is E170 vegan?
Usually, but not always. Most food-grade calcium carbonate comes from quarried limestone. It can also be made from oyster shells, eggshells and other animal shells. Makers do not have to say which, so the label alone cannot confirm it.
Sources
- EFSA FAF Panel: Re-evaluation of calcium carbonate (E 170) as a food additive in foods for infants below 16 weeks of age and follow-up of its re-evaluation as food additive for uses in foods for all population groups. EFSA Journal 2023;21(7):8106
- PubMed: EFSA 2023 re-evaluation of E170
- PMC full text: EFSA 2023 re-evaluation of E170
- UK Food Standards Agency: Approved additives and E numbers
- UK FSA regulated products database: E-170
- Real Bread Campaign: Flour fortification chalk supply risk to the UK food system (December 2024)
- EFSA ANS Panel: Scientific Opinion on re-evaluation of calcium carbonate (E 170) as a food additive. EFSA Journal 2011;9(7):2318
- UK Bread and Flour Regulations 1998 (as amended), DEFRA
Last reviewed: 20 June 2026
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