Red Dye 3 vs Sodium Sulfite: which is worse?

What is Red Dye 3?

Red Dye 3 (erythrosine) is a synthetic cherry-pink fluorescent dye belonging to the xanthene class. It contains approximately 58% iodine by weight, distinguishing it from azo dyes. Its chemical formula is C20H6I4Na2O5. Approved since 1907, it is one of the oldest certified US food colorants and was notably the first synthetic food dye formally revoked by the FDA in decades.

What is Sodium Sulfite?

Sodium sulfite is an inorganic sulfite salt used as a food preservative and antioxidant. It releases sulfur dioxide when it contacts water or acid, which acts as the active antimicrobial and antioxidant agent. Part of the broader sulfite family of food additives (including sulfur dioxide E220, sodium bisulfite E222, and others).

Documented risks

Red Dye 3: The FDA revoked Red Dye 3 authorization in January 2025, marking the first synthetic food dye ban by the FDA since Red Dye 2 in 1976. The revocation was triggered by the Delaney Clause, which mandates revocation of any food additive found to cause cancer in animals regardless of dose. The carcinogenicity data stems from studies showing that high doses of erythrosine caused thyroid follicular cell tumors in male rats. The mechanism is indirect: erythrosine suppresses thyroid-stimulating hormone (TSH) feedback by elevating thyroxine (T4) levels, causing chronic TSH suppression that promotes thyroid cell proliferation and ultimately tumor formation. This is a rat-specific mechanism related to their thyroxine-binding protein system, which differs from human biology. EFSA's 2011 comprehensive safety assessment concluded erythrosine was unlikely to be genotoxic at typical food use levels and set an ADI of 0.1 mg/kg body weight — one of the lowest for any food color. EFSA restricted EU use to cocktail cherries only (max 200 mg/kg). The high iodine content (58% by weight) raises concerns for thyroid-sensitive individuals. Excessive erythrosine intake could theoretically contribute to iodine overload and thyroid disruption, particularly in individuals with hyperthyroidism or Hashimoto's disease. The FDA had been aware of the rat thyroid tumor data since 1990 but delayed action for 35 years. Advocacy groups including CSPI petitioned for a ban since 1983. The January 2025 revocation finally addressed this long-standing regulatory gap.

Sodium Sulfite: Sulfites are among the more significant food allergy/intolerance triggers. An estimated 1 in 100 people, and up to 5% of asthmatics, are sulfite-sensitive. Reactions can include urticaria, angioedema, bronchospasm, and in severe cases anaphylaxis. Sulfite-induced asthma can be severe; several deaths attributable to sulfite-triggered anaphylaxis have been documented. The FDA banned sulfites from fresh produce and restaurant salad bars in 1986 after several deaths and severe reactions were linked to sulfite-treated salads. FDA mandates that sulfite content above 10 ppm be declared on US food labels. All forms of sulfites (E220-E228) share these sensitization concerns.