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Chronic and acute effects of artificial colourings and preservatives on children’s behaviour
Project Code: T07040;
- Stephenson, J., Sonuga-Barke, E., McCann D., Grimshaw, K., Parker, K.M., Rose-Zerilli, M.J., Holloway, J.W. and Warner, J.O. (2010) American Journal of Psychiatry 167 1108-1115. DOI: 10.1176/appi.ajp.21010.09101529
School of Psychology, University of Southampton
Stevenson, J ;
Allergy and Inflammation Sciences, University of Southampton.
School of Psychology, University of Southampton
This Technical Report is structured such that the main text provides an integrative overview of the results of the studies on 3 year old and on 8 to 9 year old children. Annexes 1 and 2 contain the detailed accounts of the design, sampling, measurement and data analytic methods and findings for the study of 3 year old and 8/9 year olds respectively.
There is a longstanding suggestion that artificial food colours and other food additives such as preservatives (AFCA) influence behaviour in children. It is over 30 years since Feingold made his initial claims of the detrimental effect of AFCA on children’s behaviour. 1 The main putative effect of AFCA is to produce overactive, impulsive and inattentive behaviour, i.e. hyperactivity, which is a pattern of behaviour that shows substantial individual differences in the general population. Children who show this behaviour pattern to a marked degree are likely to be diagnosed with attention deficit hyperactivity disorder (ADHD).2 Despite the failure of early studies to identify the range of proposed adverse affects,3 a more recent meta-analysis of double-blind, placebocontrolled trials has shown a significant effect of AFCA on the behaviour of children with ADHD.4 The possible benefit in reducing the level of hyperactivity of the general population by the removal of AFCA from the diet is less well established. There is some evidence from our earlier study on the Isle of Wight of adverse effects on hyperactivity measured by parental ratings for 3 year old children of one mix of additives.5 These findings required replication on three year old children and to establish if the effects could be found using a wider range of measures of hyperactivity. The present community based double-blinded, placebo-controlled food challenge (DBPCFC) was designed to extend the age range studied to include 8/9 year old children to determine if the effects could also be detected in middle childhood.
The material in this technical report has been incorporated into one paper that has been published in the Lancet.6 The evidence we have obtained is that certain mixtures of artificial colours and sodium benzoate preservative (referred to in this report as Mix A and Mix B) adversely affect the hyperactive behaviour of children in some age groups compared with a placebo.
The results replicate and extend the findings from our earlier study.5 The specific findings were that with Mix A there was a significant (p < 0.05) adverse effect on the average hyperactive behaviour of 3 year old children as measured using the chosen outcome measure of a Global Hyperactivity Aggregate (GHA) and based on the primary analysis of the study (the whole cohort). In contrast, Mix B was without significant effect on the behaviour of 3 year old children. The reverse picture was seen with 8/9 year old children. In this case, compared with placebo, Mix B had a significant adverse effect on the behaviour of children (p<.05). However, for the whole cohort Mix A was without significant effect on the behaviour of 8/9 year old children. While an aggregate score (GHA) was the primary outcome measure for this study it is noted that, as in the previous Istudy carried out on the Isle of Wight, that the parental ratings of behaviour are a significant contributor to the GHA score.
The importance of these findings is that they confirm that the adverse effect of certain artificial food colours that has been implicated in children with hyperactive syndromes4 can also be demonstrated in two samples taken from the general population.
For both 3 and 8-9 year olds a range of factors were examined to determine if they made the child more vulnerable to the effects of the food colour and benzoate preservative mixes. None of the social factors examined (age, gender, pre-trial diet, maternal education) moderated the effects of the active mixes at either age. However, for the 3 year old children consuming more than 85% of the drink challenges a polymorphisms in the histamine Nmethyltransferase gene (HNMT Thr105Ile) moderated the effect on the GHA of Mix A compared to Placebo. Specifically the absence of HNMT 105Ile in the genotype made the 3 year-old children more vulnerable to the adverse effects of the Mix A additive mixture. For the 8 to 9 year old children only, this same moderating effect of the absence of HNMT 105Ile in the genotype was found for Mix B. In addition for this the HNMT T939C polymorphism (specifically the absence of the 939C allele in the genotype) made the 8 to 9 year old children more vulnerable to the adverse effects of the Mix A and B additive mixtures.
This study has shown that effects on behaviour may be associated with intake of some mixtures of specific food colours and the preservative sodium benzoate. Two mixtures were examined in unselected populations of 3 and 8/9 year olds. One mixture (Mix A) was shown to cause a significant increase in hyperactivity in one age group (3 year olds), while the second mixture (Mix B) caused significant effects in the other age group (8/9 year olds).
The size of the effects of the colour and preservative mixtures studied on the average hyperactivity score is lower than that reported for clinical samples. We recognise that hyperactivity is a behaviour influenced by a wide range of experiential and biological factors. It is known that there are major genetic influences on hyperactivity7 and this study has shown additionally that, when only children consuming more than 85% of the challenge drinks are considered, differential sensitivity to the mixture of food colours and preservative resulting from certain genetic polymorphisms is one route by which genetic influences on hyperactivity may be mediated. Although the results of the study suggest that some mixtures of certain food colours and benzoate preservative may effect the level of hyperactive behaviour in children, removal of these additives would not be a panacea for ADHD.
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