Food Coloring and ADHD - No Link, But Wider Safety Concerns

By Andrea Chronis-Tuscano
University of Maryland Clinical Psychologist

The debate over whether artificial food coloring contributes to childhood ADHD - Attention Deficit Hyperactivity Disorder - has itself been colored for decades by weak science and strong emotional beliefs. As one of the scientists who testified before a Food and Drug Administration (FDA) panel on the issue last March, I had no qualms in debunking the alleged connection between these food additives and ADHD. Yet, the testimony from other experts at the panel convinces me that we need more conclusive research on their overall safety. All parents should think twice before exposing their children to these substances. But parents of children with ADHD should not be misled into thinking that artificial dyes are the cause of the condition.

As a University of Maryland clinical psychologist specializing in the assessment and treatment of this disorder, I told the FDA panel unequivocally that NO convincing evidence supports the idea that food color additives cause ADHD or that strict elimination diets effectively treat the condition. I stand by this assessment.

Currently, the best science indicates that ADHD is a brain-based disorder largely attributable to a person's genetic makeup. But environmental factors play a role as well, and it's conceivable that food additives could be one such trigger. My concern as a clinician is that the belief held by many parents that these diets cure ADHD often delays or prevents them from getting the treatments backed by strong scientific evidence - behavior therapy, stimulant medication or their combination.

The earlier parents seek evidence-based treatment, the better. Intensive, multi-modal treatment is crucial for the success of these children. Going down the wrong path wastes resources and, most critically, precious time in the life of a child.

SCIENTIFIC EVIDENCE

The research conducted on food dyes and hyperactivity, beginning in the 1970s, was abysmal at best. These studies were driven by the popularity of the "Feingold Diet," which eliminated additives from children's diets. These studies were plagued by small sample sizes, inclusion of children based on their reported sensitivity to food dyes, and a lack of unbiased assessments of the children's behavior. Parents who believed in these diets reported improved behavior when their children followed the regimen - not exactly convincing science.

More recently, researchers at the University of Southampton conducted better designed studies on the effects of food additives - both coloring agents and preservatives - using a general, representative sample of children. These were double-blind studies, so participants didn't know whether children were getting additives or a placebo. The researchers used multiple measures of behavior, including parent and teacher ratings, direct observations of the children in the classroom and cognitive tests assessing attention and impulsivity. These studies did detect quite small, but statistically significant, effects from the mixtures which included both color additives and a preservative, sodium benzoate.

A subsequent analysis conducted by this group found that a gene involved in the regulation of histamine predicted which children responded. Unfortunately, it's unclear from this study whether the colors, preservatives, or the combination of the two were responsible for the behavioral effects. Furthermore, if the effects were due to the coloring, the study can't tell us which specific agents were responsible, nor what dosages produced effects. These results may be intriguing, but are scientifically inconclusive. Based on this evidence, we simply cannot say that food color additives cause or contribute to ADHD.

Given the lack of hard evidence, I am not convinced that food coloring additives are dangerous, but I am also not convinced they are not. It is certainly possible that some small subset of children have a unique sensitivity to these substances. The issue shouldn't end here. We need better answers about the effects of these additives on our nation's children.

NEXT STEPS

I learned several things through my participation in the FDA hearing which concern me both as a scientist and parent of two young children.

• Food coloring is overrepresented in products designed to be attractive to children;
• FDA has no specific data on food coloring consumption for particular subgroups in the U.S., including children;
• Committee experts pointed out that appropriate toxicology studies have not been conducted to determine the effects of these additives on developing brains at different ages.

Beginning in the womb, developing brains are particularly sensitive to toxins. It's important to get better information about how much of these substances American children consume, and whether these levels are dangerous.

Despite the limited science, the UK and other European nations have required manufacturers to include warning labels - a step that may discourage the use of these additives in foods, especially those intended for children. After all, these dyes are purely aesthetic and can be replaced by natural coloring.

Meanwhile, even if the evidence does not currently warrant FDA action, parents and consumers can still act. Although I have no plans to put my family on any type of elimination diet, since my experience on the panel, I've become more attuned to food labels. Interestingly, more than 90 percent of the food coloring I found in my own pantry was in my children's vitamins, medication, and toothpaste.

But that's a stopgap. Buying natural foods without additives costs more and is less convenient; it's simply not feasible for all Americans. A more comprehensive scientific answer to the effects of food coloring additives on U.S. children is needed. Keep this issue on the nation's public health agenda.

Andrea Chronis-Tuscano is an Associate Professor of Psychology at the University of Maryland and directsthe Maryland ADHD Program.