E-numbers / Acidity regulators / E331

Sodium citrates

also: Monosodium citrate · Disodium citrate · Trisodium citrate · Sodium salt of citric acid

Salts of citric acid that keep acidity steady and help processed cheese melt smoothly. A large French study linked eating more of them to type 2 diabetes.

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An ingredient list from the soft drinks and juices aisle

Carbonated Water, Citric Acid, Flavourings, Acidity Regulator (Sodium Citrates), Sweeteners (Acesulfame K, Sucralose), Preservative (Potassium Sorbate)

E331Acidity regulator

Sodium citrates

Sodium citrates are salts of citric acid, the acid in citrus fruit.

VeganVegetarian

2,360

of the 43,325 UK supermarket foods we checked declare E331 in their ingredients

That is 5.4%, counted by its code or its name.

Only 11% of these labels print “E331”. Most use the name: look for “sodium citrates”.

Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted

How common it is in UK food, by aisle

Soft drinks and juices778 products30% of 2,627
Cakes, biscuits and desserts426 products11% of 3,715
Bread and bakery230 products6.2% of 3,682
Yoghurt, milk and dairy142 products6.2% of 2,273

What sodium citrates is, what it does and where you will see it

What is it?

Sodium citrates are salts of citric acid, the acid in citrus fruit. There are three forms, E331i, E331ii and E331iii, carrying different amounts of sodium. They are made by mixing citric acid with a sodium compound.

What does it do?

They keep a food at a steady level of acidity, even after heating, mixing or diluting. They lock up traces of metal that would otherwise make food go rancid or lose colour. In processed cheese, trisodium citrate pulls calcium out of the milk protein so fat and water stay mixed, which is what makes a cheese slice melt smoothly. In fizzy drinks they soften the sharpness of citric acid.

Where you will see it

Processed cheese slices and spreads, fizzy drinks, flavoured waters, sports and energy drinks, instant soups, dessert mixes, jams and some ready meals. UK labels call them sodium citrates, trisodium citrate or E331.

What the science says

Linked to type 2 diabetes in a large French study

The NutriNet-Santé study asked more than 100,000 French adults to record everything they ate, then followed their health for about 7 years. People who ate more sodium citrate were more likely to develop type 2 diabetes. It was one of several additives linked in the study. This shows a link, not proof that sodium citrate causes diabetes, and the researchers called for more research.

Among 104,139 French adults followed for an average of 6.8 years, each extra 500mg of sodium citrate eaten a day was linked to a 4% higher risk of type 2 diabetes.

2024Observational study in peopleSalame et al., The Lancet Diabetes & Endocrinology, NutriNet-Santé cohort

They add a little sodium

Sodium citrates add a little sodium to the diet, which matters for people cutting down. They are used in small amounts, so they usually add much less sodium than table salt. The body turns citrate into bicarbonate through its normal energy cycle.

Sodium citrates are turned into bicarbonate in the body and do not build up. Their sodium counts towards total sodium intake.

2014Regulator reviewEFSA Panel on Food Additives and Nutrient Sources Added to Food (ANS Panel)

Citrate helps prevent some kidney stones

Citrate in urine stops calcium oxalate kidney stones forming, which is why doctors sometimes prescribe sodium citrate. The amounts in food are far below those doses. Regulators have not found any problem with kidney stones from its use in food.

Citrate in urine is a known blocker of calcium oxalate crystals, and supplemental citrate is used in clinics to reduce stones coming back. Citrate from food additives has not been linked to kidney harm.

1985ObservationalKidney International, Pak et al.

Where it stands with the regulators

Approved in the UK and the EU

Daily limit. None set.

Legal basis: On the Food Standards Agency's approved list for Great Britain. Also allowed as a processing aid and carrier.
Permitted foods: Processed cheese · Fizzy drinks and flavoured waters · Sports and energy drinks · Jams, jellies and marmalades · Instant soups and sauces · Dessert mixes · Ready meals · Infant formula (trisodium citrate, at set levels)
Maximum levels: No set maximum in most foods, as long as makers use no more than they need. Infant formula has set limits.
History: Sodium citrates have been allowed in UK and EU food for several decades. European reviewers looked at citric acid and its salts together in 2014 and set no numerical daily limit. The UK kept the approval after Brexit. No restrictions, bans or warnings have ever applied to E331. In 2024 a large French study linked higher intake to type 2 diabetes, which regulators have not yet assessed.

Who should be careful

People on a low-sodium diet set by their doctor should know sodium citrates add a little sodium. Look for sodium citrates or E331 on the label.

The honest read

Sodium citrates are among the longest-used additives in food. They are chemically the same as the citrate in citrus fruit and vegetables, and the body processes them through its normal energy cycle. UK and EU regulators have found no basis for a numerical daily limit.

The new question is the French NutriNet-Santé research, which linked higher intakes to type 2 diabetes. That is one large study of adults and shows a link rather than proof, so it needs repeating before anyone can call it settled. Being the same as the citrate in a lemon is also why an E-number on its own says little about how processed a food is. For that question, see our ultra-processed foods list.

Common questions about sodium citrates

Is E331 banned in the UK?

No. Sodium citrates are approved in the UK and have kept that approval since Brexit. They have never been banned or restricted.

Is E331 linked to diabetes?

A French study of 104,139 adults, published in 2024, found that people who ate more sodium citrate were more likely to develop type 2 diabetes: each extra 500mg a day was linked to a 4% higher risk. It is one observational study and shows a link, not proof of cause.

Does E331 contain a lot of sodium?

They do contain sodium, but they are used in small amounts, so they add much less than table salt. People on a low-sodium diet set by their doctor should look at the total salt figure on the nutrition panel rather than singling out E331.

What foods contain E331?

Mostly processed cheese slices and spreads, fizzy drinks, sports and energy drinks, instant soups, jams and some ready meals. Look for sodium citrates, trisodium citrate or E331.