Link between food dyes, childhood hyperactivity gets renewed attention
When it comes to the safety of dyeing food, the one true shade is gray.
Artificial colorings have been around for decades, and for just about as long, people have questioned whether tinted food is a good idea. In the 1800s, when merchants colored their products with outright poisons, critics had a pretty good case. Today’s safety questions, though, aren’t nearly so black and white — and neither are the answers.
Take the conclusions reached by a recent government inquiry: Depending on your point of view, an official food advisory panel either affirmed that food dyes were safe, questioned whether they were safe enough or offered a conclusion that somehow merged the two. It was a glass of cherry Kool-Aid half full or half empty.
About the only thing all sides agree on is that there would be no discussion if shoppers didn’t feast with their eyes. Left alone, margarine would be colorless, cola wouldn’t be dark, peas and pickles might not be so vibrantly green, and kids cereals would rarely end up with the neon hues of candy. But as the 1990s flop of Crystal Pepsi showed, consumers expect their food to look a certain way.
Some of the earliest attempts to dye food used substances such as chalk or copper — or lead, once a favorite for candy — that turned out to be clearly harmful. Most of the added colors in use today were originally extracted from coal tar but now are mostly derived from petroleum.
Overseeing the safety of artificial food color was one of the reasons the U.S. Food and Drug Administration was founded (with its current name, in 1930). And the issue of food dye safety has continued to attract government notice, sometimes in dramatic ways, such as the time investigators demanded to know why trick-or-treaters became ill in 1950 after eating Halloween candy dyed with orange No. 1.
The most recent government attention came in March, when an FDA advisory panel made up of scientists, consumers and industry representatives held a two-day hearing to try to determine whether food dyes cause hyperactivity in children. It is a debate that has gone on, in some incarnation, more than 30 years. Though scientific attention has grown, the disagreement lingers, partly because the issue is complicated to study and partly because dyes, if harmful, probably affect only a subset of children who have some yet-undiscovered genetic sensitivity. Over the years, skeptics of any connection have seized on uncertainties and other logistical flaws in the research that could lead to misleading results.
Still, many scientists say studies are strong enough to warrant some kind of government action. And some of them are now criticizing the FDA, saying that, in retrospect, questions about the hyperactivity-dye link were presented to the advisory panel in a way that meant inaction was almost a foregone conclusion.
“To me, the whole process was defective,” says Bernard Weiss, a psychologist in the Department of Environmental Medicine at the University of Rochester School of Medicine and Dentistry in New York who was invited to speak before the panel. The main question that committee members were assigned was whether “a causal relationship between consumption of certified color additives in food and hyperactivity in children in the general population has not been established” (a conclusion ultimately supported by 11 of 14 voting panel members).
Weiss calls that “a ridiculous question,” not only because of its tortured, negative wording, but also because even those concerned about food dyes acknowledge that the science has not shown a link to hyperactivity in all kids.
Nine different artificial dyes are currently approved for use in the United States; many of these chemicals have been staples of the food industry for generations. While the FDA does not have data on consumption, it does keep track of how much dye of each type gets the OK for use in products; the amount per capita has increased fivefold since the 1950s. Dyes have never been without criticism — a “pure food” movement was well under way even by the late 1800s. But specific concern about hyperactivity and other neurological effects first arose in 1975, when Ben Feingold, former chief allergist at Kaiser Permanente Medical Center in San Francisco, hypothesized that food additives were contributing to hyperactivity. His book Why Your Child is Hyperactive drew largely on his own clinical observations.
In 1976 in the journal Pediatrics, researchers published a study that compared a regular diet with a diet that eliminated artificial flavors and colors in 15 hyperactive children. After eating what has since become known as the “Kaiser Permanente elimination diet” or the “Feingold diet,” children showed an improvement in symptoms such as difficulty paying attention.
Three decades of studies since then have accumulated evidence linking food dyes to an exacerbation of hyperactivity. But the controversy remains unsettled. Skeptics have a lot of ammunition, pointing out that findings often have been inconsistent and confusing. To set up a study of food dyes, researchers have to juggle a lot of variables at once — including how big a dose of dyes to give, which ones to give and the fine art of having parents and teachers document symptoms that aren’t easy to measure.
Other factors also complicate the research. Studies have used mixtures of dyes, making it difficult to tease out the possible effects of any individual color. Also, it may be that only an unknown subset of children are affected: In a scientific analysis, the children not affected might outnumber those who are, blunting the overall findings when data are lumped together.
Finally, evidence suggests that dyes may not be the lone culprit. Children who appear to be sensitive to dyes may also have neurological reactions to other ingredients, even naturally occurring components such as wheat and chocolate. In some studies, children were given the dyes in cookies; if the children react to wheat or milk as well, the “placebo” might not have been the placebo scientists thought.
In the end, the disagreement comes down to this: How much evidence is necessary to add product warnings about (or ban, as some consumer groups want) chemicals that offer no nutritional benefit and are consumed each day by millions of healthy children?
Europe gets the blues
Food safety advocates believe the substantial suggestion of harm, even without proof, is enough to take action. So does the European Parliament, which in 2008 dictated that foods with certain dyes had to contain warnings that the chemicals “may have an adverse effect on activity and attention in children.” Neither the FDA nor American lawmakers have gone that far, saying that the levels of dye currently in foods are safe.
Most dyes have no set cap on the amount that can be used, just stipulations requiring manufacturers to use only enough to reach their desired color, and no more. “When the FDA established legal limits on dyes, they did not consider children,” says Laura Anderko, a researcher in public health at Georgetown University Medical Center in Washington, D.C. And it is not known, she says, what the lasting effects from constant exposure might be. “Kids, they have a long shelf life. If they are exposed at an early age — depending on those kinds of petrochemicals that are consumed — it could mean lifelong impacts,” she says.
The color industry says any link between food coloring and hyperactivity remains unproven. “We don’t see any strong compelling data at this point that there is a neurological effect,” says Sean Taylor, a chemist at Verto Solutions in Washington, D.C., and a representative of the International Association of Color Manufacturers. He notes that the dyes on the market today have been consumed in populations worldwide, without any apparent harm, for decades. In animal toxicity tests, Taylor says, most of the dyes in food are excreted, and the small amounts absorbed are broken down by the liver.
More than a dozen clinical studies have tried to investigate the relationship between food dyes and hyperactivity. In 2004, psychiatrists David Schwab from Columbia University and Nhi-Ha Trinh of Harvard University published a meta-analysis of all 15 known double-blind placebo-controlled trials — meaning those in which neither the researchers nor the participants knew who was getting the dyes. That study, in the Journal of Developmental & Behavioral Pediatrics, reported that the results “strongly suggest an association” between food dyes and hyperactivity, though the researchers included a long list of caveats.
Following the 2004 meta-analysis, the British Food Standards Agency (the equivalent of the U.S. FDA) commissioned large studies to further examine whether food dyes, along with a common food preservative, affected children’s behavior. Unlike most previous investigations, these new experiments included children from the general population who had no history of hyperactivity.
In those studies, researchers from the University of Southampton gave two groups of children (one toddler group, and one school age) beverages with one of two mixes of food dyes and the preservative sodium benzoate or a placebo, and asked parents and educators to note any behavior changes. The older children also took a computerized test designed to measure attention.
The results, published in 2007 in the Lancet, “lend strong support for the case that food additives exacerbate hyperactive behaviors,” the researchers write. “Our results are consistent with those from previous studies and extend the findings to show significant effects in the general population.” The scientists recognized the potential political impact of their findings: “The implications of these results for the regulation of food additive use could be substantial.”
And in Europe, they were. While the European Food Safety Authority did not think the evidence was strong enough to prompt action, the European Parliament was convinced. Dyes are not banned outright, but warning labels alone have been enough to change the way many products are made. A strawberry sundae at McDonald’s in the United States gets a boost of crimson from red No. 40. In Great Britain, a McDonald’s strawberry sundae gets its red only from strawberries.
In 2008, the year warning labels took effect in Europe, the D.C.-based Center for Science in the Public Interest (the same food watchdogs known to denounce the nutritional wasteland of convenience foods and movie popcorn) petitioned the FDA to ban the dyes. A long list of scientists and researchers signed on to the center’s appeal. “Food manufacturers voluntarily could substitute safe natural colors or other ingredients (such as fruit or fruit juices) for dyes, but that’s unlikely to happen throughout the food supply without the level playing field provided by government regulation,” the document stated. “Accordingly, the Food and Drug Administration ... should ban the use of dyes in all foods; until such action takes effect, the FDA should require a prominent warning notice on product labels.”
While no large trials have been published since 2007, the government took the Center for Science in the Public Interest petition seriously enough to hold the hearings in March, asking members of its Food Advisory Committee to decide whether the evidence establishes a link between food dyes and hyperactivity in children in the general population.
Even Michael Jacobson, executive director of the Center for Science in the Public Interest, says he would answer “no.” To him and others, it was not the valid question to address. Better, he said, would have been to assess whether food dyes pose a danger to certain children, in the same way that allergens affect only susceptible people. Few products, no matter how dangerous, affect everyone in the population. “Even smoking does not affect everybody,” he says.
Metabolic black box
No one knows which children may be at risk, because the biology behind any potential neurological effect associated with hyperactivity isn’t clear. Taylor, the color industry biochemist, says that animal studies find that the molecules do not easily get through intestinal cell walls, and most of the dye passes through the body without leaving the digestive system.
Laura Stevens, a nutrition researcher at Purdue University in Indiana, acknowledges that this is the case. “In animals, very little of it is absorbed,” she says. “It is excreted in the feces.” But that doesn’t necessarily negate the idea of any effects on the body, she says; effects could come through metabolites, or through indirect mechanisms.
As examples, she cites two studies by British researchers. In one, published in the Journal of Nutritional Medicine in 1990, the scientists investigated how the yellow dye tartrazine affected the zinc levels of 10 hyperactive boys, compared with 10 nonhyperactive peers. (Zinc is a mineral important for proper brain function.) The team found that zinc levels dropped in the blood and increased in the urine among the hyperactive kids after tartrazine consumption. Another study, published in the Journal of Nutritional and Environmental Medicine in 1997, found a similar drop in zinc levels, and an increase in hyperactivity, in some children consuming tartrazine.
Newer research suggests that dyes trigger the release of histamines, which are part of the body’s immune system. An experiment reported last year in the American Journal of Psychiatry suggested that differences in genes that control histamines might explain why some children are affected and others are not.
But studies are few. In truth, Stevens says, aside from extrapolations from animal studies, the metabolic fate of dyes in humans is a black box. She and her colleagues at Purdue are among those trying to look at food dye metabolism in humans. “If there’s any chance at all there’s a problem, this should be addressed,” she says.
Ultimately, the future of food dyes may not rest with scientists or government regulators, but with consumers, says Ron Wrolstad, an agricultural chemist at Oregon State University in Corvallis.
“A lot of times now, particularly with natural colorants, it will be a marketing decision rather than a regulatory ruling,” he says. The snack food giant Frito-Lay, for instance, has announced, and heavily publicized, a commitment to use fewer artificial dyes in its products. A company spokeswoman said in December that the move was in response to consumers wanting more snacks “made with real food ingredients.”
“My personal opinion is that the synthetics don’t cause you any harm, but I don’t think they do you any good,” Wrolstad says. While other researchers are looking for harmful effects of synthetic dyes, Wrolstad is looking for beneficial effects of natural, plant-derived colors. “A lot of these compounds have antioxidant properties,” he says.
Though just as the idea of harm by synthetic colors isn’t universally accepted, neither is the suggestion of benefit from dyes extracted from plants. “I would feel a lot more comfortable if we had some data on those, too,” Weiss says.
In the meantime, dyes of all kinds will continue to dominate the grocery aisle unless shoppers demand otherwise. In the food business, the most influential color is green.
In the limelight
Though concern over a link to hyperactivity has prompted the latest attacks on food dyes, artificial colorings have caught the public’s attention for other economic and health reasons for more than a century.
1850s A Victorian-era domestic standby Enquire Within Upon Everything described how bread could be tested at home for the presence of alum, a metallic salt used to create a more preferable, whiter color in the dietary staple. As early as the Middle Ages, some bread manufacturers were rumored to make very white bread on the cheap by adding chalk.
1890s One effort used by the dairy industry to prevent newly invented and relatively cheap margarine from undercutting the popularity of butter was the push for regulations that would tax or ban margarine with the yellow tint of butter. (Naturally, margarine is colorless.) Anticoloring laws were adopted in 30 states, and some legislatures went so far as to demand that margarine be dyed pink. Because of the restrictions, some margarine manufacturers sold yellow dye packets with their products, so consumers could color their own margarine at home.
1950s In 1950, children became ill after eating Halloween candy containing orange No. 1, which had been approved for use in food by the U.S. Food and Drug Administration. The reports led to a public outcry, and along with other concerns, led the FDA to re-evaluate the safety of food colorings. Several dyes were delisted, and the Color Additive Amendments of 1960 established the current regulatory protocol.
1970s In the 1970s, it was red No. 2’s turn to cause a stir. Russian studies had suggested that the dye caused rats to develop intestinal tumors and was toxic to the gonads and embryos. Though the tests were largely debunked, when combined with earlier studies showing breast tumors in female rats fed the dye, the findings were enough to lead to a public health scare. The FDA banned red No. 2, and many manufacturers removed red products regardless of whether they contained the dye. Mars didn’t bring back red M&Ms until the late ’80s.
1990s Natural food dyes have caused controversy too. The reddish cochineal extract and carmine came to the attention of the Center for Science in the Public Interest in 1998. The dyes, made from a type of female beetle, had been used for hundreds of years, exempt from certification because they are natural. Recorded allergic reactions as well as anecdotal reports of outrage among vegetarians and kosher-keeping Jewish people who were unknowingly consuming insect products prompted demands for labeling. The FDA agreed to require manufacturers to list the dyes as ingredients on the product label, but consumers have to figure out for themselves that the products come from animals.
The U.S. Food and Drug Administration currently certifies nine synthetically produced food dyes (three popular colorings are described below). Such dyes can transform colorless products, giving faded veggies a more vibrant hue and making children’s candies more fun.
Brilliant blue Designated as blue No. 1 by the FDA, this dye is found in ice creams, ice pops, baked goods and a host of blue raspberry–flavored beverages. It shows up in ranch-flavored chips, prepared guacamole and mixed-berry applesauce. The dye was approved by the FDA in 1969.
Allura red Red No. 40 is found in strawberry-flavored drinks, ice creams and cream cheeses; some Nutri-Grain bars; licorice; and most other red sweets. It was approved by the FDA in 1971 and, in terms of consumption, is currently the most-used food dye.
Tartrazine Yellow No. 5 is in products such as Mountain Dew, Peeps, Doritos and Cheez Doodles. It’s commonly found in relish, pickles, lemon-flavored seasonings and boxed macaroni and cheese. The dye was approved by the FDA in 1969.
For a transcript of the food dye hearing, visit [Go to]
D. McCann et al. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: A randomised, double-blinded, placebo-controlled trial. Lancet, 2007, Vol. 370, p. 1560. Abstract available: [Go to]
D.W. Schab and N.T. Trinh. Do artificial food colors promote hyperactivity in children with hyperactive syndromes? A meta-analysis of double-blind placebo-controlled trials. Journal of Developmental and Behavioral Pediatrics, Vol. 25, 2004, p. 423. Abstract available: [Go to]
Stevens, L.J, et al. 2010. Dietary sensitivities and ADHD symptoms: Thirty-five years of research. Clinical Pediatrics, Vol. 50, 2010, p. 279. Abstract available: [Go to]
Food Dyes: A Rainbow of Risks. Available at [Go to]