In the mid 1970s Dr Ben Feingold, a Californian allergist, generated a great deal of controversy with his claim that artificial colours and flavours and naturally occuring salicylates found in certain fruits could trigger hyperactivity in children.

Feingold claimed that 30-50% of the hyperactive children he had treated benefited from diets free of these substances. The Feingold diet quickly became famous and a great many studies were made to try to confirm his hypothesis but with mixed results. Most showed little or no effect.

However, in September, 2007, researchers at Southampton University (funded by the Food Standards Agency) reported the results of a study, which they claimed showed that mixtures of artificial colours and the preservative sodium benzoate affected the behaviour of 3 year old and 8 year old children.

The conclusions of scientists on the UK Committee on Toxicity (COT), who reviewed the study for the Food Standards Agency (FSA), were more tentative. The scientists noted that the observed changes in behaviour were small, and drew attention to inconsistencies in the results across the two age groups and between the two mixtures used in the study.

Nevertheless, the evidence overall was enough to persuade the FSA to issue new advice to parents and, at the same time, to call on UK food manufacturers for a voluntary ban on the colours by 2009.

The Southampton study was also reviewed by scientists at Europe’s food safety watchdog, the European Food Safety Authority (EFSA), with the help of experts in behaviour, child psychiatry, allergy and statistical analysis. The EFSA team carried out a re-analysis of the results using what it called ‘a more justifiable and conventional statistical model’.

The overall finding of the EFSA team’s review was that the clinical significance of the observed effects was unclear – they were not convinced that the small alterations in attention and activity found in the study would actually interfere with schoolwork and other intellectual functioning.

Nevertheless, EU member states and MEPs have agreed on the need for EU-wide legislation in this area and foods containing the colours must now be labelled “may have an adverse effect on activity and attention in children”. The colours in question are sunset yellow (E110), quinoline yellow (E104), carmoisine (E122), allura red (E129), tartrazine (E102) and ponceau 4R (E 124).

The FSA’s latest advice is that a child showing signs of hyperactivity might be helped by eliminating the artificial colours used in the study from their diet – at the same time reminding parents that there are many factors associated with this complex condition.