Systematic review on attention deficit hyperactivity disorder (ADHD) and food additives in children

Abstract

Attention-deficit hyperactivity disorder (ADHD) is a developmental disorder of inattention, impulsivity and hyperactivity. It is the most commonly diagnosed psychosocial problems in childhood with continuing impact into adulthood. This systematic review aims to identify the role of food additives, specifically artificial food coloring, in ADHD and its symptoms. PubMed, Sciencdirect, Cochrane Library and Google Scholar databases (1991-April 2012) were searched, which was supplemented by manual searches of the reference lists. Seven randomized or quasicontrolled trials of elimination diet were summarized. Six of these studies showed artificial food coloring was positively associated with ADHD and its symptoms. This review provides some evidence that artificial food coloring plays a role in ADHD and its symptoms. However, the studies reviewed only showed behavioral improvement after eliminating certain type of artificial food coloring, which does not imply artificial food colorings cause ADHD. Additionally, small sample size, inconsistent definition of artificial food colouring, subjectively reported ADHD using various assessment tools, and possibly publication bias limit the generalizability of the findings. If causal, reducing the intake of artificial food coloring could provide an alternative treatment of ADHD in the future. Understanding the mechanism underlying the association may provide insights into the developmental origins of ADHD.