Data Analysis Questions Food Coloring Link to ADHD

A meta-analysis of recent scientific literature has questioned data alleging a link between synthetic food colors approved by the Food and Drug Administration (FDA) and attention-deficit/hyperactivity disorder (ADHD). Joel Nigg, et al., “Meta-Analysis of Attention Deficit/Hyperactivity Disorder or Attention Deficit/Hyperactivity Disorder Symptoms, Restriction Diet, and Synthetic Food Color Additives,” Journal of the American Academy of Child & Adolescent Psychiatry, January 2012. Researchers evidently assessed 24 articles on synthetic food colors and 10 additional studies on dietary restriction, but ultimately found that several effects observed for food color additives were subject to publication bias or other flaws.

In particular, the study authors noted that, while a restriction diet appears “to
benefit some children with ADHD,” reports based on information from parents
or teachers/observers were not wholly reliable or consistent even “after
quality of measure was taken into account.” The analysis also revealed that
“nearly all studies examined combinations of colors, with too little consistency
in their mixtures for us to test comparative effect sizes of different mixtures
or individual compounds.” The have thus recommended further efforts to
“quantify comparative effects of individual colors and additives or competing
specific mixtures,” as well as additional research restricted to FDA-approved
food colors only.

“These gaps reflect a complete absence of modern studies on this topic in
the United States since the early 1990s. The literature remains limited by lack
of validation of blinding in many studies, and wide variety in methodology
which would be best addressed by a pooled analysis of individual data across
studies—not possible with the old literature,” concluded the authors. “In short,
despite 35 years of research and evidence of an effect of food colors on objective
measures of attention, the database that would confirm this possibility
and generalize it for contemporary use is woefully out of date with regard to
policy or clinical decisions in the United States.” See FoodProductDesign.com,
March 2, 2012.