Chocolate and children: a
critique
by Sue Dengate
Introduction
A
* Reason for study: to investigate the ‘popular belief’ that chocolate adversely affects
young children’s behaviour.
* The study:
the researchers videotaped 26 preschoolers while they listened to a story for
seven minutes. The children were then given three Freddo chocolate frogs or an
equivalent weight of sultanas (dried grapes). After 30 minutes, the children
were again videotaped for seven minutes while listening to another story. The
study was conducted in three preschools over two mornings, before morning tea,
one week apart, with the order of presentation of dried fruit or chocolate
varied. Independent raters used the videos to assess the children’s activity
levels and concentration (Ingram and Rapee, 2006).
* Results:
there were no significant differences in the children’s ‘before’ and ‘after’
behaviour with either chocolate or fruit, Researchers concluded that ‘giving a
moderate amount of chocolate to young children appears to have no more adverse
effects on their behaviour than giving them dried fruit’. The researchers did find,
however, that there were differences in the children’s baseline behaviour
(behaviour was significantly worse - both before and after - on fruit days).
Researchers suggested that parents may be misinterpreting changes in children’s
behaviour as due to chocolate when it could be the excitement of a birthday
party or irritability after a day at kindergarten.
* Selection of participants excluded children likely
to react: 26 children were recruited
from three preschools. None of the children were identified as having a
developmental disability, a history of hyperactivity, or a major adverse
behavioural reaction to chocolate. It is estimated that one child in six
suffers from a development disability (Grandjean and Landrigan, 2006) thus
children who were most likely to be affected were not included in this study.
An entire class of children would have been a more representative sample.
* Superficial literature survey: The researchers wrote ‘there have been no direct
investigations into the behavioural response to chocolate consumption’ while
ignoring successful diet studies which
conducted chocolate challenges as part of an elimination diet and challenge
protocol. In trials of the Few Foods elimination diet, Egger et al (1985) and
Carter et al (1993) found about 60% of subjects responded to chocolate
challenges, the latter in double-blind placebo controlled trials. Food chemical
elimination diets, however, use a different method. They focus on removing food
chemicals such as additives, salicylates and amines from the diet, and
reintroduce chocolate as part of the test for reactions to biogenic amines such
as tyramine. Swain et al (1985) found a
high proportion of reactions to amines in 86 hyperactive children, although
significantly fewer than those who reacted to salicylates. For some children,
chocolate is a safe treat that does not contribute to hyperactivity. For
children who are sensitive to amines, it is not.
* Unstable baseline: the ‘gold standard’ for food challenge testing is the double blind
placebo controlled challenge, preceded by some form of an elimination diet to
achieve a low and stable baseline before challenges. Baseline readings as
reported in this study were not stable, as shown by significantly different
baselines on fruit versus chocolate days, which were dismissed by the authors
as due to ‘unpredictability of children in general’.
* Lack of theoretical
framework for food reactions: immunoglobulin E (IgE) antibodies, overabundant
in people with allergies and linked to wheezing, sneezing, itching and
swelling, were first isolated and described in the 1960s. Although many
food-behaviour researchers In the 1970s and 80s assumed that behaviour food
reactions were “allergies” more recent research has showed that behavioural
reactions to foods are not related to IgE mediated allergy, but seem to be
pharmacological reactions to food chemicals such as amines in chocolate, which
are characterised by dose-related, cumulative and delayed reactions (Clarke et
al, 1996). Macquarie researchers, apparently
unaware of these studies, assumed that any possible effects of chocolate would
be due to sucrose or caffeine, despite quoting studies showing that neither
sugar or caffeine are related to children’s behaviour.
* Placebo not neutral: sultanas were chosen for as the placebo because they
are a ‘healthy’ food that researchers assumed would not affect children’s
behaviour. In fact, sultanas contain high levels of natural amines – the
chemical also in chocolate – as well as salicylates. Studies show that
salicylates affect children’s behaviour and that more children are affected by
salicylates than amines (Swain et al, 1985, Breakey 1991) so in this case the
placebo would be more likely to cause a reaction than the chocolate, although
not within the limited time frame for observations chosen by the researchers.
* Limited timing of observations: children were observed for 7
minutes, half an hour after the ingestion of the food. This very limited timing
was based on a small study twenty years ago that purported to show behavioural
effects of sugar 45-60 minutes after ingestion of sugar, apparently because
researchers assumed they were testing the effects of sugar in chocolate. In
fact, reactions due to food chemicals can be delayed for hours or even days
(Loblay and Swain 1986, Clarke et al 1996), and as many parents in the Food
Intolerance Network have discovered, behavioural reactions to amines can be one
of the slowest of all reactions. In this situation, we would have predicted no
reaction to either salicylates or amines within 40 minutes and that is exactly
what happened.
* What this study showed: a small group of
preschool children had no reaction to 3 Freddo frogs within 37 minutes of
ingestion.
* What this study didn’t show: that children’s behaviour at birthday parties is
due to excitement rather than additives such as artificial colours and MSG.
* What the media reported: Cognitive Daily headlined it as ‘don’t let your
kids read this entry (Chocolate doesn’t make them hyperactive)’. The author
leapt from the study’s limited finding about chocolate to the wider conclusion
based on the researchers discussion: ‘this suggests that other phenomena such
as weather, other goings on in the classroom and so on are much more likely to
affect behaviour than the particular food a child eats’ as did most others,
including dietitian Nicole Senior in a popular magazine widely read by parents.
* What this study didn’t report: why the chocolate was called Freddo Frogs but the
brand of the sultanas wasn’t revealed
* Implications for parents: independent
scientists report that some children can be severely affected by some foods and
that ignoring or denying the effects of foods is not helpful for families (Jacobson
and Schardt, 1999). Once again, parents and children lose out. This study gives
no constructive suggestions for parents who are having trouble controlling
their children, children who constantly feel irritable or aggressive, or for
teachers with such students.
* My Conclusion: due to the superficial literature survey in this study, the authors
failed to grasp the complexity of food intolerance and carried out a pseudo-scientific
study that gives the food industry another reason to bully parents, while
denying parents the right of reply.
References
Breakey J, Hill M, Reilly C,
Connell H. A report on a trial of the low additive, low salicylate diet in the
treatment of behaviour and learning problems in children. . Aust J Nutr Diet
1991;48(3):89-94.
Carter CM, Urbanowicz M,
Hemsley R, Mantilla L, Strobel S, Graham PJ, et al. Effects of a few food diet
in attention deficit disorder. Arch Dis Child 1993;69(5):564-8.
Clarke L, McQueen J, Samild
A, Swain A. The dietary management of food allergy and food intolerance in
children and adults. Australian Journal of Nutrition and Dietetics
1996;53(3):89-94.
Egger J, Carter CM, Graham
PJ, Gumley D, Soothill JF. Controlled trial of oligoantigenic treatment in the
hyperkinetic syndrome. Lancet 1985;1(8428):540-5.
Grandjean P, Landrigan PJ,
Developmental neurotoxicity of industrial chemicals. Lancet 2006;368(9553):2167-78.
Ingram M, Rapee RM, The
effect of chocolate on the behaviour of preschool children. Behavior Change 2006:23(1);73-81.
Jacobson MF, Schardt MS. Diet, ADHD and behaviour: a quarter-century
review.
Loblay RH, Swain AR. 'Food
intolerance'. In Wahlqvist ML, Truswell AS, Recent
Advances in Clinical Nutrition.
Munger, D. Don't let your
kids read this entry (Chocolate doesn't make them hyper)
Senior, Nicole, ‘Did you
know: although many parents believe junk food causes hyperactivity in their
children, there seems to be little scientific evidence to support this’, Super
Food Ideas Magazine, April 2007, page 12. www.superfoodideas.com.au
