Sodium bisulphite

Sodium bisulphite is a sulphiting agent — a compound that releases sulphur dioxide (SO₂) when dissolved in water or food. It functions as a preservative and antioxidant, preventing browning, inhibiting microbial growth, and extending shelf life in a wide range of foods including dried fruit, wines, dehydrated vegetables, processed potatoes, and fruit-based products.

JECFA's ADI is 0.7 mg per kilogram body weight per day expressed as SO₂ equivalents, evaluated in 1967 and shared across all sulphiting agents (E220–E228). This ADI is relatively low, reflecting the established risk of triggering asthma and allergic reactions in sensitive individuals. Sulphite-sensitive asthma affects approximately 5–10% of people with asthma, and reactions can range from mild bronchospasm to severe anaphylaxis.

Sodium bisulphite is approved globally in the EU, US (GRAS), UK, Australia, Japan, and Vietnam, but is subject to mandatory allergen labelling in the EU and most other markets — any product containing more than 10 mg/kg SO₂ equivalents must declare "contains sulphites." It is one of the 14 major allergens requiring prominent declaration in the EU. Consumers with asthma or sulphite sensitivity should check ingredient labels for E220–E228 as a group. For non-sensitive individuals, sulphiting agents present no concern at normal dietary exposures.