Effects of Soft Drink Consumption on Nutrition and Health

Effects of Soft Drink Consumption on Nutrition and Health:
A Systematic Review and Meta-Analysis
Lenny R. Vartanian, PhD, Marlene B. Schwartz, PhD, and
Kelly D. Brownell, PhD they displace other foods and beverages
and, hence, nutrients; whether they contribute to
diseases such as obesity and diabetes; and
whether soft drink marketing practices represent
commercial exploitation of children.3–5
The industry trade association in the
United States (the American Beverage Association,
formerly the National Soft Drink Association)
counters nutrition concerns with several
key points: (1) the science linking soft
drink consumption to negative health outcomes
is flawed or insufficient, (2) soft drinks
are a good source of hydration, (3) soft drink
sales in schools help education by providing
needed funding, (4) physical activity is more
important than food intake, and (5) it is unfair
to “pick on” soft drinks because there are
many causes of obesity and there are no
“good” or “bad” foods. Similar positions have
been taken by other trade associations such
as the British Soft Drinks Association and the
Australian Beverages Council.
Legislative and legal discussions focusing
on soft drink sales often take place on political
and philosophical grounds with scant attention
to existing science. Our objectives were to
review the available science, examine studies
that involved the use of a variety of methods,
and address whether soft drink consumption
is associated with increased energy intake, increased
body weight, displacement of nutrients,
and increased risk of chronic diseases.
METHODS
We focused on research investigating the
effects of sugar-sweetened beverages; diet
and artificially sweetened beverages are
noted only in certain cases for comparison
purposes. We conducted a computer search
through MEDLINE and PsycINFO using the
key terms “soft drink,” “soda,” and “sweetened
beverage.” We identified articles that assessed
the association of soft drink consumption with
4 primary outcomes (energy intake, body
weight, milk intake, and calcium intake) and
2 secondary outcomes (nutrition and health).
We identified additional articles by searching
each article’s reference section and the Web
of Science database. Finally, we contacted the
authors of each included article with a request
for unpublished or in-press work, and
we asked each author to forward our request
to other researchers who might have relevant
work. Our searches yielded a total of 88
articles that were included in the present
analysis.
There is a great deal of variability in research
methods in this literature. Studies
vary in their design (i.e., cross-sectional, longitudinal,
or experimental studies), sample
characteristics (e.g., male vs female, adults vs
children), and operational definitions of independent
and dependent variables. Because
such heterogeneity of research methods is
likely to produce heterogeneity of effect sizes
across studies (an effect size represents the
magnitude of the relationship between 2 variables),
we took 2 steps to assess the impact
of research method on outcome.
Initially, for each primary outcome (energy
intake, body weight, milk intake, and calcium
intake), we assessed the degree of heterogeneity
of effect sizes by testing the significance
of the Q statistic, which is the sum of the
squared deviations of each effect size from
the overall weighted mean effect size. We did
not assess the degree of heterogeneity for
Soft drink consumption has become a highly
visible and controversial public health and
public policy issue. Soft drinks are viewed by
many as a major contributor to obesity and
related health problems and have consequently
been targeted as a means to help curtail
the rising prevalence of obesity, particularly
among children. Soft drinks have been
banned from schools in Britain and France,
and in the United States, school systems as
large as those in Los Angeles, Philadelphia,
and Miami have banned or severely limited
soft drink sales. Many US states have considered
statewide bans or limits on soft drink
sales in schools, with California passing
such legislation in 2005. A key question is
whether actions taken to decrease soft drink
consumption are warranted given the available
science and whether decreasing population
consumption of soft drinks would benefit
public health.
The issue is not new. In 1942 the American
Medical Association mentioned soft
drinks specifically in a strong recommendation
to limit intake of added sugar.1 At that
time, annual US production of carbonated
soft drinks was 90 8-oz (240-mL) servings
per person; by 2000 this number had risen
to more than 600 servings.2 In the intervening
years, controversy arose over several fundamental
concerns: whether these beverages
lead to energy overconsumption; whether
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