A common synthetic red dye. A UK study linked some color mixes with hyperactivity in some children; the EU now requires a warning label.
Regulation
EU products containing it carry a warning: 'may have an adverse effect on activity and attention in children'. US FDA permits it without warning.
Evidence
The Southampton study found small effects for mixtures with sodium benzoate; regulators interpreted it differently.
Evidence & sources
Mixtures of certain artificial colors plus sodium benzoate increased hyperactive behavior in some children in a randomized trial. Evidence: limited. Known: McCann et al. (Southampton study). Unknown: Clinical significance; which individual colors matter. Source: McCann et al., The Lancet, Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children (2007).