Artificial food colouring and preservatives commonly found in many of the foods children regularly eat appear to lead to increased levels of hyperactivity, finds a study in The Lancet.
The study found that it wasn't just children with attention deficit hyperactivity disorder (ADHD) who were affected, but all the children had trouble with inattention, impulsivity, and overactivity.
A team led by Jim Stevenson of the University of Southampton in Southampton, UK, had 153 three-year-old children and 144 children aged eight or nine years consume one of three fruit drinks:
- Mix A, which contained artificial food colouring;
- Mix B, which contained the preservative sodium benzoate and artificial food colouring;
- or a placebo drink.
The food colourings used were: tartrazine, sunset yellow, carmoisine, and ponceau. All but carmoisine are permitted for use in Canada. The amounts of the chemicals in each drink were adjusted for each of the two age groups.
Behaviours were measured by a "global hyperactivity aggregate" based on ratings by teachers and parents, plus a computerized test that measured attention spans for the older age group.
The researchers found that, among the three-year-old children, mix A had a significantly adverse effect on hyperactivity compared with placebo in GHA.
The effects for mix B were mixed, with greater variability in the response to the active challenges than placebo in this group.
Among the eight and nine-year-old children, they showed a significantly adverse effect when given mix A or mix B.
The researchers note that increased hyperactivity is associated with the development of educational difficulties, especially in relation to reading.
"This study provides evidence of deleterious effects of (artificial food colours and additives) on children's behaviour," the authors write, while adding that it remains unclear which specific compounds in their drink mixed were responsible for the behaviour changes. They say that should be further investigated in subsequent studies.
They say further investigation would also need to establish whether the age-related difference noted in their study -- i.e.: the effects of mix A being greater for three-year-old children than for the older children -- can be replicated.
Several hours after the study's release, Britain's Food Standards Agency issued a warning urging parents of hyperactive children to avoid foods with multiple additives.
Dr Andrew Wadge, the FSA's Chief Scientist, said: "This study is a helpful additional contribution to our knowledge of the possible effects of artificial food colours on children's behaviour.
"After considering the (Committee on Toxicity's) opinion on the research findings we have revised our advice to consumers: if a child shows signs of hyperactivity or Attention Deficit Hyperactivity Disorder (ADHD) then eliminating the colours used in the Southampton study from their diet might have some beneficial effects.
"However, we need to remember that there are many factors associated with hyperactive behaviour in children. These are thought to include genetic factors, being born prematurely, or environment and upbringing."
