Sulphur dioxide

also: Sulfur dioxide · SO2

The gas that keeps dried apricots orange and wine from spoiling. It is one of the 14 allergens labels must declare, because it can set off asthma.

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An ingredient list from the alcoholic drinks aisle

Grapes, Acidity Regulator (Tartaric Acid), Preservatives (Sulphur Dioxide, Potassium Metabisulphite), Dried Egg White, Packaging Gas (Carbon Dioxide).

E220Preservative · Synthetic

Sulphur dioxide

It can cause wheezing, a tight chest and asthma attacks in people with asthma.

VeganVegetarian

UK supermarket foods that declare E220: 507 of the 43,325 we checked (1.2%)

Counted by its code or its name in the ingredient list.

Only 3.9% of these labels print “E220”. Most use the name: look for “sulphur dioxide”.

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

How common it is in UK food, by aisle

Alcoholic drinks165 products8.9% of 1,857
Crisps and savoury snacks102 products3% of 3,428
Fruit, vegetables and salad38 products1.4% of 2,631
Ready meals and pizza28 products0.6% of 4,833

What sulphur dioxide is, what it does and where you will see it

Why it’s worth knowing. It can cause wheezing, a tight chest and asthma attacks in people with asthma. In 2022 European reviewers flagged a possible concern at high intakes for most age groups and withdrew the daily limit, because the toxicity data were too incomplete to set a new one.

What is it?

Sulphur dioxide is a colourless gas made by burning sulphur. In food it is used as a gas, dissolved in water, or released by related sulphite salts (E221 to E228).

What does it do?

It works two ways. It mops up oxygen and blocks the enzymes that turn cut fruit and vegetables brown. And it stops yeasts, moulds and bacteria growing by damaging their cell walls and enzymes, which prevents fermentation and spoilage.

Where you will see it

Highest in pale dried fruit, especially dried apricots: the bright orange is a sign of sulphur dioxide, and untreated apricots go brown. Also wine, cider, grape juice, beer, pickles, sausages and burgers with added vegetable or cereal, dried and frozen potato products, and fresh or frozen prawns. UK labels call it sulphur dioxide, sulphites or E220 (and E221 to E228 for related salts). It must be highlighted in the ingredients above 10mg per kg or per litre.

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 sulphur dioxide, had 12% more cancer overall. These are observational studies.

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

Sulphur dioxide irritates the airways. When sulphites in food meet stomach acid they release the gas, which can reach the airways and make them tighten. Under 2% of people overall are affected, but 5 to 13% of people with asthma react, and people on steroids for asthma are most at risk. Reactions range from mild wheezing to serious difficulty breathing, usually within minutes to an hour.

Sulphites trigger asthma symptoms, such as wheezing, a tight chest and coughing, in an estimated 5 to 13% of people with asthma, against under 2% of people overall.

2023Clinical guidanceAllergy UK, Sulphites and Airway Symptoms factsheet

Reactions to sulphites include asthma, hives, swelling, stomach pain, nausea and diarrhoea, and rarely anaphylaxis.

ObservationalAnaphylaxis UK, Sulphite fact sheet

Sulphite sensitivity is more common in people with poorly controlled asthma and very reactive airways, and reactions usually do not respond to antihistamines.

Clinical guidanceAustralasian Society of Clinical Immunology and Allergy (ASCIA), Sulfite Sensitivity

Reviewers withdrew the daily limit in 2022

In 2016 European reviewers set a temporary daily limit of 0.7mg per kg of body weight, and even then estimated that intake in every age group was over it. They asked makers for more toxicity studies. None were supplied, and in 2022 reviewers concluded the data were too incomplete to set any limit, and withdrew it. Using a different method, a margin of exposure, they found the safety margin at high intakes fell below their threshold for most age groups, a possible concern.

In 2016 reviewers set a temporary shared daily limit of 0.7mg per kg of body weight, but noted intake estimates were already over it in every age group.

2016Regulator reviewEFSA Journal: Scientific Opinion on the re-evaluation of sulfur dioxide (E 220) and sulphites (E 221-228) as food additives

In 2022 reviewers withdrew the temporary limit because the toxicity data were not enough to set one. Their margin-of-exposure approach gave margins below the protective threshold of 80 at high intakes, raising a safety concern.

2022Regulator reviewEFSA Journal: Follow-up of the re-evaluation of sulfur dioxide (E 220) and sulphites (E 221-228), doi:10.2903/j.efsa.2022.7594

Effects on the nervous system in animal studies

The 2022 review picked out effects on the nervous system as the most important new concern. In rats, sulphite slowed the nerve signal from the eye to the brain and increased damage to fats in brain tissue. Reviewers based their reference point on this.

Sodium metabisulphite slowed the eye-to-brain nerve signal and increased fat damage in rat brain tissue, more so at higher doses.

2010Animal studyDose-dependent effect of nutritional sulfite intake on visual evoked potentials and lipid peroxidation, Toxicology Letters

Reviewers used the slowed eye-to-brain signal as the key effect for their 2022 assessment, with a reference point of 38mg per kg of body weight a day from the animal evidence.

2022Regulator reviewEFSA Journal: Follow-up of the re-evaluation of sulfur dioxide (E 220) and sulphites (E 221-228), doi:10.2903/j.efsa.2022.7594

It destroys vitamin B1

Sulphur dioxide breaks down thiamine, vitamin B1, in food, the more so at higher doses. That is why UK and EU law keep it out of foods that are an important source of thiamine.

Sulphur dioxide splits the thiamine molecule in food, leaving vitamin B1 the body cannot use.

1935Lab studyWilliams, Studies of Crystalline Vitamin B1, Journal of the American Chemical Society

Cats and dogs fed mostly on sulphite-preserved pet meat developed thiamine deficiency.

1986ObservationalRead & Harrington, Thiamine deficiency in cats and dogs associated with feeding meat preserved with sulphur dioxide, Australian Veterinary Journal

Where it stands with the regulators

Approved in the UK and the EU

Daily limit. None currently set. The temporary limit of 0.7mg per kg of body weight was withdrawn in 2022 because the toxicity data were not enough.

Legal basis: On the Food Standards Agency's approved list for Great Britain. Also one of the 14 allergens that UK labelling law requires to be declared.
Permitted foods: Dried fruit (apricots, raisins, figs, prunes) · Wine and other grape drinks · Beer and cider · Fruit juices and soft drinks · Pickles and condiments (mustard, ketchup) · Sausages and burger meat with at least 4% vegetable or cereal · Dried and pre-cut potatoes, frozen raw potato products · Fresh and frozen prawns
Maximum levels: Depends on the food: up to 2,000mg per kg in pale dried fruit such as apricots, 1,500mg per kg in sultanas and raisins, 150mg per litre in dry red wine, up to 400mg per litre in some sweet wines, and 450mg per kg in breakfast sausages with at least 4% vegetable or cereal. It must be declared as an allergen above 10mg per kg or per litre.
History: European reviewers set a temporary daily limit in 2016, noting intake was already over it. In 2022, after makers did not supply the extra toxicity data requested, they withdrew it, said the data were not enough to set a new one, and flagged a possible concern at high intakes for most age groups. A 2025 European update estimated intake under alternative lower maximum levels. Sulphites are on the UK list of 14 allergens, which must be declared above 10mg per kg or per litre.

Who should be careful

People with asthma, especially poorly controlled or steroid-treated asthma, are most at risk of breathing reactions. Anyone who has reacted to sulphites before should avoid it. On UK labels look for sulphites, sulphur dioxide or E220 to E228, highlighted in the ingredients. Our allergen checker looks for those same sulphite terms in the ingredient data we hold for a scanned pack, though the packet in your hand is always the final word.

The honest read

Sulphur dioxide raises two separate issues. For people with asthma, the risk from eating it is well recorded and real, which is why it is a labelled allergen. For everyone else it is less clear. European reviewers estimated in 2016 and 2022 that people who eat a lot of the foods highest in it, particularly dried fruit, may take in more than standard risk benchmarks allow. They could not finish a full assessment because makers did not supply the data they asked for, so they worked with what they had, which they called inadequate. The nervous system signals behind the 2022 assessment come from animal studies. The additive is approved and widely used, and the regulatory science is unfinished. In 2026 a large French study also linked sulphites as a group to 12% more cancer.

Common questions about sulphur dioxide

Is E220 banned in the UK?

No. E220 is approved in the UK in foods including dried fruit, wine, sausages and pickles. It is one of the 14 allergens and must be declared above 10mg per kg or per litre.

Why was the daily limit for sulphur dioxide withdrawn?

In 2016 European reviewers set a temporary limit, noting the data were not enough for a solid assessment, and makers were asked for more toxicity studies. When none came, the 2022 follow-up concluded the data were still too incomplete to set any limit and withdrew the temporary one. Using a margin-of-exposure approach instead, reviewers found a possible concern at high intakes for most age groups.

What foods contain E220?

The most is usually in pale dried fruit, especially dried apricots, where it keeps the bright orange colour. It is also in wine, beer, cider, fruit juices, sausages and burgers with added vegetable or cereal, pickles, mustard, dried and frozen potato products, and fresh or frozen prawns.

Is E220 vegan?

The gas itself is made from sulphur, not from animals. But wine and cider it is used in may be cleared with animal products such as casein, egg white or isinglass, which are separate from the sulphur dioxide. The additive is vegan, the product may not be.