Sodium Metabisulfite
Also known as: Sodium pyrosulfite, E223, Sulfite preservative
The sulfite antioxidant that keeps wine and dried fruit fresh — and the most common hidden trigger of sulfite sensitivity.
In short
Sodium metabisulfite is an inorganic sulfite compound used as a preservative and antioxidant in wine, dried fruit, processed potatoes, and some medications. It works by releasing sulfur dioxide, which blocks enzymatic browning and microbial growth. For most people it is safe at regulated levels and is metabolized to sulfate and excreted; for a minority — especially those with asthma — sulfites are a genuine problem, triggering bronchoconstriction in up to 5% of asthmatics. That is why US labeling law requires sulfite declaration at 10 ppm or more. The compound has been linked to no chronic toxicity at food levels; the entire risk conversation is about acute sensitivity.
- Releases sulfur dioxide as a preservative/antioxidant
- In wine, dried fruit, potatoes, and some drugs
- Triggers reactions in up to 5% of people with asthma
- Labeling required at 10+ ppm in the US
What is Sodium Metabisulfite?
Sodium metabisulfite is the reason your dried apricots stay orange and your wine stays fresh — a cheap, effective sulfite preservative that has kept food safe for centuries. For the vast majority, it passes through unnoticed; the body converts sulfites to harmless sulfate and moves on. But for a specific, predictable minority — people with asthma — sulfites can close airways within minutes of exposure, which is why sulfites occupy a rare regulatory category: legal, ubiquitous, and label-mandated because of a sensitivity rather than a toxicity.
Where it comes from
Natural sources
- Sulfites occur naturally in fermented foods and are produced in tiny amounts by the body
- Commercial sodium metabisulfite is synthesized for consistency
How it's made
White crystalline powder; EU code E223. Used in wine, cider, dried fruit, shrimp, and pharmaceutical preparations.
What it does in products
Benefits
Food preservation and safety
strong evidencePrevents spoilage and oxidation in wine, dried fruit, and seafood — a genuine food-safety function with centuries of precedent.
Low chronic toxicity
strong evidenceExtensively reviewed by JECFA and EFSA; sulfites are rapidly metabolized and show no carcinogenic or cumulative effects at regulated levels.
Color and quality retention
strong evidencePreserves the appearance and nutritional retention (e.g., vitamin C stability) of dried and processed fruits.
Side effects & safety
Safety considerations
- Safe at regulated food levels; no specific pregnancy concerns.
- None significant.
- Not for: Known sulfite sensitivity
- Not for: Severe or unstable asthma (caution with sulfite-containing foods and drugs)
How it's used
In supplements
Not supplemented; exposure is dietary and incidental.
In skincare
Rare cosmetic antioxidant use; contact allergy reported occasionally.
Regulatory status
- GRAS for specified food uses; mandatory sulfite labeling at ≥10 ppm. Prohibited on fresh produce in the US.
- GRAS (generally recognized as safe) for food use.
- INCI name on cosmetic labels: Sodium Metabisulfite.
- Assessed for cosmetic use with sensitization caveats.
Popular products containing Sodium Metabisulfite
- Wine (industry-wide) — The standard wine antioxidantVarious · Food
- Dried apricots and fruit mixes — Preserves color in dried fruitVarious · Food
- Home-brew sanitizers (Campden tablets) — Home wine/beer making stapleVarious · Food
Product names and brands are shown for reference and belong to their respective owners.
The sulfite-sensitivity mechanism
Sulfite-sensitive asthmatics appear to generate sulfur dioxide in their airways that irritates hyperreactive bronchial tissue — sometimes through inadequate sulfite-oxidase enzyme activity. Reactions occur within minutes of ingestion or inhalation (wine is a potent trigger) and respond to bronchodilators. This is why restaurant and labeling disclosure matter more for sulfites than for most additives.
Why wine needs it
Sulfur dioxide has protected wine since Roman times: it kills unwanted bacteria and wild yeast, prevents oxidation, and stabilizes flavor. 'Sulfite-free' wines exist but are notoriously unstable. The dose in wine is low (10–350 ppm), and the reaction risk is confined to the sensitive minority.
Frequently asked questions
Am I allergic to sulfites?
True sulfite allergy is rare; sulfite sensitivity (mostly respiratory) is the real entity, concentrated in asthmatics. If wine or dried fruit triggers wheezing, that is the pattern.
Do sulfites cause wine headaches?
The evidence points more to alcohol, histamines, and tannins for most wine headaches; sulfites cause respiratory symptoms rather than classic headache in the sensitive population.
Why are sulfites banned on fresh produce?
A 1986 FDA ban followed dozens of severe reactions traced to sulfite-treated salad-bar vegetables, where spraying created high, unlabeled exposure.
The bottom line
Sodium metabisulfite is a safe, effective food preservative for the majority — with a specific, well-characterized hazard for sulfite-sensitive asthmatics that labeling rules are designed to manage.
References
- Sulfites — FDA overview. U.S. Food and Drug Administration. https://www.fda.gov/food/food-additives-petitions/sulfites
- Sulfite sensitivity in asthma. PubMed. https://pubmed.ncbi.nlm.nih.gov/31513099/
- Safety evaluation of sulfites — JECFA. WHO/FAO Joint Expert Committee. https://www.fao.org/food-safety/scientific-advice/jecfa/en/