Sulphur dioxide
Sulphite — a major allergen, destroys vitamin B1.
- Category
- Antioxidants, Preservatives
- Acceptable daily intake
- 0.7 mg/kg body weight/day (EFSA)
- Vegan
- Yes
- Vegetarian
- Yes
What it is
Sulphur dioxide (E220) is a toxic gas at room temperature, but dissolved in water it forms sulfurous acid, an incredibly potent antimicrobial and antioxidant preservative. It has been used since the Roman era to sterilize winemaking equipment and preserve food.
How it is used in food
Stops browning and microbial growth; the ancient wine preservative.
Commonly found in- Wine and cider (prevents spoilage and oxidation)
- Dried fruits like apricots (keeps them orange instead of turning brown)
- Lemon juice concentrates
- Dehydrated potatoes
Health and safety
A genuine allergen (affects 3–10% of asthmatics) and destroys vitamin B1 (thiamine).
For the vast majority of the population, dietary sulphites are processed harmlessly by the liver into sulfates and excreted. However, for a specific subset of people (particularly those with severe asthma), sulphites can trigger terrifying and potentially fatal allergic reactions.
Asthma exacerbation and anaphylaxis
Sulphites can trigger severe respiratory distress (bronchospasm) in sensitive individuals, primarily those who already suffer from severe asthma. In extreme cases, it can cause anaphylactic shock.
Destruction of Vitamin B1 (Thiamine)
Sulphur dioxide chemically destroys Vitamin B1. For this reason, it is banned from being used in foods that are considered major sources of thiamine, such as fresh meats.
"Contains sulphites" is a mandatory allergen label globally.
Regulatory status
| Region | Status | Notes |
|---|---|---|
| Australia & New Zealand FSANZ |
Permitted, must be declared on the label | Permitted with mandatory allergen labelling. “Contains sulphites” |
| European Union EFSA / European Commission |
Permitted | Authorised for food use under EU regulations (Annex II). |
| United States FDA (Food and Drug Administration) |
Permitted, must be declared on the label | Permitted, but prohibited in fresh produce and fresh meat. “Contains sulfites” |
Identification on labels
- E-number
- E220
Also printed asSulfites · Sulfur dioxide
Alternatives to this additive
- E300: Ascorbic acid — Can replace some of the antioxidant functions of sulphites, but lacks the antimicrobial punch.
How it is made
Industrially, it is produced by burning elemental sulfur or sulfur-containing ores in the presence of oxygen.
- Combustion — Elemental sulfur is burned in air to produce sulfur dioxide gas.
- Dissolution — The gas is either compressed into a liquid for direct injection into food processes (like winemaking) or dissolved in water to form a solution.
Worth knowing
Romans burned sulphur candles in barrels to preserve wine.
Conclusion
E220 is a powerful, historic preservative that remains practically irreplaceable in winemaking and fruit drying. Because of its severe allergenic potential, any product containing more than 10 ppm of sulphites must carry a bold allergen warning.
References
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Open the appEntry last reviewed 2026-07-28.
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