E-numbers / E226 Preservative

Calcium sulphite

also: Calcium sulfite · E226

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The short version

A calcium-based sulphite preservative that stops bacteria, mould and yeast growing in food and drink.

Why it's worth knowing

Sulphites trigger breathing difficulties in around 5 to 13 percent of people with asthma. EFSA withdrew its safety benchmark in 2022 because evidence suggests high-end dietary intake may exceed levels considered safe for most age groups.

What is it?

Calcium sulphite is the calcium salt of sulphurous acid (CaSO3). It is a white powder that releases sulphur dioxide when it encounters heat or stomach acid, which is the active antimicrobial and antioxidant agent. It is synthetically produced and contains no animal-derived ingredients.

What does it do?

When calcium sulphite releases sulphur dioxide in food, that gas inhibits the enzymes bacteria and moulds need to reproduce, preventing spoilage. It also acts as an antioxidant, scavenging oxygen to stop cut or dried fruit browning and prevent oxidative degradation in wine and juice. In the body, sulphite is normally converted to sulphate by the enzyme sulphite oxidase and excreted in urine.

Where you will see it

Most commonly used in dried fruits such as apricots, raisins and figs to preserve colour; in fruit juices and concentrates; in ciders and fermented grape-based drinks; in preserved and canned vegetables; and in some grain and meat products. On a label it will appear as 'calcium sulphite', 'E226', or more often as the group term 'sulphites' or 'sulphur dioxide and sulphites', printed in bold as a major allergen declaration.

What the science says

Asthma and breathing reactions

Sulphites release sulphur dioxide gas when swallowed, which can travel into the airways and cause them to constrict. Somewhere between 5 and 13 percent of people with asthma experience wheezing, chest tightness or cough after eating foods with sulphites, with poorly controlled or steroid-dependent asthma carrying the highest risk. True IgE-mediated allergy is rare; most reactions are a sensitivity or intolerance rather than a classic allergic response.

Sulphite sensitivity causes bronchoconstriction, wheezing and dyspnoea primarily in asthmatics, with incidence estimated at 5 to 13 percent in that population versus under 2 percent in the general population.

Allergy UK, Sulphites and Airway Symptoms factsheet2023observational

The probable mechanism involves inhaled sulphur dioxide irritating already-reactive airways, activating both IgE pathways and cholinergic reflexes to cause bronchoconstriction.

Vally H et al., Considerations for the diagnosis and management of sulphite sensitivity, Immunology and Allergy Clinics of North America, PMC40174452014observational

EFSA withdrew its safety threshold in 2022

In 2016 EFSA set a temporary acceptable daily intake for sulphites as a group (E220 to E228, including E226). In 2022, after reviewing further evidence, EFSA concluded the toxicity data were insufficient to confirm that limit and withdrew it. Using a margin of exposure approach with a benchmark dose of 38 mg sulphur dioxide equivalents per kilogram of body weight per day, based on delayed nerve response to visual stimuli in animals, the margin fell below the safety threshold of 80 for most population groups including children and adults under both refined and maximum-permitted-level exposure scenarios.

The EFSA Panel withdrew the temporary group ADI for sulphites (E220-E228) because no new toxicological data had been submitted and the existing database was judged inadequate to derive a reliable limit.

EFSA Panel on Food Additives and Flavourings, Follow-up of the re-evaluation of sulfur dioxide and sulphites (E220-E228), EFSA Journal 2022;20(11):75942022regulatory review

Using a margin of exposure approach, margins at the 95th percentile fell below 80 for all population groups except adolescents under a refined exposure scenario, raising a safety concern.

EFSA Journal 2022;20(11):75942022regulatory review

A 2025 EFSA dietary exposure update modelled alternative maximum levels to explore which permitted-level reductions would bring MOEs above 80 across population groups.

EFSA Supporting Publications 2025, EN-97542025regulatory

Neurotoxicity signal in animal studies

The key endpoint used to set the 2022 benchmark dose was prolonged visual evoked potential latency, a measure of how long nerve signals take to travel from eye to brain, observed in animal studies at higher sulphite exposures. This signal formed the basis for a lower, more conservative reference point than the one used in 2016. The relevance of this endpoint to human dietary exposure at typical levels has not been confirmed.

Prolonged visual evoked potential latency in animal models provided the basis for a benchmark dose of 38 mg SO2 equivalents per kilogram of body weight per day, lower than the previous 70 mg reference point.

EFSA Journal 2022;20(11):75942022animal

Sulphite sensitivity in people with enzyme deficiency

The enzyme sulphite oxidase normally converts ingested sulphite to harmless sulphate for excretion. Individuals with low sulphite oxidase activity, including those with a rare inherited condition affecting this enzyme, may accumulate sulphite and react at lower exposures. The enzyme requires molybdenum as a cofactor, so molybdenum deficiency may also reduce its efficiency.

Sulphite oxidase converts sulphite to sulphate via a molybdenum-dependent reaction; individuals with reduced enzyme activity or molybdenum deficiency show heightened sensitivity to dietary sulphites.

Vally H et al., PMC4017445, Immunology and Allergy Clinics of North America2014observational

Sulphites as one of the UK's 14 major allergens

UK food law requires that sulphites and sulphur dioxide must be declared on labels in bold or otherwise emphasised text whenever they are present at more than 10mg per kg or 10mg per litre in the finished product, expressed as sulphur dioxide. This is a legal requirement for all 14 major allergens and applies to pre-packed and non-pre-packed food alike.

Sulphites are one of the 14 major allergens under retained EU food law and UK Food Information Regulations; they must be emphasised on labels when present above 10mg/kg or 10mg/litre as SO2.

UK Food Standards Agency, Food allergen labelling and information requirements technical guidance2021regulatory

Where it stands with the regulators

Status

Approved for use in the UK and EU

Legal basis

UK FSA approved-additives list and assimilated EU Regulation 1333/2008 (Annex II). Sulphites including E226 are also subject to allergen labelling requirements under retained EU food law.

Permitted foods

Dried fruits (apricots, raisins, figs and similar); Fruit juices and juice concentrates; Cider and fermented grape-based drinks; Preserved and canned vegetables; Some grain and baked products; Certain meat products (e.g. sausages and burger meat with at least 4% vegetable or cereal content, up to 450mg/kg)

Maximum levels

Varies by food category; for breakfast sausages and burger meats with at least 4% vegetable or cereal content the maximum is 450mg/kg. Other categories range from 10 to 2000mg/kg depending on product type. Specific per-category limits are set in Annex II of Regulation 1333/2008.

Safe-intake limit (ADI)

No ADI currently in force. EFSA set a temporary group ADI of 0.7mg SO2 equivalents per kilogram of body weight per day in 2016, then withdrew it in 2022 after concluding the toxicity database was insufficient to confirm it.

History

E226 belongs to the sulphite group E220-E228 that has been used in food preservation for decades. EFSA conducted a full re-evaluation in 2016 and set a temporary group ADI of 0.7mg SO2 eq/kg bw/day, noting data gaps. In its 2022 follow-up, EFSA found no new toxicological data had been provided, concluded the database remained inadequate, and withdrew the temporary ADI. Margin of exposure calculations suggested dietary intakes at the 95th percentile may pose a safety concern for most population groups. A 2025 exposure update modelled whether lower permitted maximum levels would bring margins within acceptable bounds. UK labelling rules require sulphites above 10mg/kg to be declared as a major allergen.

Who should be careful

People with asthma should exercise caution, particularly if asthma is poorly controlled or steroid-dependent, as sulphites can trigger wheezing or breathing difficulties in 5 to 13 percent of asthmatics. Anyone with a known sensitivity to sulphites or sulphur dioxide should check labels for 'sulphites', 'sulphur dioxide and sulphites' or 'E226', which must appear in bold as a declared allergen when present above 10mg/kg.

The honest read

Cutting through the noise

Sulphites are among the more scientifically scrutinised food additives. The EFSA story here is unusual: the agency set a safety limit in 2016, then formally withdrew it in 2022 not because new harms were discovered but because the industry provided no new toxicological data to shore up the limit. The 2022 assessment used a neurotoxicity endpoint from animal studies to set a reference point and found that estimated consumer intakes at the high end may fall uncomfortably close to, or below, the minimum acceptable safety margin for most age groups. That does not mean the additive is proven harmful at typical dietary exposures; it means regulators do not currently have enough data to confirm it is not. For people without asthma and without sulphite sensitivity, the science is genuinely unsettled and the regulatory picture remains open. For people with asthma, the link between sulphite intake and breathing reactions is well-documented.

Related additives

Common questions

Is E226 banned in the UK?

No. E226 is a permitted food additive in the UK under the assimilated EU Regulation 1333/2008. However, EFSA withdrew its acceptable daily intake in 2022 after industry failed to provide the toxicological data needed to confirm it, and the safety review of sulphites as a group is ongoing.

Can E226 trigger asthma or breathing problems?

Yes, in people with asthma. When sulphites are swallowed they release sulphur dioxide, which can irritate the airways and cause wheezing, chest tightness or cough. Estimates suggest 5 to 13 percent of people with asthma experience reactions. People with poorly controlled or steroid-dependent asthma are at highest risk.

What foods contain E226?

Dried fruits such as apricots, raisins and figs are among the most common sources. It also appears in fruit juice concentrates, cider and fermented grape drinks, preserved vegetables, some baked goods, and certain sausages and meat products. On the label it will usually appear as 'sulphites' or 'sulphur dioxide and sulphites' in bold, or as 'E226' or 'calcium sulphite'.

Is E226 vegan?

Yes. Calcium sulphite is a synthetically produced mineral compound. It contains no animal-derived ingredients and is suitable for vegans and vegetarians.

Sources

Last reviewed: 20 June 2026

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