Schab DW, Trinh NH. (2004) Journal of Developmental & Behavioral Pediatrics. 25(6) 423-434
Burgeoning estimates of the prevalence of childhood attention-deficit/hyperactivity disorder (ADHD) raise the possibility of a widespread risk factor. We seek to assess whether artificial food colorings (AFCs) contribute to the behavioral symptomatology of hyperactive syndromes.
We searched ten electronic databases for double-blind placebo-controlled trials evaluating the effects of AFCs. Fifteen trials met the primary inclusion criteria. Meta-analytic modeling determined the overall effect size of AFCs on hyperactivity to be 0.283 (95% CI, 0.079 to 0.488), falling to 0.210 (95% CI, 0.007 to 0.414) when the smallest and lowest quality trials were excluded. Trials screening for responsiveness before enrollment demonstrated the greatest effects.
Despite indications of publication bias and other limitations, this study is consistent with accumulating evidence that neurobehavioral toxicity may characterize a variety of widely distributed chemicals. Improvement in the identification of responders is required before strong clinical recommendations can be made.
This systematic review of the evidence from 15 previously published randomised controlled trials found that artificial food colourings (AFC) do worsen the behaviour of children selected for hyperactivity - i.e. ADHD-type behaviour problems.
Similar negative effects of artificial food colourings on behaviour have also recently been reported from children from a general population, in the largest randomised controlled trial on this issue to date (involving 277 3-year-olds from the Isle of Wight in the UK).
Those researchers tested 6 AFCs along with one common preservative for their effects on the children's behaviour. Furthermore, the UK children were carefully screened and selected with respect to both ADHD and allergies, to ensure balanced numbers of children who had one, both, or neither of these conditions.
This large Isle of Wight study showed detrimental effects of the food additives versus placebo across the sample as a whole, i.e. these were not specific to any of the subgroups.
Unfortunately, this recent UK study was published too late to be included in the systematic review from the US reported here. It did, however, lead to calls for a ban on these kinds of artificial additives: see BBC News online, 25 May 2004
Given that these AFCs have no nutritional value (and are often used to make non-nutritious foods appealing to children), the evidence of potential risks now emerging from well-conducted studies would seem to support such calls. In the UK, however, the FSA has called for more research before considering any change in official regulations.
Meanwhile, parents and carers wishing to prevent their children from consuming artificial additives of this kind will not find it easy. However, a list of children's foods that contain these additives can be found on the website of the Food Commission