The first of these two studies was published in 2003 in the journal Archives of Disease in Childhood. Conducted at the University of Southampton, it involved 277 3-year-old children who were given a diet free of artificial colorings and benzoate preservatives for one week.
During the next three weeks, the children received either drinks containing artificial yellow and red colorings and soda preservative sodium benzoate, or a placebo mixture. The scientists and the parents did not know which children received the artificial colors and preservative and which did not.
The results showed consistent, significant improvements in hyperactive behavior during the period when the diet did not contain benzoate preservatives and artificial colorings, as measured by parents' observations.
Parents reported worsening behavior in their children during the weeks when these ingredients were reintroduced.
On the basis of this and other studies, schools in Wales in 2004 mandated the withdrawal of foods containing these colors from school lunches.
The UK Food Standards Agency then commissioned a second study from the University of Southampton that made headlines on both sides of the pond when it was published last fall.
In that study, 153 3-year-olds and 144 8- and 9-year-olds were given drinks containing one of two different mixes of four artificial colors -- the same ones tested before and Red 40 and Quinoline Yellow -- and preservative sodium benzoate, or a placebo.
The older children showed a "significantly adverse effect" from both dye mixes, as measured by a parent rating of a list of behaviors including concentration, fidgeting, restless or "always on the go" behavior, interrupting conversations or talking too much and fiddling with objects or their own body.
The adverse reaction of the 3-year-olds using this behavior scale was rated significant for only one of the dye/preservative cocktails.
Based on that study, the UK Food Standards Agency asked manufacturers to pull the synthetic colors involved in the study.
So Kellogg's strawberry Nutri-Grain Cereal Bars that are sold in Britain now contain beetroot red, annatto and paprika extract, while those sold in the U.S. are tinted with Red 40, Yellow 6 and Blue 1.
Mark Meskin, a professor of human nutrition at Cal Poly Pomona, who also serves as a spokesman for the food industry trade group Institute of Food Technologists, says he doesn't think a wholesale ban on synthetic dyes is necessary, given the modest difference in behavior noted for most kids in the study.
