Sodium Sulfite
The short version
A sulfite preservative and antioxidant that releases SO2 to stop browning — a declared allergen above 10 mg/kg.
A sulfite preservative. It's effective, but sulfites can set off asthma and other reactions in sensitive people, so they must be declared on labels. That's why we flag it.
Where it comes from
The sodium salt of sulfurous acid, made by reacting sulfur dioxide with sodium carbonate.
How it's used
Preservative and antioxidant that releases sulfur dioxide — it inhibits browning and microbial growth in dried fruit and some processed foods, and is used as a wine and processing additive.
Safety profile
Group ADI 0.7 mg/kg body weight as SO2 (shared by the sulfites). Sulfites can trigger asthma and reactions in sensitive people; declaration is mandatory above 10 mg/kg.
Physical & chemical properties
White crystalline powder, water-soluble; slowly oxidizes in air to sulfate.
Regulation worldwide
Permitted in the EU, the US, and globally with limits and mandatory sulfite labelling.
Educational information only. Not medical or dietary advice.