Caramel Color IV vs Yellow Dye 5: which is worse?

What is Caramel Color IV?

Caramel Color IV (Class IV caramel, E150d) is a food coloring made by heating sugar with both ammonium and sulfite compounds. This production method creates a unique set of reactive byproducts, notably 4-methylimidazole (4-MEI), which has been linked to cancer in animal studies. It is the most widely used caramel coloring in beverages like Coca-Cola and Pepsi.

What is Yellow Dye 5?

Yellow Dye 5 (tartrazine) is a synthetic lemon-yellow azo dye derived from petroleum. It produces a bright, stable yellow color in acidic conditions and is one of the most widely used yellow dyes globally. Its chemical formula is C16H9N4Na3O9S2.

Documented risks

Caramel Color IV: The primary concern with Caramel Color IV is 4-methylimidazole (4-MEI), a byproduct of the ammonia-sulfite caramel production process. The National Toxicology Program (NTP) found that 4-MEI caused lung cancer in male and female mice at high doses in 2-year bioassay studies, leading to California listing 4-MEI as a known carcinogen under Proposition 65 in 2011. The Prop 65 safe harbor level is 29 micrograms 4-MEI per day (the level that would cause 1 additional cancer per 100,000 people over a 70-year lifetime). CSPI testing in 2011-2012 found Coca-Cola and Pepsi sold in California contained 4-MEI levels that, at typical consumption rates, would exceed this threshold — triggering voluntary reformulation by both companies to reduce 4-MEI in their US products. The FDA reviewed 4-MEI and concluded that typical exposure levels 'are not a safety concern.' EFSA's evaluation found the NTP findings concerning but noted the margin of safety at typical European exposure levels. The cancer mechanism in mice involves high doses that may not extrapolate to typical human cola consumption.

Yellow Dye 5: Yellow Dye 5 was one of six dyes studied in the landmark 2007 McCann et al. study in The Lancet. The study found statistically significant increases in hyperactivity in children ages 3 and 8–9 given a mixture containing tartrazine and sodium benzoate. EFSA reviewed the evidence and confirmed the effect was real, mandating the EU warning label from 2010. A 2012 review in Neurotherapeutics (Arnold et al.) confirmed that artificial food colors including tartrazine have a small but statistically significant adverse effect on children's behavior that is not confined to those with diagnosed ADHD. Tartrazine is one of the most documented causes of food dye hypersensitivity. Cross-reactivity with aspirin (acetylsalicylic acid, ASA) is well established in allergy literature: individuals with aspirin hypersensitivity have elevated risk of reacting to tartrazine. Symptoms include urticaria, angioedema, rhinitis, and in rare cases anaphylaxis. Prevalence of tartrazine sensitivity is estimated at 0.1% of the population but higher in aspirin-sensitive individuals. Because of this known hypersensitivity risk, the FDA specifically requires Yellow No. 5 to be declared by name on US food labels — an exceptional requirement not applied to most other additives, reflecting the FDA's acknowledgment of this real clinical concern. EFSA's 2009 re-evaluation found no evidence of genotoxicity in standard test systems at food use levels, setting an ADI of 7.5 mg/kg body weight, but noted in vitro evidence at higher doses. In April 2025, the FDA announced plans to phase out Yellow 5 along with other petroleum-based dyes.