Sodium citrates
Sodium salts of citric acid, used to control acidity and help ingredients mix evenly in processed foods.
What is it?
Sodium citrates are the sodium salts of citric acid, a naturally occurring acid found in citrus fruit. The E331 group covers three forms: monosodium citrate (E331i), disodium citrate (E331ii), and trisodium citrate (E331iii), each carrying a different number of sodium ions. They are produced commercially by neutralising citric acid with sodium hydroxide or sodium carbonate.
What does it do?
Sodium citrates act as buffers, resisting changes in pH so a product stays at its intended acidity even after heating, mixing, or dilution. They also act as sequestrants, binding trace metal ions that would otherwise trigger rancidity or colour loss. In processed cheese, trisodium citrate acts as an emulsifying salt by displacing calcium from the protein network, allowing fat and water to stay combined in a smooth, melt-stable texture. In carbonated drinks they moderate the sharpness of citric acid.
Where you will see it
Most commonly found in processed cheese slices and spreads, carbonated soft drinks, flavoured waters, sports and energy drinks, instant soups, dessert mixes, jams, and some ready meals. On a UK label it appears as 'sodium citrates', 'trisodium citrate', or 'E331'.
What the science says
Sodium and dietary intake
Sodium citrates contribute a small amount of sodium to the diet, which is relevant for people managing their sodium intake. However, sodium citrate is used at relatively low levels in food, so its contribution to total daily sodium is typically minor compared to sodium chloride (table salt). Citrate itself is metabolised normally by the body as part of the citric acid cycle.
Sodium citrates are metabolised to bicarbonate in the body and do not accumulate; the sodium component counts toward total dietary sodium intake.
Kidney stone risk with high citrate intake
Citrate in urine inhibits the formation of calcium oxalate kidney stones, which is why pharmaceutical sodium citrate is sometimes used therapeutically. At food additive levels, the amounts consumed are far below therapeutic doses. No concern about stone formation from food-additive use has been identified by regulators.
Urinary citrate is an established inhibitor of calcium oxalate crystallisation; supplemental citrate is used clinically to reduce stone recurrence, but food-additive exposure has not been linked to adverse renal effects.
Where it stands with the regulators
Who should be careful
People on medically supervised low-sodium diets should be aware that sodium citrates add a small amount of sodium; they appear on the label as 'sodium citrates' or 'E331'. No other group needs to specifically avoid this additive.
The honest read
Sodium citrates are among the most thoroughly reviewed and longest-established food additives in use. They are chemically identical to the citrate naturally present in citrus fruit and vegetables, and the body processes them through normal metabolic pathways. Regulators in both the UK and EU have reviewed the group and found no basis for setting a numerical intake limit. There is no credible body of research linking food-additive levels of sodium citrates to harm. The only practical consideration is the sodium contribution for people on strict low-salt regimens.
Related additives
Common questions
Is E331 banned in the UK?
No. Sodium citrates (E331) are approved food additives in the UK under the assimilated EU Regulation 1333/2008, and that status has been maintained since Brexit. They have never been banned or restricted.
Does E331 contain a lot of sodium?
Sodium citrates do contain sodium, but they are typically used at low levels in food. The sodium contribution from E331 is small compared with sodium chloride (table salt), the main source of dietary sodium. People on medically supervised low-sodium diets should check total sodium figures on the nutrition panel rather than singling out E331.
What foods contain E331?
Sodium citrates appear most often in processed cheese slices and spreads, carbonated soft drinks, sports and energy drinks, instant soups, jams, and some ready meals. Look for 'sodium citrates', 'trisodium citrate', or 'E331' in the ingredients list.
Is E331 vegan?
Yes. Sodium citrates are produced from citric acid (typically fermented from plant sugars) neutralised with sodium compounds. No animal-derived ingredients are involved, and E331 is considered suitable for vegans and vegetarians.
Sources
- EFSA ANS Panel opinion on citric acid and its ammonium, calcium, potassium and sodium salts (E 330-333)
- UK FSA Approved Additives and E Numbers
- EU Regulation 1333/2008 on food additives (Annex II)
- Pak CY et al., Urinary citrate as an inhibitor of crystallisation of calcium salts, Kidney International
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