What is it?
Sodium sulphite is a white to yellowish powder that releases sulphur dioxide when it meets acid or heat. It is one of the sulphite additives, E220 to E228, which are assessed together as a group.
E-numbers / Preservatives / E221
Sodium sulphite
also: Sodium sulfite · E221 · disodium sulphite
A sulphite that stops dried fruit, wine and prawns browning or spoiling. Labels must declare it as an allergen, because it can set off asthma.
Scan a barcode to check a food for sodium sulphite. NutraSafe Pro · £6.99/month · iOS
British beef (95%), rehydrated potato, rice flour, sea salt, salt, black pepper, preservative (sodium sulphite), dextrose, antioxidant (sodium ascorbate)
E221
Sodium sulphite
It can set off asthma attacks and breathing problems in people sensitive to sulphites, estimated at 5 to 13% of people with asthma.
VeganVegetarian
112
of the 43,325 UK supermarket foods we checked declare E221 in their ingredients
That is 0.3%, counted by its code or its name.
Only 1.8% of these labels print “E221”. Most use the name: look for “sodium sulphite”.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
How common it is in UK food, by aisle
- Fresh meat, poultry and fish81 products1.7% of 4,835
- Cooked and cured meats23 products1.2% of 1,938
What sodium sulphite is, what it does and where you will see it
Why it’s worth knowing. It can set off asthma attacks and breathing problems in people sensitive to sulphites, estimated at 5 to 13% of people with asthma. European reviewers withdrew the daily limit in 2022 after finding signs of nervous system effects in animals and receiving none of the new safety data they asked for. People with high intake in most age groups, children included, may go over the level reviewers consider acceptable.
What does it do?
It releases sulphur dioxide, which blocks the enzymes that turn food brown and kills bacteria, yeasts and moulds that spoil it. It also stops oxygen dulling colour and flavour. In some baking it softens gluten. It is not allowed in most meat, because it can hide the colour and smell changes that show meat is going off.
Where you will see it
Dried fruit such as apricots, raisins and sultanas, wine and beer, fruit juices and cordials, prawns and shellfish (to stop black spots), potato products including instant mash, vinegar and pickles, and starch and gelatine. Labels may say sodium sulphite, E221, sulphur dioxide or sulphites. UK law requires "contains sulphites" or "contains sulphur dioxide" above 10mg per kg or per litre in the food as eaten.
What the science says
Sulphites linked to more cancer in a large French study
In 2026 the NutriNet-Santé study reported that French adults who ate more sulphites, the group that includes sodium sulphite, had 12% more cancer overall. These are observational studies: they show links, not proof that the additive causes the disease.
Among 105,260 French adults followed for an average of 7.5 years, higher intake of sulphites as a group was linked to a 12% higher risk of cancer overall.
2026Observational study in peopleHasenböhler et al., The BMJ, NutriNet-Santé cohort
Asthma and breathing reactions
Sulphites release sulphur dioxide gas when they meet stomach acid, and the gas can irritate and narrow the airways. An estimated 5 to 13% of people with asthma are sensitive to sulphites, most often those with severe or steroid-treated asthma. Reactions can include wheezing, a tight chest and shortness of breath within minutes of eating. Anaphylaxis has been reported rarely.
Between 5 and 13% of people with asthma react to sulphites, with higher rates in those on steroids for asthma.
2023ObservationalAllergy UK, Sulphites and Airway Symptoms factsheet
Sulphites release sulphur dioxide on contact with stomach acid. The gas reaches the airways and makes them tighten through a nerve reflex and, in some people, an immune reaction.
Lab studyCharacterisation of bronchoconstrictor responses to sodium metabisulphite aerosol in atopic subjects, PMC1020876
Sulphites are one of the 14 major allergens under UK food law, and must be declared above 10mg per kg or per litre.
LawUK Food Standards Agency, food allergen labelling guidance
Reviewers withdrew the daily limit after nervous system signals
In 2016 European reviewers set a temporary shared daily limit of 0.7mg per kg of body weight for all sulphites, and found high consumers in several age groups already over it. By 2022, no new toxicity studies had been supplied, and they withdrew even the temporary limit. Using a margin-of-exposure approach instead, they found the safety margin below their threshold for most age groups, children and adults included, based on slowed nerve signals in animal studies.
Reviewers set a temporary shared daily limit of 0.7mg per kg of body weight for E220 to E228 in 2016, and found intake estimates over it for every group studied.
2016Regulator reviewEFSA Scientific Opinion on re-evaluation of sulfur dioxide and sulphites (E220-E228), EFSA Journal 2016, volume 14, 4438
In 2022 reviewers withdrew the temporary limit because the toxicity data were still inadequate and no new data had been submitted to fill the gaps.
2022Regulator reviewEFSA Follow-up re-evaluation of sulfur dioxide and sulphites (E220-E228), EFSA Journal 2022, volume 20, 7594
Using a reference point of 38mg per kg of body weight a day, from a slowed eye-to-brain nerve signal in animals, margins of exposure were below 80 for most age groups at high intake, except teenagers.
2022Regulator reviewEFSA Journal 2022, volume 20, 7594
In 2025 the European Commission asked reviewers to estimate intake under lower maximum levels, as a way to bring exposure down.
2025Regulator reviewEFSA Supporting Publications 2025, EN-9754: Update of dietary exposure to sulfur dioxide and sulphites with alternative maximum levels
It harmed helpful gut bacteria in the lab
A lab study found that sodium sulphite and sodium bisulphite slowed or killed four kinds of helpful gut bacteria at strengths found in sulphite-preserved food. It does not prove the same happens in the human gut at normal intakes, but the researchers noted that current limits were set without considering the potential effects on gut bacteria.
Sodium sulphite slowed or killed four Lactobacillus and Streptococcus species at 250 to 500ppm in the lab, levels the authors noted are within the range regulators allow.
2017Lab studyIrwin & Fisher, Sulfites inhibit the growth of four species of beneficial gut bacteria at concentrations regarded as safe for food, PLOS ONE 2017, volume 12, e0186629
It destroys vitamin B1
Sulphite splits the thiamine molecule, lowering the vitamin B1 in treated food. That is one reason UK and EU rules keep sulphites out of foods that are important sources of thiamine.
Sulphite splits the thiamine molecule in several steps, leaving the vitamin inactive, and does so faster in acidic conditions.
1984Lab studyDwivedi & Arnold, A mechanism for sulphite ion reacting with vitamin B1 and its analogues, Food Chemistry
Where it stands with the regulators
Approved in the UK and the EU
Daily limit. None currently set. The temporary shared limit of 0.7mg per kg of body weight for E220 to E228 was withdrawn in 2022, and risk is now judged by margin of exposure.
- Legal basis
- On the Food Standards Agency's approved list for England, Scotland and Wales
- Permitted foods
- Dried fruit and vegetables (such as apricots, raisins, sultanas) · Wine and beer · Fruit juices, cordials and syrups · Shellfish and prawns · Potato products, including instant mash · Vinegar and pickles · Starch and gelatine · Some bread and baking · Egg yolk products · Breakfast sausages and burger meat with at least 4% vegetable or cereal
- Maximum levels
- Set for each type of food, up to 2,000mg per kg in some dried fruit. Not allowed in most meat.
- History
- European reviewers looked at the sulphite group in 2016, set a temporary limit and noted high consumers in every age group were over it. Makers were asked for new toxicity data. In 2022 reviewers found none had been supplied, withdrew the temporary limit and said the data were inadequate to set a new one. They identified slowed nerve signals in animal studies and found safety margins too small for most age groups. In 2025 the European Commission asked for estimates under lower maximum levels. Sulphites have been a declarable allergen in EU and UK law since Directive 2003/89/EC, at 10mg per kg or per litre.
Who should be careful
People with asthma should know sulphites can set off attacks, particularly with severe or steroid-treated asthma. Anyone who has had breathing problems, hives or stomach reactions after wine, dried fruit or prawns should ask for an allergy assessment. On UK labels, look for sulphites, sulphur dioxide, E221 or "contains sulphites". Declaration is required above 10mg per kg or per litre, so some foods may contain smaller amounts without saying so. Our allergen checker flags sulphites where they appear in the ingredient list we hold for a pack. Read the label too, because our data can lag a recipe change.
The honest read
Sulphites are among the most contested preservatives in EU food law. The 2016 European review already found high consumers over the limit, and the 2022 follow-up withdrew even the temporary limit when the studies requested did not arrive, leaving regulators without a firm number. The nervous system signals come from animal studies and have not been confirmed in people at normal intakes. The asthma link is better established and written into UK allergen law. The gut bacteria finding comes from the lab and may not translate to the human gut. The science is not settled, and the basis for current permitted levels is under active review. In 2026 a large French study also linked sulphites as a group to 12% more cancer. It is observational, so it shows a link rather than proof.
Common questions about sodium sulphite
Is E221 banned in the UK?
No. E221 is approved in the UK and EU. It is not allowed in most meat, where it could hide signs of spoilage, though sausages and burger meat with added vegetable or cereal are an exception. Its safety assessment is under active review.
Why was the daily limit for sulphites withdrawn?
In 2022 European reviewers concluded the toxicity data were not enough to set a reliable limit. After the 2016 review, makers were asked to fund new studies to fill specific gaps, and no new data came. Reviewers withdrew the temporary 2016 limit and switched to a margin-of-exposure approach, which found safety margins too small for most age groups.
What foods contain E221?
Dried apricots and other dried fruit are among the highest in sulphites. It is also used in wine, beer, fruit juices, prawns and shellfish, instant mash, vinegar, pickles and some gelatine products. Labels may say E221, sodium sulphite, sulphur dioxide or "contains sulphites".
Is E221 vegan?
Yes. It is a mineral salt, with nothing from animals.
Sources
- UK FSA: Sodium sulphite (E221) regulatory authorisation record
- UK FSA: Approved additives and E numbers
- EFSA: Scientific Opinion on re-evaluation of sulfur dioxide (E220) and sulphites (E221-E228), EFSA Journal 2016;14(4):4438
- EFSA: Follow-up re-evaluation of sulfur dioxide and sulphites (E220-E228), EFSA Journal 2022;20(11):7594
- EFSA: PMC full text of 2022 sulfites follow-up (PMC9685353)
- EFSA Supporting Publications 2025 EN-9754: Update of dietary exposure to sulfur dioxide and sulphites with alternative maximum levels
- Allergy UK: Sulphites and Airway Symptoms factsheet
- Anaphylaxis UK: Sulphite Allergy fact sheet
- UK FSA: Food allergen labelling and information requirements technical guidance
- Irwin & Fisher, Sulfites inhibit the growth of four species of beneficial gut bacteria at concentrations regarded as safe for food, PLOS ONE 2017
- Dwivedi & Arnold, A mechanism for sulphite ion reacting with vitamin B1 and its analogues, Food Chemistry 1984
- PMC article: Characterisation of bronchoconstrictor responses to sodium metabisulphite aerosol in atopic subjects (PMC1020876)
- Hasenböhler A et al. (2026) Intake of food additive preservatives and incidence of cancer: results from the NutriNet-Santé prospective cohort, The BMJ
Last reviewed: 20 June 2026
It's the only app that does thisUKJaneK
You Need This AppGmac2005
Best AppGK getting skinny UK App Store reviews
See this on every food you scan
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
NutraSafe Pro · £6.99/month · iOS