Autoimmune Thyroid Disease

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The effects of a double blind, placebo controlled, artificial food colourings and benzoate preservative challenge on hyperactivity

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The effects of a double blind, placebo controlled, artificial food colourings and benzoate preservative challenge on hyperactivity in a general population sample of preschool children

B Bateman, J O Warner, E Hutchinson, T Dean, P Rowlandson, C Gant, J Grundy, C Fitzgerald and J Stevenson

Aims: To determine whether artificial food colourings and a preservative in the diet of 3 year old children in the general population influence hyperactive behaviour.

Methods: A sample of 1873 children were screened in their fourth year for the presence of hyperactivity at baseline (HA), of whom 1246 had skin prick tests to identify atopy (AT). Children were selected to form the following groups: HA/AT, not-HA/AT, HA/not-AT, and not-HA/not-AT (n = 277). After baseline assessment, children were subjected to a diet eliminating artificial colourings and benzoate preservatives for one week; in the subsequent three week within subject double blind crossover study they received, in random order, periods of dietary challenge with a drink containing artificial colourings (20 mg daily) and sodium benzoate (45 mg daily) (active period), or a placebo mixture, supplementary to their diet. Behaviour was assessed by a tester blind to dietary status and by parents’ ratings.

Results: There were significant reductions in hyperactive behaviour during the withdrawal phase. Furthermore, there were significantly greater increases in hyperactive behaviour during the active than the placebo period based on parental reports. These effects were not influenced by the presence or absence of hyperactivity, nor by the presence or absence of atopy. There were no significant differences detected based on objective testing in the clinic.

Conclusions: There is a general adverse effect of artificial food colouring and benzoate preservatives on the behaviour of 3 year old children which is detectable by parents but not by a simple clinic assessment. Subgroups are not made more vulnerable to this effect by their prior levels of hyperactivity or by atopy.

Keywords: artificial food colouring; benzoate preservatives; hyperactivity; atopy; double blind placebo controlled challenge

Abbreviations: ADHD, attention deficit-hyperactivity disorder; APHR, aggregated parental hyperactivity ratings; AT, atopy; ATH, aggregated test hyperactivity; BCL, Behaviour Checklist; HA, hyperactivity; WWP, Weiss–Werry–Peters Activity Scale

There have been no population based studies examining the prevalence of hyperactivity related to intolerance to food additives following the initial claims of the detrimental effect of artificial additives on children’s behaviour.1 Subsequent studies, despite improved methodology, have failed to substantiate this claim2–7 or have only shown a small effect.8–18

A double blind placebo controlled high dose azo dye challenge in a highly selected group of children with behaviour disturbance suggested a small adverse effect on the children’s behaviour based on ratings on the Connor scale.16 There was no association between response and atopy, leading the authors to conclude that any effect was pharmacological rather than IgE mediated. Further clinical evidence from research on urticaria linked artificial food additive responses to IgE independent histamine (and other mediator) release.19 An in vitro study showed that circulating basophils released histamine in a non-IgE dependent response on exposure to azo dyes,20 and in an in vivo study in which high doses of tartrazine were administered to normal subjects induced significant histamine release.21 Despite this suggested mechanism of action there continues to persist, particularly in the public mind, links between “allergy” to artificial food additives and behaviour disturbance. The generalisability of findings from previous studies is limited by samples which are small, depend on an attention deficit-hyperactivity disorder (ADHD) diagnosis,9 are in patients already thought to show adverse behaviour triggered by artificial additives,16 or are recruited from specialist clinics.11 Some studies have identified a higher than expected proportion of atopic children within those whose behaviour appeared to be affected,13 but this has never been systematically examined.

The present study used population based screening to identify children with or without hyperactivity (HA) and with and without atopy (AT). Children were selected from this population for the dietary challenge phase of a within subject double blind placebo controlled study examining the impact of artificial colourings and benzoate preservatives on hyperactive behaviour. The study was designed to test the hypothesis that food additives have a pharmacological effect on behaviour irrespective of other characteristics of the child.16

The free full text for this abstract is available from the BMJ.

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Written by alienrobotgirl

2 September, 2006 at 5:04 pm

Posted in The Science of FCI

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