The Importance of Dietary Exposure Assessments when Studying the Adverse Effects of Food Additives

E numbers are additives that have been approved for use in the European Union, and include colours, flavours, and preservatives which are used to make food safer, as well as look and taste better. The safety of using these additives in foods is taken very seriously, with regulatory bodies like the European Food Safety Authority (EFSA) allocating Acceptable Daily Intakes (ADIs) for consumers and Maximum Permitted Levels (MPLs) for several E numbers in foods.

One study in particular generated a lot of controversy about the alleged link between hyperactivity in children and artificial food colourings and the preservative sodium benzoate. The study (commonly referred to as the Southampton study due to where it was conducted) was published in 2007 and involved 153 3-year old and 144 8/9-year children, who were given a juice cocktail of six colours and one preservative over a six week period. The study was randomised, double-blinded and placebo-controlled, and the children were placed on an additive free diet for the duration of the study (apart from the cocktail). The study concluded that children who consumed the cocktail showed a “significant adverse effect” compared with the placebo. The adverse effects were determined using four measures: the Global Hyperactivity Aggregate (GHA), the abbreviated ADHD rating scale IV, the abbreviated Weiss-Werry-Peters (WWP) hyperactivity scale, and the Conners Continuous Performance Test II (CPTII). These measures were determined based on ratings by parents, teachers, and psychology graduates over the course of the study. The researchers were not able to ascertain which additives were causing problems, but their main conclusion was that artificial colours or a sodium benzoate preservative in the diet resulted in hyperactivity in 3-year-old and 8/9-year-old children in the general population.

There were several consequences as a result of the study. EU regulation was amended; foods containing the additives used in the study were required to carry the warning “may have an adverse effect on activity and attention in children”. ADIs of three of the colours were lowered by EFSA. The UK government even supported a voluntary ban on the six food colours, and many branded products have since removed the additives in question.

In 2009, an interesting follow-on study was conducted by a group of researchers in UCD, who sought to find out what the pattern of intake of the additive cocktail actually is in Irish teens and children. To do this, they used the Irish national food consumption diaries for teens and children and the Irish National Food Ingredient Database (INFID) to determine dietary exposure to the additives. To assess what the dietary exposure to additives could be, they made the assumption that if the additive was present, it was present at its MPL. Their study yielded some interesting results.

The majority of additive-containing foods consumed by teens and children did in fact contain one of the target additives. However, no food contained all seven of additives used in the Southampton study. Furthermore, only 16% of all meals/snacks were found to contain more than one of the target additives, and no child or teenager ever achieved the overall intakes used in the Southampton study. And this was using the conservative assumption that additives were present at their Maximum Permitted Level, which would typically lead to an over-estimation of dietary exposure. Thus, it can be safely concluded that no Irish child or teenager ever receives the kinds of doses used in the Southampton study.

This is not to say that the results of the Southampton study are no longer valid; they are. However, hyper-dosing children with additives at levels that never occur in real-life isn’t necessarily the best way to legislate the use of food additives. The key point is that when performing a risk-assessment based on the results of the study, it is only by considering dietary exposure that you can determine what the consumption of the additives actually is in reality.


D. McCann, A. Barrett, A. Cooper, D. Crumpler, L. Dalen, K. Grimshaw, E. Kitchin, K. Lok, L. Porteous, E. Prince, E. Sonuga-Barke, J. O. Warner, J. Stevenson, “Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial”, Lancet 2007; 370:1560-67.

A. Connolly, A. Hearty, A. Nugent, A. McKevitt, E. Boylan, A. Flynn, M.J. Gibney, “Pattern of intake of food additives associated with hyperactivity in Irish children and teenagers”, Food Additives and Contaminants, 2009, 1-10.

Written by Mark Lambe on May 11 2011

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