E221 – Sodium sulfite | asthma risk, side effects and food uses

Quick analysis summary about E221 – Sodium sulfite food additive

Bottom line about E221

E221 is graded ORANGE – SOME CONCERNS. Most people tolerate permitted amounts, but sensitive consumers can react and high consumers may have a low safety margin.

Why this grade for E221

Human sensitivity is documented, especially in asthma. EFSA withdrew the temporary ADI because data were inadequate, and its 2025 update still found high-consumer scenarios below the target safety margin.[1,2]

Who may want to limit or avoid E221

People with asthma, known sulfite sensitivity, or previous reactions should be cautious. Severe reactions are uncommon but possible.[3]

Common uses and where E221 appears

E221 limits browning, oxidation, and microbial spoilage in dried fruit, wine, some potato products, crustaceans, and preserved vegetables.

E221 source or origin

Sodium sulfite is a synthetic inorganic salt made from sulfur dioxide and a sodium alkali. It may be anhydrous or heptahydrate.

Intake note for E221

JECFA retains a group ADI of 0–0.7 mg/kg body weight as sulfur dioxide. EFSA withdrew its temporary ADI, uses a target margin of 80, and still found below-target high-exposure scenarios in 2025.[1,2]

Is E221 banned anywhere?

E221 is authorized in the European Union and conditionally permitted in the United States. US rules exclude meats, vitamin B1-source foods, and raw or fresh produce sold directly to consumers. No clear blanket food-use ban was identified in the other reviewed major jurisdictions.

Safety grading ORANGE – SOME CONCERNS

E221 is permitted and usually tolerated, but clinically established sensitivity and uncertain high-consumer exposure justify ORANGE.

Study basis or key toxicological reasoning for E221

EFSA selected a BMDL (Benchmark Dose Lower Confidence Limit) of 38 mg sulfur dioxide equivalents/kg body weight per day from a five-week gavage study in male Wistar rats. Prolonged visual-evoked-potential latency was the critical endpoint, with no effect at 7 mg/kg per day.[1] In 2025, refined 95th-percentile exposure reached 1.40 mg/kg per day in toddlers, implying a margin below 80.[2] An eight-week drinking-water study of sodium metabisulfite found gastric lesions at 350 mg/kg per day for three weeks then 175 mg/kg per day for five weeks. The NOEL (No Observed Effect Level) was 70 mg sulfur dioxide equivalents/kg per day.[4] These related-salt studies provide indirect group evidence for E221. A controlled challenge confirmed reactions in 4 of 20 children with steroid-dependent asthma.[5] An E221-specific human-lymphocyte study found chromosome aberrations and micronuclei mainly at high in-vitro concentrations.[6] EFSA’s broader guideline-compliant dataset was negative overall, making this a limited genotoxic uncertainty rather than evidence of dietary cancer.[1] EFSA noted testicular findings in animal studies of insufficient reliability, leaving reproduction unresolved.[1] In-vitro microbiome changes require human confirmation.[7,8]

Side effects of E221 – Sodium sulfite food additive

Breathing reactions: Sensitive people, particularly some with asthma, may develop wheezing, coughing, chest tightness, or bronchospasm.
Skin and systemic reactions: Susceptible consumers may develop hives, flushing, swelling, or rarely a severe allergy-like reaction.
Digestive symptoms: Some sensitive people report abdominal discomfort, nausea, or diarrhoea after sulfite exposure.
Vitamin B1 loss: Sulfites can destroy thiamine, which is why US rules prohibit sodium sulfite in foods recognized as vitamin B1 sources.
High habitual intake: Frequent consumption of several sulfited foods can reduce the exposure margin, although not every high consumer develops symptoms.

Should You Avoid E221 – Sodium sulfite food additive?

Most people do not need to eliminate every food containing E221. People with diagnosed sulfite sensitivity or asthma linked to sulfites should read ingredient lists and follow medical advice. Dried fruit, wine, cordials, potato products, preserved vegetables, and crustaceans can be important sources. Other consumers may still moderate frequent intake of highly sulfited products because EFSA could not establish a new ADI. A reaction history matters more than the E-number alone.

Common uses of E221 – Sodium sulfite food additive

Dried fruit: Helps limit browning and preserve a lighter colour during storage.
Wine, cider, and some beverages: Restrains oxidation and unwanted microbial growth.
Potato products: Helps prevent enzymatic darkening in selected processed products.
Crustaceans: May reduce black spot formation under regulated use conditions.
Preserved vegetables and mushrooms: Supports colour retention and shelf life in permitted products.
Food ingredients and syrups: Can act as an antioxidant or processing preservative where regulations allow it.

Common names and synonyms of E221 – Sodium sulfite food additive

Sodium sulfite
Sodium sulphite
Disodium sulfite
Sulfurous acid, disodium salt
INS 221
Na2SO3
Sodium sulfite heptahydrate

What is E221 – Sodium sulfite food additive?

E221 is sodium sulfite, an inorganic sodium salt of sulfurous acid with the formula Na2SO3. It acts as a preservative and antioxidant by slowing colour changes, flavour deterioration, and some microbial spoilage.

Food-grade sodium sulfite is produced by reacting sulfur dioxide with sodium hydroxide or sodium carbonate, followed by purification and crystallization. The EU specification covers anhydrous sodium sulfite and sodium sulfite heptahydrate. These are forms of one additive, not E221(i) and E221(ii) subtypes.

Sulfite species interconvert with pH, so regulators assess E220–E228 as sulfur dioxide equivalents. Most absorbed sulfite is converted to sulfate and excreted, but sensitivity varies. Sulfites can degrade thiamine and are restricted in vitamin B1-source foods. Laboratory microbiome and genotoxicity findings do not directly reproduce ordinary dietary exposure.[1,6-8]

Where is E221 – Sodium sulfite food additive allowed (EU vs US)?

E221 is currently authorized in the European Union in specified food categories and at defined maximum levels. In the United States, sodium sulfite is generally recognized as safe under good manufacturing practice, except in meats, vitamin B1-source foods, and raw or fresh fruits and vegetables intended for direct consumption. Sulfite labeling requirements also apply when regulatory thresholds are met.

E221 – Sodium sulfite