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.

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 condition.

As a precautionary measure, the FSA called on UK food manufacturers to remove the artificial colours from their products and has held meetings with industry representatives to monitor progress.

The Southampton study has also been 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’. They found that “the study provided limited evidence that the mixtures of additives tested had a small effect on the activity and attention of some children”, noting that “the effects observed were not consistent for the two age groups and for the two mixtures”.

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.

EFSA therefore concluded that “the findings of the Southampton study could not be used as a basis for altering the Acceptable Daily Intake (ADI) of the respective food colours and sodium benzoate”.

A summary of the review - and the full report – can be found on EFSA’s website.

The questions raised by EFSA were considered by the Food Standards Agency at its April Board meeing. In spite of EFSA's doubts about the study, the FSA decided to call for a mandatory EU-wide ban on the six colours - a move which seems unlikely to succeed, given EFSA's official role as scientific advisor to EU law makers. Meanwhile, the FSA continues to press UK food manufacturers for a voluntary ban on the colours by 2009.

In spite of the questions raised by EFSA, there have been calls in some quarters for an EU-wide ban on the six colours used in the study. The EU member states and Parliament have rejected such calls, but agreed that foods containing the colours will in future have to 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). EU regulations are expected to be finalised later in the year.