The debate over the link between the colourings used in soft drinks and hyperactivity in children has raged for many years but a new study by researchers at the University of Southampton may well have taken the debate to a new level. Ben Cooper assesses the impact the new findings may have for soft drinks producers.

The idea that a link exists between hyperactivity in children and the use of certain artificial colourings and preservatives in food and drinks is not new. Indeed, the issue is deeply embedded in the public consciousness, to the point that even without conclusive evidence the use of such ingredients has been declining steadily.

However, a British study published last week arguably provides the strongest empirical evidence to date of such a link, and may well accelerate the trend towards the removal of such additives from children's foods and drinks, both in the UK and elsewhere.

There are a number of reasons why this research, which looked at the effect of a mix of artificial food colours and sodium benzoate preservative on the behaviour of children in two age groups, could mark a significant moment in the debate. First and foremost, the study itself is the most extensive yet performed on the subject, and offers key points of difference from previous research.

Secondly, precisely because the subject has been of public concern for such a long time there is already a trend towards the removal of such products in the UK, as campaigning gathers momentum and retailers begin to see the value in marketing more "free-from" products. This study, particularly because it was commissioned by an official body, the Food Standards Agency (FSA), could see the debate reach a tipping-point. Moreover, with particular regard to the UK, there has been an early indication that the new Prime Minister may be more prepared to legislate in this area.

The FSA has also passed on the results to the European Food Safety Authority (EFSA), currently conducting a review into the safety of food colourings, so it may well have an influence in shaping EU policy.

Professor Jim Stevenson, who led the research group at the University of Southampton, believes it to be significant because of some fundamental points of difference from previous studies.

"There are a number of ways in which our study was an improvement on what had been available before," Professor Stevenson told just-drinks. "The first is a distinction. We were studying children from the general population rather than from special clinics." This may not only be significant from a scientific standpoint, but is also likely to increase the study's relevance and interest to the general public.

In addition, it was both larger, comprising a group of some 153 three-year-olds and 144 eight- and nine-year-olds, and conducted over a longer period of time than any previous study. "As far as I am aware there is no other study of this magnitude," Stevenson says. In addition, he points out, it had a more extensive control for placebo effects than any previous work, and also covered two distinct age groups.

So far, there has been little sign of a knee-jerk reaction by the FSA. The study was reviewed by the FSA's independent Committee on Toxicity (CoT), which said it provided supporting evidence suggesting certain mixtures of artificial food colours with sodium benzoate are associated with an increase in hyperactivity in children from the general population. If causal, the CoT's summary continues, this could be of significance for some individuals across the range of hyperactive behaviours, but could be more relevant to those at the upper end of the scale.

The FSA's revised guidance suggested that if a child shows signs of hyperactivity or Attention Deficit Hyperactivity Disorder (ADHD) then eliminating the colours used in the Southampton study from their diet might have some beneficial effects. In addition, the FSA said that if parents are concerned about any additives they should remember that, by law, food additives must be listed on the label so they can make the choice to avoid the product if they wish.

However, this response was criticised by some academics and pressure groups. Erik Millstone, professor of science policy at University of Sussex, said the response was inadequate. "Stevenson's team has robustly shown that food additives do adversely affect the behaviour, not only of children diagnosed as hyperactive, but normal healthy children too. The CoT pretends that these results have no implications for the general population or for food additives as a whole," Millstone said, calling for an end to official "complacency" on the issue.

For its part, the British Soft Drinks Association (BSDA) said it would study the research in detail, and supported the FSA's decision to pass on the results for consideration by EFSA. But the BSDA stressed that all additives being used in soft drinks in the UK were approved by the FSA, must by law be listed on labels, and were included to meet the expectations of the public about the appearance and shelf-life of products

However, it also acknowledged that consumer views on this subject were changing. "The soft drinks industry has always responded to changing consumer preferences and manufacturers have been and will continue to look at alternatives to the colours used in the study," the BSDA added.

The British Retail Consortium (BRC), which represents major retailers, emphasised that its members were steadily reducing the number of products containing such additives that they sold, largely in response to consumer demand.

Mounting public concern was also cited as a critical factor in the debate by Richard Watts, coordinator of the Children's Food Campaign at the food and agriculture pressure group Sustain. He said the public have generally been persuaded of some sort of link long before experts were, and that this latest research would have great resonance with consumers. Watts believes we are seeing a major shift in the debate as the public increasingly sees industry representatives as vested interests and regards the views of campaign groups as commanding greater validity.

Watts was also critical of the FSA's response. "That rather limp advice is the only confirmed change to their guidelines," he said. "I don't think they can hold the line here."

Another important factor is the willingness of Gordon Brown and his administration to support regulatory intervention. Some campaigners believe the new Prime Minister will be more prepared to support regulation than his predecessor. Gordon Brown's first statements on the matter, which were made at a Citizen's Jury in Bristol shortly after the results were published, certainly support that contention.

He said that all parents would be worried by the findings, adding that consumers could not be expected to check the ingredients of every item on the shelf and relied on the authorities to ensure there were no additives in food that put their children at risk. This could be seen as being at odds with the FSA's revised guidance. The Prime Minister called for a debate to decide what the right standards should be going forward. Some commentators have suggested Mr Brown will push for a stronger EU line on food additives.

This will certainly have given succour to campaigners who will be confident that the publication of the Southampton findings and the ongoing EFSA review will keep this issue in the public eye for some time to come. As a result, pressure on the food and drink industry and possibly on the FSA itself is only likely to intensify.