Researchers have produced what they say is the best evidence to date that food additives aggravate hyperactive behavior in children. To many parents that's an article of faith. But numerous studies over the past 30 years have failed to provide conclusive evidence.
John Warner, a pediatric allergist at the University of Southampton, U.K., and colleagues studied what they say is the largest group of subjects ever assembled from the general population for such a study: 277 3-year-olds on the Isle of Wight, about half of whom were diagnosed with attention deficit hyperactivity disorder (ADHD). In the monthlong trial, each child spent a week drinking juice spiked with food colorings and sodium benzoate, a common preservative. After a week of drying out, they spent another week drinking identical-tasting juice with no additives. Parents were blind to the study design. The additives in the juice were "no more than what you would expect in a reasonable child's diet," says Warner.
Formal lab observations of children's behavior did not reveal any differential effect from the additives. But most parents detected significant differences--regardless of whether their child had ADHD--when asked to give weekly ratings of kids' behaviors in such realms as twitching, fiddling, talkativeness, restlessness, and difficulties in concentration, the authors report in the June issue of Archives of Diseases in Childhood. They estimate that elimination of additives might reduce the percentage of children diagnosed as "hyperactive to the point of impairing performance" from 15% to 6%.
Warner says that he himself has been "hesitant about telling parents to avoid additives," but now "I will do so." He says the U.K. Food Standards Agency will be funding a larger study by his group on older children that will include attempts to identify genes associated with the reactions to additives.
"There have been very polarized camps on this issue for a long time," says pediatrics professor Hugh Sampson of the Jaffe Food Allergy Institute at Mount Sinai College of Medicine. "I think this study suggests that food additives may have an effect on child behavior and certainly supports the need for further study."