Britain’s food watchdog is warning all parents today of a clear link between additives and hyperactive behaviour in children.

Research for the Food Standards Agency (FSA) and published in The Lancet has established the “deleterious effects” of taking a mixture of artifical extras that are added to drinks, sweets and processed foods. It has led the FSA to issue the advice to parents who believe their children to be hyperactive that they should cut out foods containing the E numbers analysed in the study.

Scientists from the University of Southampton, who carried out research on three-year-old and eight-year-old children, believe that their findings could have a “substantial” impact on the regulation of food additives in Britain. But the FSA has been accused of missing an opportunity to protect children and all consumers by failing to impose a deadline on manufacturers to remove additives such as Sunshine Yellow and Tartrazine from their products.

In the biggest study of its kind the researchers recorded the responses of 153 three-year-olds and 144 eight to nine-year-olds to different drinks. None suffered from a hyperactivity disorder.

The children drank a mix of additives that reflected the average daily additive intake of a British child. The mixture was not a product currently on sale.

After consuming the drinks – a cocktail of controversial E numbers and the preservative sodium benzoate – the children were found to become boisterous and lose concentration. They were unable to play with one toy or complete one task, and they engaged in unusually impulsive behaviour. The older group were unable to complete a 15-minute computer exercise.

Results varied between different children but the study found that poor behaviour was observed in children who had no record of hyperactivity or attention deficit disorder.

The results are certain to cause concern and it is likely many parents will remove or cut down on food and drink products that might provoke such reactions in their children. The problem for many parents will be how to police children’s eating; although most foods are labelled, some sweets are sold loose in shops and school canteens.

Schools can now expect to be inundated with requests for the ingredients of food and drink on offer to their pupils to be made known.

Jim Stevenson, head of psychology at the University of Southampton, who led the research, said yesterday that he thought there could be swift action against artificial colourants but that it could take longer to phase out use of the preservative sodium benzoate.

At a briefing to publicise the results, however, he said that the FSA’s advice was the most sensible course of action at present. Hyperactive behaviour was also caused by genetic, developmental and emotional factors and a change of diet was not a panacea.

But Richard Watts, food campaigner for the pressure group Sustain, said that the advice would cause confusion. “The agency needs to toughen up the rules quickly. I don’t know why they did not give food companies a deadline to remove the additives. I think as an urgent next step any food with these additives should be classed as junk food and banned from TV advertising to children.” He was also concerned about soft drinks available in schools and wanted the School Foods Trust to review the use of sodium benzoate.

Ian Tokelove, spokesman for the Food Commission, said: “Manufacturers should clean up their act and remove these additives, which are neither needed or wanted in our food”.

The FSA defended its stance and said the matter had to be resolved by the European Commission. Dr Clare Baynton, of the FSA, made it clear that the additives were safe and approved for use in food, and that further assessment was required. She put the onus on parents to monitor their children’s diet. “It is for a parent to know what foods their children are susceptible to and whether their children react to to specific types of food.”

The study builds on tests conducted on the Isle of Wight in 2002 which were inconclusive about links between additives and hyperactivity.

Julian Hunt, of the Food and Drink Federation said: “It is important to reassure consumers that the Southampton study does not suggest there is a safety issue with the use of these additives. In addition, the way in which the additives were tested as a mixture is not how they are used in everyday products.

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