ADHD and Food Dyes
The effects of artificial food dyes on hyperactivity have been studied since the early 1970s. Evidence from this scientific research throughout this period has been conflicting, but more recent reviews of the research support the idea that eliminating artificial food coloring from the diet may have a beneficial effect on the symptoms of ADHD and may provide additional benefit beyond treatment with medication alone.
Furthermore, research suggests that artificial food colorings may have an effect of increasing hyperactivity in all children, with or without a diagnosis of ADHD. A study from the United Kingdom published in 2007 showed a small but significant increase in hyperactivity in children who consumed food dyes, leading the European public health officials to ask food manufacturers to remove the dyes or place a warning on the label stating that artificial food dye "may have an adverse effect on activity and attention in children."
These European policy changes led the U.S. Food and Drug Administration (FDA) Food Advisory Committee to conduct a review of the evidence on artificial food colorings and ADHD in 2011. However, after much debate, the committee voted 8 to 6 to not require any new restrictions or labeling changes for food colorings without further evidence of harm caused by artificial food colorings. Research continues, and further reviews of research conducted since 2011 may prompt the FDA to revisit this policy in the future.
Although the proposed reasons for the effects of food coloring on behavior remain unclear, one of the most common ideas relates to food allergies or "hypersensitivities." This idea was originally presented by Dr. Benjamin Feingold, an allergist and pediatrician, in the early 1970s. His work resulted in the development of the Feingold Diet, which eliminates food dyes, as well as other food additives, from the diet as a method to treat behavioral problems.
More recent evidence suggests that artificial food colorings might actually have other effects that contribute to hyperactivity in children. Some studies show that food dyes alter levels of zinc and other nutrients important in brain functioning. In most studies, the increased hyperactivity and inattention observed after consuming artificial food colorings varied widely, with some children seeing a large effect and others experiencing no changes at all.
More research is needed to determine what the actual cause might be and why some people are more susceptible to the effects of food dyes than others.