Pick up certain brightly coloured sweets and you'll find a specific sentence tucked into the ingredients list: "may have an adverse effect on activity and attention in children." It's not a general health disclaimer — it's a legally required statement tied to six named colours.
Where the warning actually comes from
In 2007, a University of Southampton study funded by the UK Food Standards Agency found that a mix of six artificial food colours, combined with the preservative sodium benzoate, was associated with increased hyperactivity in children in the study group. The six colours involved — tartrazine (E102), quinoline yellow (E104), sunset yellow (E110), carmoisine (E122), ponceau 4R (E124) and allura red (E129) — became known afterwards as the "Southampton Six".
What the law actually requires
Rather than banning the six colours outright, the EU (and the UK after adopting the same rule) made the warning label mandatory from 2010: any food or drink containing one or more of them must state "may have an adverse effect on activity and attention in children" directly next to that colour's name or E-number on the ingredients list. Many manufacturers chose to reformulate with alternative colours instead of carrying the warning, which is part of why these particular E-numbers are less common in UK sweets today than they once were — though they haven't disappeared entirely.
What the warning does and doesn't tell you
It reflects an average effect measured across groups of children in a specific study, not a guaranteed reaction in every child who eats the sweet, and it applies regardless of the amount eaten. It's a precautionary disclosure rule, giving parents the information up front, rather than a claim that the product is unsafe for general sale — all six colours remain legally permitted food additives in the UK, just with this label attached.
How to check a specific sweet
Because the rule is about labelling rather than a ban, the only way to know if a particular product carries one of the six colours is to check its own ingredients list for the colour names or E-numbers above, and the warning sentence that must sit next to them if present.
Frequently asked questions
Which colours trigger this warning?
Tartrazine (E102), quinoline yellow (E104), sunset yellow (E110), carmoisine (E122), ponceau 4R (E124) and allura red (E129) — the "Southampton Six".
Is the warning legally required?
Yes, since 2010, directly next to any of these six colours on a UK or EU ingredients list.
Does it mean every child will be affected?
No — it reflects an average study finding, applied as a precautionary label regardless of individual sensitivity or amount eaten.