A trial of removing food additives should be considered for hyperactive children.
A properly supervised trial eliminating colours and preservatives from the diet of hyperactive children should considered a part of the standard treatment, says an editorial in this week's BMJ.

Although a substantial body of evidence shows a link between attention deficit hyperactivity disorder (ADHD) and artificial food colourings and preservatives, removing them is still considered as an alternative rather than a standard treatment for ADHD, writes Professor Andrew Kemp from the University of Sydney.

In contrast, despite a lack of evidence for its effectiveness, the use of alternative medicine is widespread - up to 50% of children attending tertiary children's hospitals in the UK and Australia have used it in the past year.

Of the three main treatments for ADHD in children - drugs, behavioural therapy, and dietary modification - only drugs and dietary modification are supported by data from several trials. Yet, behavioural therapy, which has no scientific evidence base, is still thought of as necessary for "adequate treatment", he says.

So why, despite evidence to the contrary, does the removal of food additives remain an alternative rather than a standard part of treatment for ADHD, asks Kemp?

Data published in 2007 showed that normal (not hyperactive) children were significantly more hyperactive after they ate a mixture of food colourings and a preservative (sodium benzoate), with obvious implications for children with ADHD.

In light of these findings, the European Food Safety Authority (EFSA) reviewed the evidence linking preservatives and colourings with hyperactive behaviours from 22 studies between 1975 and 1994 and two additional meta-analyses.

16b of the studies reported positive effects in at least some of the children. However, the EFSA pointed out that hyperactivity has a wide range of social and biological causes, and exclusively focusing on food additives may " detract from the provision of adequate treatment" for children with the disorder. But, argues Kemp, to discount the accumulating evidence of dietary factors may also do this.

Increasing numbers of children are taking drugs for hyperactivity - 2.4% of children in the state of Western Australia. Removing colours and preservatives is a relatively harmless intervention, so a properly supervised and evaluated trial period of eliminating them should be considered as part of the standard treatment, he concludes.