Common food additives and colorings can increase hyperactive behavior in a broad range of children, according to a study released Thursday.
It was the first time researchers have scientifically confirmed a link that has long been suspected by many parents.
Support groups for those who suffer from Attention Deficit Hyperactivity Disorder have long recommended removing the artificial colors and preservatives such as sodium benzoate from diets, although experts still debate the evidence.
But the carefully controlled study showed that artificial additives increase hyperactivity and decrease attention in a wide range of children, not just those for whom overactivity is a diagnosed learning problem.
The research, which was financed by the British Food Safety Agency and published online by the British medical journal the Lancet, presents regulators with a number of dilemmas: Should foods containing preservatives and artificial colors carry special warning labels? Should some additives be prohibited entirely? Should schools remove foods with additives from school cafeterias?
The researchers note that overactive children have a harder time learning.
"A mix of additives commonly found in children's foods increases the mean level of hyperactivity," wrote the researchers, who were led by Jim Stevenson at the University of Southampton. "The finding lends strong support for the case that food additives exacerbate hyperactive behaviors (inattention, impulsivity, and overactivity) at least into middle childhood."
The Lancet study focuses on sodium benzoate, a common preservative, and a variety of colorings.
The study did not try to link specific substances with specific behaviors.