Preventing childhood obesity by reducing consumption of carbonated drinks: cluster randomised controlled trial
BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.38077.458438.EE (Published 20 May 2004) Cite this as: BMJ 2004;328:1237All rapid responses
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Competing interests:
None declared
Competing interests: No competing interests
Is there a working explanation for this result in view of the non
caloric carbonated drinks?
I have had a personal interest in this concept for some time. For
example, what explains the negative impact of carbonated beverages with
seborrheic dermatitis? Clearly this is a systemic effect.
I offer the thought of investigating the possible effect of surface
disruption of the oral and gastric surfaces by the carbonation and what
the consequences of this even may be.
I have some additional thoughts but I'll leave it at a general
concept at this point.
Kenneth B. Peterson MD
Internal Medicine
Competing interests:
None declared
Competing interests: No competing interests
The statement by James et al suggesting that carbonated drinks
contributes to childhood obesity was supported in a cross-sectional study
conducted on 93 Primary School children aged 10-11 from three different
schools in Birmingham in March 2004. The aims of this study were to
examine how large a factor diet and exercise play in determining a child’s
Body Mass Index (BMI).
Questionnaires were given out at random consenting schools across
Birmingham, and parental consent was obtained for each child to be
involved in the study. The questionnaire focused on the lifestyle and
dietary intake of each child. Of the 93 study subjects, 1% were
underweight, 69% were of normal weight, 18% were overweight and 12% were
obese, according to the standard classification of BMI for children1. 39%
of normal and underweight subjects participated in greater than 5.5 hours
of exercise a week, compared to 24% of overweight and obese subjects.
This was not statistically significant, but other studies2 have produced
similar trends which have been significant, suggesting the result is most
likely to be a valid reflection of reality. Analysis by logistic
regression showed that low levels of exercise (<2 hrs/wk) may increase
the risk of obesity by up to 30 times, compared to high levels of exercise
(>5.5hrs/wk). However, a child’s estimation of the time spent doing
various activities may be unreliable due to the difficulties in measuring
this quantity.
The questionnaire also asked about the intake of junk food, which
consisted of carbonated drinks, sweets, chocolates and crisps. Despite
the study showing that low levels of junk food appeared beneficial in
preventing children from becoming obese, no conclusive evidence was found
to link junk food intake with BMI.
Therefore, exercise has been found to play a significant role in a
child’s weight, which corroborates opinions expressed by Des Spence3, in
reference to the study by James et al4. However, contrary to the former’s
belief that “Childhood obesity is not caused by diet”, obesity has a
multifactorial cause5, of which diet plays a significant part; and despite
our study having no conclusive evidence for junk food (which includes
carbonated drinks) affecting a child’s weight, the study population was
not large enough to definitely rule out a large intake of junk food as a
causative factor. Hence, our study offers support to James et al’s
statement that the consumption of carbonated drinks, sweetened with sugar,
contributes to obesity in children.
1 Cole TJ, Freeman JV, Preece ME. Boys and girls BMI chart, Body Mass
Index reference curves for the UK, Arch Dis Child 1995;73:25-29
2 Tremblay MS, Wilms JD. Is the Canadian childhood obesity epidemic
related to physical inactivity? International Journal of Obesity
2003;27:1100-1105
3 Spence, D. Childhood obesity and consumption of fizzy drinks, diet
is not that important in obesity. BMJ 2004;329:54 (3 July)
4 James J, Thomas P, Cavan D, Kerr D. Preventing childhood obesity by
reducing consumption of carbonated drinks: cluster randomised controlled
trial. BMJ 2004;328:1237 (22 May)
5 Prentice Am. Overeating: The health risks. Obesity research
2001;9:S234-S238
Competing interests:
None declared
Competing interests: No competing interests
It's common knowledge that fizzy drinks are bad for you.It is said
that a glass of cola contains about 7-8 teaspoons of sugar.Diet colas
containing artificial sweetners are equally bad providing just empty
calories.If this is the case its no wonder that drinking them increases
obesity. Its quite sad to overweight children knowing the health problems
they are going to have as adults.But what is more important is what we can
do about it?
Its not easy to convince children that something they like and enjoy
so much is not good for them especially with the pull of peer pressure and
television advertisments.It would be next to impossible in those children
whose parents are regular cola drinkers-after all children do learn from
their parents!
Its not possible to come up with a magic wand to stop children
drinking cokes but we could try our best to develop a healthy diet when
they are quite young in life.The first and the most important thing would
be for parents to set a good example for their kids.Switch the fizzy
drinks for some fresh juice or milk shakes.Take kids out to play,encourage
them to enjoy the outdoors instead of spending time in front of the
television/ computer.Its time we seriously start thinking of what obesity
is going to do for our next generation.
Competing interests:
None declared
Competing interests: No competing interests
Sir:
This study directly targets one very well known factor, i.e.,
consumption of carbonated drinks rich in sugar in the etiology of obesity
in school children, which is a major public health problem and also
reported to have multiple biopsychosocial consequences in adulthood, some
of which such as myocardial infarction and strokes are fatal while others
such as diabetes, musculoskeletal disorder, depressions and eating
disorders are chronic in nature. Notably, schools are the places where
effective educational messages as evident in this study (1) can get
through a large number of targeted population of children and adolescents
who have tendency to become pathologically obese.
Certainly, a proportion of children in schools are not obese at all,
though they are cosuming carbonated drinks like their counterparts who are
obese. Likewise, a proportion of children are obese, though they are not
consuming rather avoiding carbonated drinks. Thus, four groups of children
could be identified in schools, 1) obese drinking carbonated drinks, 2)
obese but not drinking carbonated drinks, 3) not obese but drinking
carbonated drinks, and 4) neither obese nor drinking carbonated drinks.
Hence, accordingly this study has only addressed and targeted about one
quarter of population of school children. One interesting question emerges
is that why children not obese and drinking carbonated drinks should or
should not continue driking such enjoyable drinks? Simply the answer is
"no" because over a two year period or so they are also likely to be
obese.
Finally, I feel that the preventive strategies targeting only single
etiological factor in the complex disorder like obesity will not have much
successful and sustained effective effects on longterm basis.
Reference:
Janet James, Peter Thomas, David Cavan, and David Kerr. Preventing
childhood obesity by reducing consumption of carbonated drinks: cluster
randomised controlled trial
BMJ 2004; 328: 1237-0
Competing interests:
None declared
Competing interests: No competing interests
Childhood obesity is no doubt a serious health care concern with its
deleterious effects on the society as a whole. Measures to decrease its
menace should focus at promoting overall healthy lifestyle habits in
children rather than focussing on any one aspect responsible for it.
Reduction of carbonated drinks undoubtedly reduces the energy consumption
and thereby the obesity levels in young children. However an analysis of
factors responsible for an increase in these drinks needs to be done to
prevent their overconsumption.
Studies(1,2) have found out that an increase in the indoor activities like
television viewing, working on computers etc. has brought about an
increase in the consumption of junk foods and carbonated drinks. This also
means a reduction in the outdoor playing activities thereby decreasing the
total energy expenditure by the children. These problems are being
aggravated by the parental pressures to perform well on the academic front
thereby decreasing further the time spent in outdoors by the children.
A strategy thus needs to be developed comprising of healthy eating habits,
maximising outdoor activities and restricting the number of television
viewing hours thereby decreasing the factors responsible for the
consumption of junk foods and carbonated drinks and hence their effects on
the health of children.
References:
1)Matheson DM, Killen JD, Wang Y, Varady A, Robinson TN.Children's food
consumption during television viewing.
Am J Clin Nutr. 2004 Jun;79(6):1088-94.
2)Crespo CJ, Smit E, Troiano RP, Bartlett SJ, Macera CA, Andersen
RE.Television watching, energy intake, and obesity in US children: results
from the third National Health and Nutrition Examination Survey, 1988-
1994.
Arch Pediatr Adolesc Med. 2001 Mar;155(3):360-5.
Competing interests:
None declared
Competing interests: No competing interests
EDITOR--It was interesting to read the paper of James et al (BMJ
2004;328:1237), Preventing childhood obesity by reducing consumption of
carbonated drinks: cluster randomised controlled trial.
My comment:
Recently there were many papers on three areas which have
psychological, physical, and social consequences on the person concerned
and the Society. They were published in different medical journals among
which is the BMJ. I was surprised recently about the content of caffeine
in many of the popular drinks like Coca Cola and Pepsi! I think the
Govermental authorities of which the Health authority is one of them ought
to take that seriously before further deterioration.
Thanking you
Competing interests:
None declared
Competing interests: No competing interests
As Professor Greenhalgh aptly notes in her response, perhaps the
greatest difficulty ahead will be to disentangle commercial interests of
the food industry from the services and needs provided by those in
supportive or nurturing roles.
Commercial interests extend to a marketing opportunity for all
occasions including dietary regimes for weight loss. Weight-loss and
“healthy eating products” are sometimes anything but nutritious if you
examine the overall salt, sugar and fat listed in the ingredients.
Currently the mixed health messages on Obesity and nutrition overlook
a significant subsection of the adult population who are targeted by media
and mimetic desire of next to transparent role models, or through poverty
stand beyond it.
I refer you to
SACN findings of the national diet and nutrition survey
http://www.sacn.gov.uk/pdfs/sacn_04_04.pdf
Perhaps noting:
Page 5 Item 12/
Page 11 Item 51/
Page 13 Item 67
Which comments on the shocking rise in soft drink consumption.
Though you may also care to consider:
Page 13 Item 69.
Obesity is a very visual measure of unhealthy nutritional status,
there is good cause to examine less apparent sectors of the population who
may be overlooked by this measure alone (1) You will note that the survey
did not encompass those over the age of 64 for whom soft or carbonated
drinks may not figure largely in their overall intake. Were they or are
they to be considered as a separate and distinct entity in a parallel or
future survey for the non-economically productive?
Perhaps an overall goal of achieving an entire population with both
equal access to health information and economic ability to purchase
affordable nutritionally desirable foods (2) which are not always the most
inexpensive, without the accompanying raucous food industry advertising
strategies designed to tap into self-image, status desire or inappropriate
sponsorships.
Though instigation and maintenance of adequate early nutritional
balance is a key message, from a lay “gardening” perspective, any stressor
on my tomato plants throughout their lifecycle will alter the nature of
the fruit produced, be it shrivelled, swollen or split.
(1) BMJ 1997;315:338-341 (9 August)
Evaluation of validity of British anthropometric reference data for
assessing nutritional state of elderly people in Edinburgh: cross
sectional study
Bannerman et al
(2) http://www.nature.com/cgi-
taf/DynaPage.taf?file=/ejcn/journal/v58/n6/abs/1601889a.html
Dietary intakes of adults in the Netherlands by childhood and
adulthood socioeconomic position
Competing interests:
None declared
Competing interests: No competing interests
Great study, and underscores clinical intuition about why kids are
more obese these days. Wearing my hat of school governor, I've been
trying to introduce a healthy eating policy to our local school. It was
relatively easy to get the catering contract changed to a company that
guarantee to use fresh veg, low salt, less fat etc, but it was much more
difficult to influence the policy on soft drinks machines. Reason - the
latter are a critical source of income for a cash-strapped school that has
seen its budget squeezed in real terms year on year. Sales from vending
machines are now used to pay for books and equipment - and I suspect it
won't be long before the school advertises for a 'Coca-Cola head of
chemistry' or a 'Fanta French teacher'.
Perhaps it's time the BMJ launched a new journal: 'Sugar Control'?
Competing interests:
None declared
Competing interests: No competing interests
My take on the studies limitations.
The first study, ‘Preventing obesity by reducing consumption of
carbonated drinks: cluster randomised controlled trial’ (James, Thomas,
Cavan and Kerr, 2004) aims to reduce the consumption of carbonated drinks
in 615 children aged 7-11 years old via the delivery of a focused
educational programme on nutrition in schools. This study utilises a
cluster, randomised controlled experimental design. The actual procedure
is really rather complicated and lacks detail as in it leaves the reader
with more questions than answers and because of this, accurate replication
would likely be difficult. For example, it is not clear precisely how
much time and method of delivery was devoted to each component;
discouragement of ‘fizzy’ drinks, affirmation of a balanced healthy diet,
drinking water, presenting art, writing songs/raps outlining healthy
messages. And as a result of this it is impossible to identify which
aspects were actually effective and which were unnecessary. There is no
effort to detail exactly how these messages were delivered to the
participants apart from the considerations they made with regards to the
young age of the participants. The researchers tailored the study in many
ways to try to make the programme accessible to children. Firstly they
did this by keeping the message simple; ‘by decreasing sugar consumption
they would improve overall well-being’, to presumably help the children
understand the message though this is not explained and there is no
reference to previous research to justify this. Secondly, the study
incorporates a music competition for the participants to write a song or
rap with a healthy message and also produce and present pieces of their
own art. Once again there is no rationale for this but is probably used
to get the participants involved and thinking about the message and to
hold their attention. Clearly this would not be likely to be utilised in
a study using adults as participants and is more appropriate to childhood
intervention. The song writing and art presentations sound like very
appropriate methods for this intervention and demonstrate the importance
of the Lifespan approach when designing interventions to reach children
but unfortunately there is absolutely no indication of how these were
implemented or more importantly the impact that they might have had. It
would have been very interesting to read feedback of a qualitative nature
about any difficulties they had implementing this and whether the children
really became involved or not. In a perfect world one could imagine all
the children in a class competitively and enthusiastically painting and
singing and drinking water in their element but is that a realistic
approximation? After all, the interpretation of the results hinges on
these details.
On the positive side, the participants in the sample were
representative of the target population as this is aimed at
reducing/preventing childhood obesity and the size of the sample was large
enough for the number of measures and the effect size. The clusters (in
this case class) were randomly associated to either intervention or
control group and written consent was sought from both parents and
participants. It is claimed that each group were similar and equally
distributed in terms of age, sex and consumption of sweetened carbonated
drinks but there is no statistical test to confirm this. One problem with
the sampling, which the researchers point out, is that school s contained
classes both in the experimental and the control group and therefore it is
possible that ‘transfer of knowledge may have taken place outside the
classroom’ with participants discussing the different conditions amongst
themselves.
The measures taken are very empirically dubious. The participants
were asked to keep a three day diary both at the beginning and at the end
of the intervention (over one school year) and keep record of the drinks
that they consumed. It is doubtful whether this could be regarded an
appropriate method of collecting data considering the sample used. Is it
feasible to ask a 7 year old to keep an accurate diary indicative of the
complete beverages they have consumed? This is a poor method of
measurement with participants as young as this and indeed this was
reflected in the low number of completed diaries they received both at
baseline and the climax of the intervention. This resulted in a biased
result as the only data they received was from children motivated to keep
the diary and it is questionable how accurate these will have been in any
case. The anthropometric measurements were however a more appropriate
method of measurement. After the year long intervention the percentage of
obese/overweight participants had reduced in the intervention group
whereas the percentage had increased in the control group. This does
indeed indicate that the intervention did have a positive effect on the
participants’ health; it is just unclear precisely which elements are
responsible for this as the intervention aimed at healthy eating as well
and reducing carbonated drinks. Also, teachers in the intervention group
were asked to ‘encourage and reiterate the message in lessons’. This
alone could be responsible for the difference and is completely out of the
researchers’ control. Some teachers may encourage the health promoting
message frequently and others less so if at all. This study could be
described as being an amalgamation of multiple attempts to deliver the
health promotion message of reducing carbonated drinks and healthy eating
to children in various forms with flimsy description of precise procedures
but actually in the end it is reasonably successful. It has some
interesting methods of engaging the children and because it is multi-
faceted it seems to bombard the messages and the results seem to suggest
that the do influence the participants’ eating and drinking behaviour.
In line with the Lifespan approach, this study is important because
it is targeting children at a time when the instance of childhood obesity
is on the increase. By successfully equipping children with the ability
to avoid becoming obese, you automatically reduce incidence of future
adults becoming obese and techniques that will make a difference over the
lifespan. Magarey et al (2003) found that over 70% of obese children went
on to become obese adults. Therefore it is important to target children
with obesity prevention messages in order to prevent the next generation
being obese. This research targeted reduction of carbonated drinks as its
main message. This is interesting because children have fairly limited
control over what they eat and drink. This is because they are not old
enough to shop and cook independently and are therefore likely to be
eating similarly to their families or what is available at school. This
intervention target carbonated drinks as hey are arguably within a child’s
control of consumption. This is therefore highly appropriate along with
the general healthy eating message. This study does contribute to
existing research as it is set in the school setting and thus reaches its
targeted population. There are very few other school based obesity
interventions (Ebbeling, 2006)
Competing interests:
None declared
Competing interests: No competing interests