Sulfites
E220-228
Sulfur-based preservatives that stop browning and spoilage — but trigger asthma in a sensitive minority
Moderate evidence
🍬Sweeteners & Additives
Evidence tier
Moderate
Research weight
Citations
10 verified / 10
Classification
Sweeteners & Additives
❝
What the evidence says. Several controlled trials; effects real but modest or context-dependent.
What is Sulfites?
Sulfites (E220-228) is a sweetener or food additive used for prevents enzymatic and non-enzymatic browning (e.g. keeps dried apricots, shrimp and cut potatoes light-colored). NutriDex grades the human evidence as Moderate. Sulfites (sulfur dioxide and its salts, E220-E228) are antioxidant/antimicrobial preservatives used in wine, dried fruit, processed potatoes, fruit juices and many other foods, releasing SO2 to inhibit browning, oxidation and microbial spoilage. They are permitted in the US (where they remain GRAS for most uses but are banned on raw fruits and vegetables) and the EU. For the general population the human evidence is broadly reassuring at typical intakes, and the principal, well-documented health concern is dose-related asthmatic/hypersensitivity reactions in a sensitive minority (~3-5% of asthmatics); EFSA in 2022 withdrew the prior ADI because the toxicology database (including a neurotoxicity signal in animals) was judged inadequate, flagging a possible safety concern for high consumers.
Purported Benefits
✓Prevents enzymatic and non-enzymatic browning (e.g. keeps dried apricots, shrimp and cut potatoes light-colored)
✓Antimicrobial preservative — inhibits bacteria, yeasts and molds, central to winemaking and juice stability
✓Antioxidant — scavenges oxygen and stabilizes color, flavor and ascorbic acid in foods and beverages
✓Extends shelf life of dried fruits, vegetables and fruit-based products
✓Used as a processing aid and bleaching/dough-conditioning agent in some starches and baked goods
Dosing & Compounds
Typical Dose
JECFA and the prior EFSA assessment set a group Acceptable Daily Intake of 0-0.7 mg SO2-equivalents/kg body weight/day (derived from a rat NOAEL of ~70 mg SO2-eq/kg/day with a 100x uncertainty factor). EFSA's 2016 re-evaluation made this ADI temporary, and in 2022 EFSA withdrew it because adequate toxicity data were lacking, instead using a margin-of-exposure approach and finding a possible safety concern for high consumers. In the US sulfites are GRAS for most uses but FDA prohibits them on fruits and vegetables intended to be served or sold raw (since 1986) and requires label declaration when total SO2 is >=10 ppm.
Active Compounds
Safety & Cautions
The best-established harm is dose-dependent sulfite sensitivity, mainly bronchoconstriction in asthmatics (roughly 3-5% of asthmatics, more in steroid-dependent patients), and less commonly urticaria, angioedema or anaphylaxis; this is a non-IgE pharmacological/irritant reaction, not classic allergy. Severe and occasionally fatal asthma reactions to sulfite-treated fresh produce led the FDA to ban sulfites on raw fruits and vegetables in 1986 and mandate labeling at >=10 ppm. People with asthma (especially sulfite-sensitive) should avoid them; rare individuals with molybdenum-cofactor/sulfite-oxidase deficiency are especially vulnerable. Sulfites also chemically cleave and destroy thiamine (vitamin B1), so they are not permitted in foods regarded as major thiamine sources. For the general population, intake at usual levels is not associated with clear systemic toxicity, but EFSA's 2022 review flagged unresolved data gaps including a neurotoxicity signal in animal studies, prompting withdrawal of the ADI rather than a finding of proven harm. Educational only — always check with your doctor or pharmacist before combining Sulfites with any medicine.
Key Studies ★ 10 studies
regulatory
EFSA FAF Panel 2022
✓ Full text
Follow-up withdrew the ADI because data gaps (including a neurotoxicity signal in animals) could not be resolved; margin-of-exposure analysis indicated a possible safety concern for high consumers.
RCT
Bassani 2026
✓ PubMed
Driving-simulator study of driver behaviour after consuming conventional wines with different sulphite contents.
regulatory
EFSA ANS Panel 2016
✓ Source
Re-evaluation set a temporary group ADI of 0.7 mg SO2-equivalents/kg bw/day (NOAEL 70 mg/kg/day in rats) and judged the toxicity database inadequate for a permanent ADI.
regulatory
JECFA (WHO Food Additives Series 42)
✓ Source
Retained a group ADI of 0-0.7 mg/kg bw expressed as SO2, based on a NOEL of ~70 mg SO2-eq/kg/day from long-term and reproductive rat studies.
regulatory
US FDA 21 CFR (sulfite ban & labeling)
✓ Source
FDA prohibited sulfites on fruits and vegetables intended to be served or sold raw and required declaration of added sulfites at >=10 ppm total SO2, citing severe asthmatic reactions.
Review
Lisboa 2026
✓ PubMed
Exposure, fate and impact of food preservatives in the environment
review
Vally & Misso (review)
✓ Full text
Summarized adverse reactions to sulphite additives, estimating sulfite sensitivity in a minority of asthmatics and noting non-IgE mechanisms.
review
Vally, Misso & Madan (review)
✓ PubMed
Reviewed clinical effects of sulphite additives, characterizing dose-related bronchoconstriction in sulfite-sensitive asthmatics and rarer urticaria/anaphylaxis as the principal documented adverse reactions.
clinical study
Bush, Taylor & Busse (prevalence study)
✓ PubMed
Oral metabisulfite challenge found sensitivity in about 5% of asthmatic patients, with higher rates among steroid-dependent asthmatics.
mechanistic
Leichter & Joslyn (thiamine cleavage kinetics)
✓ Full text
Demonstrated that sulfite cleaves thiamine (vitamin B1) at its methylene bridge, inactivating it — the basis for prohibiting sulfites in major dietary thiamine sources.