What is it?
Sodium benzoate is a man-made preservative, a salt of benzoic acid. It is one of the most widely used food preservatives, and works best in sour, acidic products such as fizzy drinks, fruit juices and pickles.
E-numbers / Preservatives / E211
Sodium benzoate
also: benzoate of soda
A synthetic preservative that stops bacteria, yeast and mould growing in acidic foods and drinks. In drinks that also contain vitamin C it can form small amounts of benzene.
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Scottish Spring Water, Acid (Citric Acid), Flavourings, Preservatives (Dimethyl Dicarbonate, Sodium Benzoate), Sweeteners (Acesulfame K, Sucralose)
E211
Sodium benzoate
In soft drinks it can react with added vitamin C to form benzene, which causes cancer, especially when the drink gets warm or sits in the light.
VeganVegetarian
UK supermarket foods that declare E211: 384 of the 43,325 we checked (0.9%)
Counted by its code or its name in the ingredient list.
Only 19% of these labels print “E211”. Most use the name: look for “sodium benzoate”.
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 juices166 products6.3% of 2,627
- Fruit, vegetables and salad54 products2.1% of 2,631
- Sauces, dressings and condiments32 products1.1% of 2,776
- Alcoholic drinks22 products1.2% of 1,857
What sodium benzoate is, what it does and where you will see it
Why it’s worth knowing. In soft drinks it can react with added vitamin C to form benzene, which causes cancer, especially when the drink gets warm or sits in the light. It can also set off reactions in some people with asthma, aspirin sensitivity or long-term hives.
What does it do?
It stops bacteria, yeast and mould growing, but only in acidic food. The acid lets it get inside the microbe's cells, where it lowers the acidity and cuts off the energy the microbe needs to grow.
Where you will see it
Acidic soft drinks and energy drinks, fruit juices and squashes, pickles, sauces, salad dressings, jams and some sweets. Labels call it sodium benzoate or E211, usually listed as a preservative.
What the science says
Can form benzene, which causes cancer, in drinks with vitamin C
When a drink contains both sodium benzoate and vitamin C (ascorbic acid), the two can react to form benzene, which causes cancer in people. Heat and light speed this up. Regulators tested drinks in the 2000s. A few went over the limit for drinking water.
Benzene can form at low levels in drinks that contain both benzoate and vitamin C. Heat and light encourage it.
Regulator guidanceUS FDA, Questions and Answers on Benzene in Soft Drinks
The FDA tested almost 200 drinks between 2005 and 2007. 10 held more than 5 parts per billion of benzene, the drinking-water limit.
2007Regulator surveyUS FDA benzene survey
Benzene is classed as a cause of cancer in people (Group 1).
Cancer classificationWHO/IARC
Part of the mixture linked to hyperactivity in the Southampton study
In the 2007 Southampton study, children drank mixes of artificial colours with sodium benzoate and became more hyperactive. Because benzoate was always given with the colours, the study could not tell how much of the effect, if any, came from benzoate itself. The warning label that followed applies to the six colours, not to E211.
Mixtures of four artificial colours plus sodium benzoate increased hyperactivity in 3-year-olds and 8 to 9-year-olds from the general population.
2007Randomised trial in peopleMcCann et al., The Lancet
European reviewers said the study gave limited evidence of a small effect. The effects were not consistent across the two age groups or two mixtures, and benzoate's own part could not be separated out.
2008Regulator reviewEFSA AFC Panel opinion on McCann et al.
Can worsen asthma and set off hives in sensitive people
A small number of people react to benzoates. Reported reactions include asthma getting worse, and bouts of hives and swelling, more often in people who are also sensitive to aspirin.
Under controlled testing, sodium benzoate brought on repeated bouts of hives and swelling in sensitive people.
ObservationalControlled challenge study, sodium benzoate urticaria/angio-oedema
Benzoate can worsen asthma in some people with asthma, especially those sensitive to aspirin.
ObservationalPublished clinical reports on benzoate and asthma
Some children may go over the daily limit
European reviewers looked at the benzoates again in 2016 and kept the daily limit at 5mg per kg of body weight, measured as benzoic acid. They also warned that, at current use, some groups who take in more, such as children, could go over it.
Reviewers set the daily limit at 5mg per kg of body weight a day, as benzoic acid.
2016Regulator reviewEFSA ANS Panel re-evaluation of E210-E213
Where it stands with the regulators
Permitted as a preservative in the UK and EU
Daily limit. 5mg per kg of body weight a day, about 350mg for a 70kg adult, measured as benzoic acid (European reviewers, 2016).
- Legal basis
- On the Food Standards Agency's register of approved additives for England, Scotland and Wales
- Permitted foods
- Soft drinks and flavoured drinks · Fruit juices, concentrates and squashes · Pickles and vegetables in vinegar or brine · Sauces, dressings and condiments · Jams and fruit preparations · Some sweets
- Maximum levels
- Depends on the food, from about 150mg per kg up to around 2000mg per kg, measured as benzoic acid.
- History
- From the 1990s, first the soft-drink industry and then regulators found benzene could form in drinks containing benzoate and vitamin C. FDA surveys found a few products over the 5 parts per billion drinking-water limit, and those were changed, often by switching to potassium sorbate or dropping the added vitamin C. European reviewers in 2016 kept the 5mg per kg daily limit but noted some high-consuming groups may go over it.
Who should be careful
People with a diagnosed benzoate sensitivity, aspirin sensitivity, long-term hives, or asthma that flares after preserved drinks should look for sodium benzoate or E211 on the label and talk to their doctor about avoiding it. A record of which drinks came before a flare makes that conversation useful, and that is what our food reaction tracker builds.
The honest read
The benzene risk is real but specific. It needs benzoate and vitamin C together in a drink, plus heat or light. The hyperactivity link comes from a study where benzoate was always mixed with artificial colours, so its own part is unclear.
Common questions about sodium benzoate
Is E211 banned in the UK?
No. It is an approved preservative in the UK and EU and is on the Food Standards Agency's register of approved additives.
Does sodium benzoate form benzene in drinks?
It can, but only when the drink also contains vitamin C (ascorbic acid), and heat and light speed it up. FDA surveys in the 2000s found a few drinks over the 5 parts per billion drinking-water limit, and those products were changed or withdrawn.
Is E211 harmful?
It is approved with a daily limit of 5mg per kg of body weight, and reviewers warned some children may go over it. In drinks that also contain vitamin C it can form benzene, which causes cancer. It can worsen asthma or set off hives in a small number of sensitive people.
What foods contain E211?
Mainly acidic products: soft and energy drinks, fruit juices and squashes, pickles, sauces and dressings, jams and some sweets. Labels call it sodium benzoate or E211.
Is E211 vegan?
Yes. Sodium benzoate is made in a factory from benzoic acid and contains nothing from animals.
Sources
- FSA - Approved additives and E numbers
- EFSA (2016) - Re-evaluation of benzoic acid (E210), sodium benzoate (E211), potassium benzoate (E212), calcium benzoate (E213)
- US FDA - Questions and Answers on the Occurrence of Benzene in Soft Drinks and Other Beverages
- McCann et al. (2007), The Lancet - Food additives and hyperactive behaviour in children
- EFSA (2008) - Assessment of the results of the study by McCann et al. (2007)
Last reviewed: 9 November 2026
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