Artificial food colourings and preservatives have a "significant" impact on hyperactivity levels in very young children, finds research in Archives of Disease in Childhood.
Removal of these substances could be in the long term interest of public health, say the authors.
The authors base their findings on over 1800 three year old children, who were screened for hyperactivity and allergies.
Almost 300 children, divided into four groups, completed the four week study. During the first week, the children ate only foods free of artificial additives, including colourings, such as tartrazine, sunset yellow, and carmoisine, and the preservative sodium benzoate.
During the second and fourth weeks they were randomly assigned to a daily dose of fruit juice, with or without colourings and preservatives.
The children's behaviour was assessed before the study began and regularly throughout the study period by formal clinical assessment and parental diaries. The parents were unaware which type of juice had been given to their child.
Parental ratings showed that the children became significantly less hyperactive during the period when the additives were removed from the diet, and much more hyperactive when they were put back in.
The authors suggest that for those children with high hyperactivity scores, this translates as a reduction in prevalence from 15% to 6%. But this figure must be interpreted with caution, they say.
These changes were not reflected in the formal clinic assessments. But the authors suggest that parental ratings might be more sensitive as parents see their children's behaviour over a longer period of time, in more varied settings, and in less optimal conditions.
Children with more extreme forms of hyperactivity were no more or less likely to respond to dietary changes than children at the milder end of the behavioural spectrum. And the effects were seen irrespective of whether the child was hyperactive or allergic before the study began.
Previous research has shown that young hyperactive children are at risk of continuing behavioural difficulties, such as poor social adaptation and educational problems, say the authors, pointing out that there could be a potential long term public health benefit, if this issue were addressed.
"These findings therefore suggest that significant changes in children's hyperactive behaviour could be produced by the removal of artificial colourings and sodium benzoate from their diet," they conclude. Studies should be undertaken to see if the same effects might be seen in older children as well, they suggest. http://www.bmj.com
From Southampton University the following.
A group of scientists at the University of Southampton has completed a study to determine whether artificial food colourings and a preservative in the diet of three-year-old children in the general population influence hyperactive behaviour. Parents reported a general adverse effect from artificial food colouring and a benzoate preservative on the behaviour of three-year-old children but this was not detected by assessments performed in clinics. These findings are being published in the Archives of Disease in Childhood in the June 2004 issue.
For this study a total of 277 three-year-old children on the Isle of Wight were recruited. Their parents had to keep them on a diet carefully chosen to be free of the additives. In certain weeks, the children were then given a daily drink that either contained the additives or an identical looking and tasting fruit drink. Neither the parents nor the children knew which type of drink was being given although the study design meant that they knew when they were being tested
It was found that parents reported more disruptive and inattentive behaviours on those weeks the children received the drinks with additives, even though the parents did not know which drink was being taken. The study also found that some parents reported poorer behaviour by their children even when they had only been given the pure fruit drink.
The study was funded by the Food Standards Agency and was a collaboration between the School of Medicine and School of Psychology at the University of Southampton, and staff at the David Hide Asthma and Allergy Centre, St. Mary's Hospital, Isle of Wight.