A programme broadcast on UK television this week offered damning evidence of the effect of food additives on children.

In an experiment highlighted in the ITV1 programme Tonight With Trevor McDonald, five-year-old twins Christopher and Michael Parker were fed strictly controlled diets over a two-week period. Christopher continued with his normal diet, while Michael only ate food completely free of additives.

Michael was described by the twins' mother Lynn Parker as showing greater assertiveness and being calmer than his twin after the two week period. She added that he had developed a sense of humour and was more communicative.

Michael also showed a stronger performance in IQ tests carried out at the end of the test period. In IQ tests before the experiment the twins each made the same mistakes and completed them in exactly the same time. Two weeks later Michael's results had improved by 25% while Christopher's had improved by just 10%.

Maurice Hansen, author of E for Additives, told BBC News Online: "Children who eat a lot of undesirable additives throughout their life and the bad food that goes with undesirable additives are going to finish up with a declining educational standard with a declining behavioural standard."

He said if undesirable additives were removed from a child's diet he would expect that child to show better concentration, increased IQ and be better behaved.

The experiment's findings will add grist to the mill of campaigners lobbying for rules on the use of additives in children's food.