The research to date provides promising results indicating that, like the effects of policies on other public health problems such as tobacco use, policies can play an important role in decreasing SSB consumption and obesity rates among youth. In MS, studies have found lower youth SSB intake in school with policies directed at reduced access to vending machines, snack bars, and á la carte. Although there is less evidence for HS, access policies and improved meal practices still hold potential to significantly reduce the amount of SSB consumed. One critical insight from several studies is that reduced SSB consumption in schools is unlikely to be offset by increased SSB consumption outside of schools.
Studies also find that higher prices reduce overall SSB consumption. Although the effect of price on youth merits further study, research indicates that price increases will influence adult as well as youth purchases and will affect purchases inside and outside of school. They may have the greatest impact on youth who are overweight or from low-income families, but additional study is warranted.
Although several long term longitudinal studies have established the role of SSB and increased BMI, and school access, nutrition, and price policies have been shown to reduce SSB consumption, the direct estimate of these policies’ effects on BMI is less conclusive. Another line of research has found that, due to the lack of offset from consuming other foods or beverages, overall energy intake appears to decline by as much as and perhaps more than the decline in energy from SSB. The reduction in energy intake from even just one 8-oz. serving of SSB appears enough to have important effects on the prevalence of overweight and obese youth if policies are started at early ages and maintained.
Suggestions for future research.
The policy studies reviewed involve data collected before recent U.S. policies to reduce SSB consumption in schools. With access to LNED foods reduced since 2005 (40
), new studies will need to track SSB consumption inside and outside of schools and examine their effects.
While some studies consider more than one policy, they often do not explicitly consider how the effects of a policy may depend on the other policies in effect or how the effects vary by initial BMI, racial/ethnic group, and SES. Furthermore, the effects of policies may depend on exposure to past policies. For example, the effects of a MS program may depend on whether the child has been exposed to similar programs in ES, because those programs may have already affected their consumption habits and knowledge about nutrition. The effects of a specific policy may also vary over time. Research (79
) indicates that the likelihood of being overweight depends not only on parents, but also peers, suggesting that the effects of a policy may be amplified as its effects spread through social networks. On the other hand, the effects of a policy could diminish over time if food manufacturers adapt their marketing practices to maintain sales of SSB or if individuals adapt by consuming other LNED foods.
Other policies besides those considered above, such as limits on advertising, parent-student educational polices, or nonschool mass media policies, may also be used to reduce SSB intake. Although studies indicate that advertising affects LNED consumption (80
), research is needed on the population effect of advertising restrictions and public media campaigns on SSB consumption. In addition, further study is needed on how the effects of nutrition policies may be enhanced by physical activity policies.
Obesity is a complex problem, and solutions appropriate for complex problems are required. Better information is needed on how the effects of policies unfold over time as an individual ages and how changes in consumption patterns affect future dietary preferences and BMI trajectories. Empirical studies will need to use longitudinal data to consider these interrelationships over time. Alternatively, information from different studies may be combined in a modeling framework that explicitly considers the links from a policy change to reduced SSB consumption to lower BMI, as well as how policy effects may maintain or taper with age.
Because the effect of SSB has probably been studied more than other types of food and the links to BMI are relatively well understood, longitudinal studies and simulation models of the effects of SSB policies can also provide guidance to help better understand the effects of policies directed at other food types.