What is E223?

Complete guide to understanding E223 (Sodium Metabisulfite) in your food

The Quick Answer

E223 is sodium metabisulfite—a sodium salt of sulfurous acid that functions as a preservative, antioxidant, and bleaching agent in dried fruits, vegetables, wines, and other foods by releasing sulfur dioxide to prevent spoilage, oxidation, and discoloration.

CRITICAL SAFETY WARNING: E223 is part of the sulfite family (E220-E228) which carries well-documented health risks, particularly for asthmatics. Clinical research confirms 3-10% of chronic asthmatics experience adverse respiratory reactions when exposed to sulfites. Key documented concerns include: (1) bronchial constriction, wheezing, and respiratory distress in 3-10% of chronic asthmatics—with some experiencing life-threatening reactions; (2) steroid-dependent asthmatics and those with marked airway hyperresponsiveness at significantly elevated risk; (3) documented anaphylactic shock and severe allergic-like reactions in sensitive individuals; (4) symptoms ranging from mild in some to life-threatening in others; (5) vitamin B1 destruction; (6) promotion of harmful gut bacteria (Desulfovibrio) potentially causing inflammatory bowel disease; (7) acute toxicity rated as “Acute Tox. 4 (oral)” with moderate toxicity; (8) reactions do not respond to antihistamines—avoidance is only management strategy. E223 should be strictly avoided by all asthmatics, steroid-dependent patients, and those with documented sulfite sensitivity.

What Exactly Is It?

E223 is sodium metabisulfite—a sodium salt of sulfurous acid produced by combining sulfur dioxide with sodium carbonate or sodium hydroxide, functioning as a powerful reducing agent and antimicrobial preservative by releasing sulfur dioxide gas when dissolved.

Chemical formula: Na₂S₂O₅ (also called sodium pyrosulfite or sodium disulfite); molecular weight 190.10 g/mol.

E223 appears as white powder with pungent sulfur dioxide odor. It is soluble in water (54 g/100 ml at 20°C; 81.7 g/100 ml at 100°C), with aqueous pH 4.0-5.5 (acidic).

Critical chemical reaction: When dissolved in water, sodium metabisulfite dissociates and releases sodium bisulfite (NaHSO₃) and sulfur dioxide (SO₂) gas:

Na₂S₂O₅ + H₂O → 2 NaHSO₃ → sulfurous acid + SO₂ gas

Production: SO₂ + Na₂CO₃ (or NaOH or Na₂SO₃) → Na₂S₂O₅. Industrially produced; China major manufacturer.

Mechanism: Released SO₂ gas and sulfurous acid in acidic conditions disrupt microbial metabolism, inhibit growth of bacteria/yeasts/molds, and act as powerful oxygen scavengers preventing oxidation/browning/rancidity.

Where You’ll Find It

E223 (and the broader sulfite family E220-E228) is widely used despite documented health risks:

• Dried fruits (apricots, raisins, figs, dates; major use)
• Dried vegetables (mushrooms, peppers, carrots)
• Fresh and frozen vegetables (maintains color)
• Wine (prevents unwanted fermentation; major use)
• Jams, preserves, and jellies
• Grape juice
• Glucose and sugar syrups
• Processed meats and canned seafood
• Canned fruits and vegetables
• Mushroom preparations and mushroom supplements
• Vegetable salads (prevents fermentation and browning)
• Coconut cream (bleaching agent)
• Beer and some beverages
• Food colorants and food-grade chemicals

Maximum use levels: 10-2000 mg/kg depending on food category. Residual SO₂ strictly regulated.

Is It Safe?

NO—Not for asthmatics. E223 carries well-documented clinical risks, particularly for asthmatics. While FDA/EFSA/JECFA technically approve it, clinical evidence is overwhelming: 3-10% of chronic asthmatics experience adverse reactions, including life-threatening bronchospasm and anaphylaxis. EFSA has TEMPORARILY set the ADI pending re-evaluation due to uncertainties and safety concerns. This is NOT a “safe” additive for this vulnerable population.

EFSA’s position (2016 and ongoing):

“The current group ADI of 0.7 mg expressed as SO₂ equivalent/kg bw per day for E220-E228 was TEMPORARY and would be re-evaluated due to uncertainties and limitations in the database.”

This means EFSA does not consider the current ADI permanently safe—it is awaiting further re-evaluation.

What Are The Health Concerns?

E223 has exceptional clinical documentation of health concerns—more research exists on sulfite sensitivity than most food additives:

1. Respiratory Distress in Asthmatics (WELL-DOCUMENTED): 3-10% of chronic asthma patients experience adverse respiratory reactions when exposed to sulfites. This is the most common and well-researched adverse effect. Symptoms include bronchial constriction, wheezing, chest tightness, coughing, dyspnea (shortness of breath), and respiratory distress.

2. Life-Threatening Reactions in Asthmatics (DOCUMENTED): Some asthmatic individuals experience severe, life-threatening bronchospasm requiring emergency treatment. In some cases, delayed recovery required three weeks of corticosteroid therapy and multiple emergency department visits.

3. High-Risk Asthmatic Subgroups (IDENTIFIED): Steroid-dependent asthmatics and those with marked airway hyperresponsiveness are at substantially elevated risk. Children with chronic asthma also appear at greater risk than adults.

4. Occupational Asthma (CONFIRMED): Workers handling sodium bisulfite/metabisulfite experience bronchospasm requiring hospitalization. Occupational asthma well-documented in photographic technicians and radiographers. Pulp mill workers exposed to SO₂ show increased incidence of asthma and increased asthma-related mortality.

5. Anaphylactic Shock (DOCUMENTED): Anaphylactic reactions have been reported following exposure to sulfites, representing life-threatening reactions. While not common, documented cases exist.

6. Diverse Sensitivity Symptoms (DOCUMENTED): Beyond respiratory symptoms, sulfite sensitivity triggers:

• Dermatitis and skin rash
• Urticaria (hives)
• Flushing
• Hypotension (low blood pressure)
• Abdominal pain and cramping
• Diarrhea and gastrointestinal distress
• Vomiting
• Angioedema (dangerous swelling)
• Nasal congestion
• Sneezing
• Throat symptoms

7. Sex and Age Differences (IDENTIFIED): Research suggests sulfite sensitivity may be more common in women and children than men.

8. Asthma-Sulfite Sensitivity Link (WELL-ESTABLISHED): Sulfite sensitivity disproportionately affects people with asthma. While adverse reactions extremely rare in non-asthmatic subjects, they occur commonly in asthmatics.

9. Multiple Mechanisms of Action (PROPOSED BUT UNCLEAR): Several biological mechanisms likely explain sulfite sensitivity, including:

• Parasympathetic system stimulation with cholinergic-mediated bronchoconstriction
• Inadequate sulfite oxidase enzyme activity leading to excessive sulfite accumulation
• Mast cell degranulation and histamine/mediator release
• Prostaglandin involvement
• Leukotriene pathway activation

The exact mechanism remains incompletely understood, but multiple pathways likely operate.

10. Dose and Exposure Form Variation (COMPLEX): Type, form, and dose of sulfite exposure affect reactions unpredictably. Nebulized bisulfite solutions, acidified metabisulfite solutions, encapsulated metabisulfite, and sulfite-containing food/drinks may or may not trigger reactions in the same individual.

11. Non-Asthmatic Sensitivity (RARE BUT REAL): While adverse reactions extremely rare in non-asthmatics, some cases documented.

12. Vitamin B1 Destruction: Sodium metabisulfite destroys thiamine (vitamin B1), reducing nutritional value of foods.

13. Gut Dysbiosis (EMERGING CONCERN): Sulfur-reducing bacteria (Desulfovibrio) proliferate on sulfite compounds, potentially damaging intestinal mucosa and promoting inflammatory bowel disease.

14. Acute Toxicity (CHEMICAL HAZARD): Classified as “Acute Tox. 4 (oral)” indicating moderate toxicity after single ingestion. Safety data sheet indicates moderate toxicity concerns.

15. Eye Damage (CHEMICAL HAZARD): Direct contact causes serious, potentially irreversible eye damage.

16. Antihistamine Resistance (TREATMENT IMPLICATION): Sulfite sensitivity reactions do NOT respond to standard antihistamine treatment—avoidance is the only effective management strategy.

Chronic vs. Acute Exposure

Research identifies both acute and chronic concerns:

Acute Exposure: Episodic and acute symptoms following consumption of sulfite-containing foods (dried fruits, wines) or use of sulfite-containing cosmetics/medications. Severe reactions can occur acutely.

Chronic Exposure: Sensitive individuals regularly consuming sulfite-containing products or using sulfite cosmetics/medications may experience chronic symptoms. Chronic skin symptoms reported on hands, face, and perineum. Possibility that regular unrecognized exposure contributes to chronic asthma symptoms in sensitive individuals.

Regulatory Status and Inconsistencies

E223 is approved despite well-documented clinical concerns:

• FDA: GRAS (Generally Recognized as Safe)
• EFSA: Approved BUT ADI “temporary” and pending re-evaluation due to “uncertainties and limitations in database”
• JECFA: ADI 0-0.7 mg/kg set 1998; approved
• Mandatory allergen labeling: Sulfites one of only 14 major allergens in UK, reflecting serious regulatory concern
• Clinical evidence: 280+ medical publications documenting adverse effects, yet approval continues

Natural Alternatives

Want to avoid E223 and sulfites?

• Sorbic acid (E200) or potassium sorbate (E202) – alternative preservatives without asthma trigger concerns
• Ascorbic acid (E300/Vitamin C) – natural antioxidant
• Rosemary extract – natural antioxidant and preservative
• Salt-based preservation – traditional method
• Refrigeration/Freezing – avoid additives entirely
• Vacuum packing and inert gas flushing – reduce oxidation without sulfites
• Fresh products – accept shorter shelf-life without preservatives

The Bottom Line

E223 (Sodium Metabisulfite) is an approved preservative that carries serious, well-documented clinical health risks, particularly for asthmatics. Research over decades confirms 3-10% of chronic asthmatics experience adverse respiratory reactions, with some experiencing life-threatening bronchospasm and anaphylaxis. Steroid-dependent asthmatics and those with marked airway hyperresponsiveness face significantly elevated risk. EFSA considers the current ADI temporary and pending re-evaluation due to uncertainties and limitations. Documented occupational asthma, chronic symptoms from prolonged exposure, and vitamin B1 destruction add to concerns. Mandatory allergen labeling as one of 14 major allergens reflects regulatory acknowledgment of serious risks. E223 should be strictly avoided by all asthmatics, steroid-dependent patients, and individuals with documented sulfite sensitivity. The 280+ medical publications documenting adverse effects represent exceptional clinical evidence—more extensive than most food additives.

Clinical Evidence Strength: 280+ medical publications; well-researched; 3-10% of asthmatics affected.

Documented Respiratory Risk in Asthmatics: Bronchial constriction, wheezing, chest tightness, dyspnea, respiratory distress in 3-10% of chronic asthmatics; life-threatening bronchospasm documented; occupational asthma confirmed.

High-Risk Subgroups (CLEARLY IDENTIFIED): Steroid-dependent asthmatics; marked airway hyperresponsiveness; children with chronic asthma; women possibly higher risk than men.

Documented Allergic-Type Reactions: Anaphylaxis (life-threatening), urticaria, hives, swelling, skin reactions, gastrointestinal symptoms.

Occupational Hazard (PROVEN): Workers handling metabisulfite experience bronchospasm and hospitalization; pulp mill workers show increased asthma incidence and asthma mortality from SO₂ exposure.

Chronic Exposure Concerns: Chronic skin and respiratory symptoms from prolonged exposure; possible contribution to chronic asthma symptoms in sensitive individuals.

EFSA Temporary ADI Status: Current ADI pending re-evaluation; EFSA acknowledges uncertainties and limitations in safety database.

Vitamin B1 Destruction: Reduces nutritional value of foods.

Gut Health Concern (EMERGING): Promotes harmful bacteria (Desulfovibrio) potentially causing inflammatory bowel disease.

Antihistamine Resistance: Reactions do not respond to standard treatments; avoidance only effective strategy.

Mandatory Allergen Labeling: One of 14 major allergens in UK.

Chemical Hazards: Acute toxicity rated “Acute Tox. 4 (oral)”; causes serious eye damage.

Recommendation (VERY STRONG): E223 should be strictly avoided by all individuals with asthma, steroid dependency, marked airway hyperresponsiveness, or documented sulfite sensitivity. The combination of FDA/EFSA/JECFA approval AND well-documented clinical harm represents a serious regulatory inconsistency. EFSA’s statement that the current ADI is “temporary” and requires re-evaluation explicitly indicates current safety claims are not definitive. For the general non-asthmatic population, the extensive clinical evidence (280+ publications) and identified high-risk subgroups warrant awareness and caution. Those concerned about health should prefer alternative preservatives or fresh products, particularly when feeding children or managing asthma.