Almost every parent has a story about their kid bouncing off the walls after downing a package of jelly beans or eating a neon blue-frosted cupcake at school. Most blame the sugar.
But some new research suggests that the rainbow of artificial colors may have a bigger effect on children's behavior. And in other parts of the world, some organizations are starting to take action on these ingredients.
Earlier this year, the UK's Food Standards Agency, the British regulatory counterpart to our Food and Drug Administration, asked food makers to voluntarily recall six artificial colors in food by 2009, a step many food companies have completed.
And in July, the European Parliament voted to add warning labels with the phrase "may have an adverse effect on activity and attention in children" to products with the same six synthetic red and yellow dyes, prompting many large food makers such as Nestle to reformulate their products rather than risk a drop-off in sales.
These actions were spurred by a study published in September 2007 in the medical journal the Lancet supporting what some parents and scientists had suspected for decades -- that food dyes are linked to hyperactivity, even in kids who don't normally exhibit this behavior.
"The position in relation to artificial food colors is analogous to the state of knowledge about lead and IQ that was being evaluated in the early 1980s," says the study's lead author, Jim Stevenson, psychology professor at the University of Southampton, in a March letter to the UK Food Standards Agency, urging action.
But many psychologists and food scientists aren't convinced.
"I think the studies are intriguing," says Roger Clemens, a food scientist and USC professor of pharmacology. "But the clinical data are still wanting."
"I haven't seen any science that tells me I really need to be warning parents against these," says Scott Benson, a Pensacola, Fla.-based child psychologist who treats hyperactive children in his practice.
The FDA still considers the nine synthetic colors allowed in food -- in grocery stores and restaurants-- as safe as long as each production batch has been certified to meet composition standards.
On its website, the agency points to a consensus report by the National Institutes of Health in 1982 that, the FDA says, concluded there was no "scientific evidence to support the claim that food dyes cause hyperactivity."
But watchdog groups and some scientists say that reference by the FDA is misleading. That same panel, says the Washington, D.C.-based advocacy group Center for Science in the Public Interest, also acknowledged that some children already diagnosed as hyperactive and on a restricted diet experienced an increase in hyperactivity when given moderate doses of artificial food dyes and did not experience similar increases after receiving a placebo.
Now the FDA is reviewing a petition submitted in June by the Center for Science in the Public Interest for a ban on eight artificial food colors certified for use in processed food; Blue 1, Blue 2, Green 3, Red 3, Red 40, Orange B, Yellow 6 and Yellow 5 (tartrazine), a color the FDA concluded in 1986 is a known allergen to a small group of people, causing itching and hives. (A ninth color, Citrus Red 2, is used only on the skin of oranges to make them more appealing and is not included in the center's petition.)
The center is also asking the FDA to require warning notices on the labels of foods that contain the dyes -- which are already listed on ingredient labels until the ban is in place and to require neurotoxicity tests for new food dyes and additives.
"The safety testing on these [dyes] was done 30 to 50 years ago," says the center's executive director Michael Jacobson. "I suspect the tests are out of date and we have higher standards now that would show positive evidence of harm."
Suspicion about the effect of food dyes on behavior swelled in the mid-1970s after San Francisco allergist Dr. Ben Feingold published his book "Why Your Child Is Hyperactive," detailing his research on the behavioral benefits of eliminating food dyes and additives -- guidelines that became known as the Feingold diet.
But a string of studies with poor methodology failed to prove a conclusive link in the years following, and the issue, researchers say, dropped off most people's radar.
In the last decade, however, scientists have taken up the topic again with some intriguing results.
In 2004, New York psychiatrist Dr. David Schab conducted an analysis of 15 studies on dyes and hyperactivity that he considered to be the most rigorous available.
He concluded that artificial dyes promote increased hyperactive behavior in children who had already been diagnosed as hyperactive.
And two other studies linked artificial dyes to hyperactivity in children who were not already diagnosed with hyperactivity.
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.
"We're now seeing small effects [from dyes] but they haven't been dramatic effects," he says, "and they don't explain most of the problematic behavior."
Meskin also says that the studies so far haven't been precise enough to pinpoint which artificial colors may have problems. It's unlikely, he says, that all of them would have the same effect on the brain since they are chemically different and derived from different ingredients -- some from petrochemicals and others from coal tar.
New York psychiatrist Schab says the study was the most damning yet in linking artificial food colors to hyperactivity. The degree of observed differences in behavior by eliminating the dyes and preservative, he says, could be enough to lead some parents not to seek medication such as Ritalin for their child.
Headlines about these studies prompted Janice Markham, a Los Angeles-based writer and mother of two, to change her shopping habits.
"Anything I can get without dyes I will," she says. "I look at the packaging on everything."
Markham and other parents are willing to pay a premium for products that are natural. But to date, most large food makers have not reformulated their products.
"We have not seen any clear-cut scientific substantiation of these claims [of hyperactivity]," says Kris Charles, a Kellogg Co. spokeswoman. "At this point, we aren't planning any new U.S. product launches with only natural food colorings." But, Charles says, the company will "continue to monitor consumer preferences and comply with regulations."
Some food makers such as Kraft are putting out separate Back to Nature lines with no food dyes or preservatives.
But Jacobson says generally, if anything, U.S. manufacturers are putting more synthetic dyes than ever in their products geared to kids, such as Kraft's Lunchables line and Pepperidge Farm's Goldfish crackers in a rainbow of colors.
He can't say for sure if kids are consuming more, however, because consumption figures are not measured. But, he says, the amount of synthetic dyes certified by the FDA for use in food between 1955 and 2007 climbed fivefold, from 12 milligrams per capita per day in 1955 to 59 milligrams per capita per day last year.
Given those amounts, the Center for Science in the Public Interest claims, the amounts of dye being used in the studies are probably less than what most children are consuming.
Food manufacturers, for their part, say they use these colors to make foods more appealing to consumers. Yellow food coloring makes waffles look more evenly golden brown. Red or orange dye makes juice look sweeter.
However, food scientists say all of this can be achieved without using artificial colors.
Food makers "have the ability to do it, but they don't want to put any effort into it," says Pete Maletto, a New Jersey-based food industry consultant and food scientist, who has helped companies such as ConAgra reformulate their products with natural colors from plant sources such as beets or turmeric.
Some U.S. companies, he says, have experimented with replacing artificial colors in certain products, but ultimately changed their minds when they knew they would have to charge more.
"It is more expensive. You have to use more (natural pigment) so it costs a little more," Maletto says. "But if you say 'no artificial colors' on the box, you could charge a customer 10 cents more and they would pay it," he adds.
Maletto and other scientists say the majority of food makers won't act unless the FDA moves to ban the colors, or they are required to put a warning label on the package.
"It will be the same as what's happened with trans fats," Maletto said. "Only then will they do it."