Caramel Color IV vs Sodium Benzoate: 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 Sodium Benzoate?

Sodium benzoate is the sodium salt of benzoic acid (C7H5NaO2). In acidic foods and beverages, it converts to benzoic acid, which inhibits microbial growth. While benzoic acid occurs naturally in some fruits and spices at low levels, the commercial preservative is synthetically manufactured.

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.

Sodium Benzoate: Sodium benzoate's most significant documented concern is the benzene formation reaction. When sodium benzoate coexists with ascorbic acid (vitamin C) in acidic conditions, they react in the presence of metal ions (iron, copper) and UV light to produce benzene, an IARC Group 1 human carcinogen. FDA surveys in 2005-2007 found benzene exceeding the EPA drinking water standard (5 ppb) in 79 of 200 commercial beverages tested. This triggered voluntary reformulations across the beverage industry. The 2007 McCann et al. Lancet study showed that the combination of sodium benzoate with six artificial food dyes significantly increased hyperactivity in children — the effect was synergistic, with the combination producing greater behavioral effects than either ingredient alone. This finding led directly to the EU's mandatory warning label requirement for products combining sodium benzoate with specified dyes. A 2010 study in ADHD: Attention Deficit and Hyperactivity Disorders found associations between urinary sodium benzoate/hippuric acid metabolite levels and ADHD symptom severity in children, independent of dye exposure. A 2019 study in Nutrients (PMC6520673) found similar associations in Korean children. Mitochondrial DNA damage: Dr. Peter Piper at the University of Sheffield found that sodium benzoate at concentrations used in some beverages could damage mitochondrial DNA in yeast cells, potentially affecting mitochondrial function. These findings have not been fully replicated in human tissue studies. Hypersensitivity reactions including urticaria, angioedema, and contact dermatitis are documented. Cross-reactivity with aspirin has been reported in aspirin-sensitive individuals.