Yellow Dye 6 vs Sucralose: which is worse?

What is Yellow Dye 6?

Yellow Dye 6 (Sunset Yellow FCF) is a synthetic orange-yellow azo dye derived from petroleum. It produces a bright orange-yellow color and is structurally similar to Yellow 5 but produces a more orange shade. Its chemical formula is C16H10N2Na2O7S2.

What is Sucralose?

Sucralose is a synthetic non-caloric sweetener made by selectively chlorinating three hydroxyl groups in sucrose (table sugar). Despite being derived from sugar, the chlorination makes it non-digestible: most passes through the body without being metabolized. It is approximately 600 times sweeter than sucrose.

Documented risks

Yellow Dye 6: Yellow Dye 6 was included in the 2007 Lancet study (McCann et al.), which found that a mixture of six dyes including Yellow 6 and sodium benzoate significantly increased hyperactivity in children. EFSA confirmed the effect warranted mandatory warning labels in the EU. EFSA's 2009 re-evaluation examined animal carcinogenicity data and found some studies showing adrenal tumors in male mice at high doses. EFSA set an ADI of 2.5 mg/kg body weight — lower than Yellow 5's ADI of 7.5 mg/kg, reflecting greater concern. The review noted limitations in the available data. Impurity concerns: commercial batches of Yellow 6 have been found to contain aromatic amine impurities including benzidine and 4-aminobiphenyl — both IARC Group 1 human carcinogens. A 1992 CSPI analysis documented these impurities, citing them as reason for concern. A 2007 study in Toxicological Sciences found Yellow 6 altered zinc and iron biomarker levels in rat blood at high doses, raising mineral metabolism concerns. Human relevance at typical exposure is unclear. Hypersensitivity reactions including urticaria, rhinitis, and contact dermatitis are documented. Cross-reactivity with aspirin is reported similarly to Yellow 5. In April 2025, the FDA announced plans to phase out Yellow 6 with other petroleum-based dyes.

Sucralose: A 2023 study published in Nature Medicine found that sucralose-1,6-hexanediacid — a gut-derived metabolite of sucralose — enhanced T-cell immune activity in vitro. The researchers found that sucralose exposure in certain doses could potentially affect immune function. However, this was an early-stage study and its clinical implications for humans are not established. A 2021 Cell study found that sucralose and other non-nutritive sweeteners altered gut microbiome composition and glucose tolerance in human participants who were non-habitual sweetener users. The study found sucralose consumption was associated with glucose intolerance changes in some individuals, suggesting gut microbiome-mediated effects on metabolism. A 2016 study in the International Journal of Occupational and Environmental Health found sucralose consumption was associated with higher leukemia incidence in male mice at high lifetime doses. This finding prompted significant concern, though regulators noted the doses used far exceeded typical human intake. Chlorinated compounds: sucralose contains chlorine atoms in its structure. Critics have argued this makes it similar to organochlorine compounds, some of which are known carcinogens. Regulatory agencies have reviewed this and do not consider the chlorine in sucralose equivalent to organochlorine pollutants; the chlorinated positions are not metabolically active. However, high-temperature cooking with sucralose can generate chlorinated compounds. EFSA's 2017 re-evaluation concluded sucralose is safe and non-carcinogenic at its ADI of 15 mg/kg body weight. The FDA ADI of 5 mg/kg/day provides a substantial safety margin relative to typical consumer intake from Splenda use.