Calcium citrates
The calcium salt of citric acid, used to control acidity, firm textures, and stabilise food products. Found widely in processed foods.
What is it?
Calcium citrates are the calcium salts of citric acid, a naturally occurring organic acid found in citrus fruit and produced commercially by fermentation. The E333 group covers three forms: monocalcium citrate (E333i), dicalcium citrate (E333ii), and tricalcium citrate (E333iii), differing in the ratio of calcium to citrate. All three are white, odourless powders.
What does it do?
Calcium citrates act as acidity regulators, stabilisers, firming agents, and sequestrants. As an acidity regulator they buffer the pH of food, keeping it stable during processing and storage. As a firming agent calcium ions cross-link with pectin in plant cell walls to keep vegetables and canned fruit from going soft. As a sequestrant they bind free metal ions that would otherwise catalyse rancidity or colour change. Tricalcium citrate is also used as a calcium supplement carrier in fortified foods because the citrate form improves mineral absorption.
Where you will see it
Commonly found in canned and jarred vegetables, jams and preserves, processed cheese, infant formula and follow-on formula, sports and meal-replacement drinks, calcium-fortified plant milks, low-calorie soft drinks, baked goods, and dry powder mixes. On the label it appears as calcium citrate, dicalcium citrate, tricalcium citrate, or simply E333.
What the science says
Toxicological assessment and ADI
Citric acid and its calcium, sodium, and potassium salts have been in the human diet for centuries through fruit consumption and have been reviewed repeatedly by food safety bodies. EFSA's Panel on Food Additives and Nutrient Sources (ANS) concluded that no numerical acceptable daily intake was necessary for calcium citrates because the intake from food use does not represent a toxicological concern. This is the strongest category of clearance a regulator can give: the substance is so well characterised and so close to normal dietary components that setting a number adds nothing.
EFSA ANS Panel concluded that citric acid and its ammonium, calcium, potassium, and sodium salts do not raise a safety concern at the reported uses and use levels, and a numerical ADI was not considered necessary.
Calcium contribution from citrate-form supplements and fortified foods
Tricalcium citrate in fortified foods contributes bioavailable calcium to the diet. Research comparing calcium absorption from different salts generally finds citrate forms absorbed well, including without food. However, from an additive-use perspective the quantities present in acidity-regulated or firmed foods are small relative to total dietary calcium intake, so the contribution to overall calcium status is modest. This is a nutritional consideration rather than a concern.
Calcium from calcium citrate supplements showed comparable or somewhat higher absorption relative to calcium carbonate in controlled studies, particularly when taken without food.
Where it stands with the regulators
Who should be careful
People with hypercalcaemia (abnormally high blood calcium) or conditions requiring strict calcium restriction should note that fortified foods carrying E333 as a calcium source add to total calcium intake. The label term to check is calcium citrate or E333 in the ingredients list, alongside any 'with added calcium' claim on the front of pack.
The honest read
Calcium citrates sit at the very ordinary end of the food-additive spectrum. Citric acid itself is a core metabolite in every human cell, and its calcium salt is close to compounds the body handles continuously. There is no live scientific controversy, no restriction, and no watchlist placement for this additive. The science on it is not unsettled; it is simply well-established and unremarkable.
Related additives
Common questions
Is E333 banned in the UK?
No. Calcium citrates are fully authorised in the UK under the assimilated EU Regulation 1333/2008 (Annex II), retained in Great Britain law post-Brexit. The UK FSA lists all three sub-forms (E333i, E333ii, E333iii) as permitted.
Does E333 count as a calcium supplement?
Tricalcium citrate (E333iii) is widely used as the calcium carrier in fortified plant milks, infant formulas, and meal-replacement drinks, so it does contribute bioavailable calcium. In other roles, such as a firming agent in canned vegetables, the quantity present is small and the calcium contribution to the diet is minor.
What foods contain E333?
Calcium citrates are found in canned and jarred vegetables, jams and preserves, processed cheeses, infant formula, calcium-fortified plant milks and juices, sports drinks, and dry bakery mixes. Look for 'calcium citrate', 'tricalcium citrate', or 'E333' in the ingredients list.
Is E333 vegan?
Yes. All three forms of calcium citrate are produced by chemical synthesis from citric acid (itself fermentation-derived) and calcium carbonate, with no animal-derived inputs. E333 is suitable for vegan and vegetarian diets.
Sources
- UK FSA Approved Additives and E Numbers - E333 Calcium Citrates
- UK Food Standards Agency - Approved Additives and E Numbers
- EFSA ANS Panel - Re-evaluation of citric acid (E 330) and its ammonium, calcium, potassium and sodium salts, EFSA Journal
- EU Regulation 1333/2008 on food additives (Annex II) - assimilated in UK law
- Harvey et al. - Calcium citrate: Reduced propensity for the crystallization of calcium oxalate in urine resulting from induced hypercalciuria of calcium supplementation, Journal of the American College of Nutrition
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