Food safety authorities in Ireland and Britain have advised parents worried about their children's behaviour to avoid certain artificial food colourings following the release of a study which links the colourings to hyperactivity and an inability to concentrate.
The colourings are commonly found in sweets, drinks and snack foods consumed by children.
The study, published online today in the medical journal The Lancet, found that the artificial colourings "exacerbate hyperactive behaviours in children at least up to middle childhood".
The colourings can affect all children, not just those with extreme hyperactivity (ADHD), the researchers found. The additives appear to affect children's concentration.
The study, conducted by staff at the University of Southampton and the Department of Paediatrics, Imperial College, London, was commissioned by the UK Food Standards Agency, which immediately issued a warning to "parents of children showing signs of hyperactivity".
"Eliminating certain artificial food colours from their diets might have some beneficial effects on their behaviour," the agency stated.
The Food Safety Authority of Ireland followed suit with this warning: "Parents of children in Ireland who display symptoms of hyperactivity or of Attention Deficit Hyperactivity Disorder (ADHD) should consider limiting their children's consumption of food products containing these food colours."
In the study, parents, teachers and researchers were trained to observe and record the behaviour of two groups of children: three-year-olds and eight/nine-year-olds. Some of the children were given a placebo, while others were given a cocktail of colourings equivalent to those found in two bags of sweets.
Both age groups showed significant behavioural changes after they had consumed the additives, said Prof Jim Stevenson, of the University of Southampton, one of the researchers who undertook the study.
"We're not talking about temper tantrums, we're not talking about aggression, we're talking about children who move around a lot, who fidget, who change their focus of attention quickly, who act impulsively, who do the first things that come into their minds," Prof Stevenson told The Irish Times.
The behaviour of some children altered dramatically, while other children did not change at all. However, on average, most of the children were significantly affected by the colourings, the study found.
The artificial colourings studied were the ones most commonly found in food eaten by children. All these products are identified on food packaging either by their name or the "E" number.
In its statement, the Food Safety Authority of Ireland recommended "that parents read food labels when buying products so that they can identify if they contain these food colours and thus make an informed purchasing decision".
Because the children consumed a mixture of the colourings, Prof Stevenson said more study was needed to determine whether the colourings affected behaviour to different degrees. Until then, if parents were concerned about their children's behaviour, these were "the ones to avoid".
The study results were not surprising, said Margot Brennan, public relations officer for the Irish Nutrition and Dietetic Institute. Children needed to cut back on the types of foods which contain colourings, she said. Irish children consumed too many processed and junk foods and needed to eat more fresh produce.
E numbers: artificial colourings studied
Tartrazine E102
Ponceau 4R E124
Sunset Yellow E110
Carmoisine E122
Quinoline Yellow E104
Allura Red E129