Associations between state-level soda taxes and adolescent body mass index

An application of the augmented synthetic control method within a target trial framework: the case of the soda tax policy in California

BACKGROUND

Sugar-sweetened beverage (SSB) consumption is associated with increased obesity risk. One microeconomic intervention approach that has been studied is the increase of the cost of SSBs through SSB taxes. This study aims to apply the augmented synthetic control method (ASCM) within a target trial framework to estimate the impact of a 1-cent-per-ounce SSB tax on obesity prevalence in California.

METHODS

We used 2012-2020 data from the California Health Interview Survey (CHIS)'s AskCHIS Neighborhood Edition (AskCHIS NE) and the American Community Survey (ACS). The outcome of interest was obesity prevalence at the city level for people aged 18 and older. The estimated effect of the policy was calculated as the difference between the observed outcome in each soda tax city in the post-policy period and the predicted outcome in the synthetic controls in the post-policy period. The causal estimand of interest was the average treatment effect among the treated (ATT). We adjusted for sex, age, employment status, education, race/ethnicity, marital status, poverty, household median income, population size, and percentage of people who took public transportation to work.

RESULTS

Relative to not implementing a soda tax, the mean difference in obesity prevalence three years after the implementation of a soda tax was -5.5 (95%CI -34.9 to 21.1) percentage points (pp) in Berkeley, -1.7 (95%CI, -11.3 to 6.8) pp in Albany, -1.0 (95%CI, -6.5 to 4.3) pp in Oakland, and 2.6 (-11.0 to 16.8) pp in San Francisco. Overall, the mean difference in obesity prevalence was -1.4 (95%CI, -9.2 to 5.7) pp.

CONCLUSIONS

In this study, we illustrated the use of the augmented synthetic control methodology within a target trial framework with group-level longitudinal data. Our estimates of the impact of SSB tax policy on the obesity prevalence in California were imprecise.

Modeling and empirical evidence of the impact of implementation of sugar sweetened-beverages tax to reduce non-communicable diseases prevalence: a systematic review

Introduction

The surge in non-communicable diseases (NCDs) has been linked to excessive sugar-sweetened beverage (SSB) consumption. In response, the World Health Organization advocates for SSB taxes as a preventive measure. This study conducts a systematic literature review, encompassing simulation modeling and empirical evidence, to evaluate the effectiveness of SSB taxes in diminishing NCD prevalence.

Method

A systematic search from August 2002 to August 2022, utilizing databases like ScienceDirect, PubMed, Google Scholar, Wiley Online Library, Springer, and ResearchGate, identified 29 relevant articles worldwide following PRISMA 2020. The Critical Appraisal Skill Programme (CASP) 2018 tool was employed for economic evaluation.

Result

Among the selected articles, 22 utilized simulation models in group of countries such as South Africa, the US, the UK, Asia (Philippines, India, Indonesia, Thailand), Australia, and Europe (Germany), while seven were based on US and UK evidence. Simulation modeling consistently demonstrated that SSB taxes significantly reduced NCD incidence, prevalence, and mortality, also bolstering government revenue. Tax rates in simulations ranged from 10 to 25%. However, empirical evidence indicated a limited impact, primarily due to low tax rates. Notably, a UK-specific tax led to a 2.7% reduction in SSB sugar purchases and 40.2% higher purchases of no-levy drinks.

Discussion

The findings suggest that while simulation models demonstrate the potential effectiveness of SSB taxes in reducing NCDs, empirical evidence reveals there is no significant effect of the SSB tax, Based on the study conducted in this study, the SSB tax is not effective in reducing the prevalence of NCDs due to consumer preferences that have not changed. , likely due to the implementation of lower tax rates and failure to fulfill the assumption of subtitution product, physical activity, and so on. The study highlights that SSB tax is not effective in reducing the prevalence of NCDs due to consumer preference that have not change. Multi-actions are needed to support the sustainability of the implementation of the SSB tax, including education and promotion of healthy lifestyles and encouragement to reformulate SSB products by industry.

Impact of soda tax on beverage price, sale, purchase, and consumption in the US: a systematic review and meta-analysis of natural experiments

Background

As a primary source of added sugars in the US diet, sugar-sweetened beverage (SSB) consumption is presumed to contribute to obesity prevalence and poor oral health. We systematically synthesized and quantified evidence from US-based natural experiments concerning the impact of SSB taxes on beverage prices, sales, purchases, and consumption.

Methods

A keyword and reference search was performed in PubMed, Web of Science, Cochrane Library, Scopus, and EconLit from the inception of an electronic bibliographic database to Oct 31, 2022. Meta-analysis was conducted to estimate the pooled effect of soda taxes on SSB consumption, prices, passthrough rate, and purchases.

Results

Twenty-six natural experiments, all adopting a difference-in-differences approach, were included. Studies assessed soda taxes in Berkeley, Oakland, and San Francisco in California, Philadelphia in Pennsylvania, Boulder in Colorado, Seattle in Washington, and Cook County in Illinois. Tax rates ranged from 1 to 2 ¢/oz. The imposition of the soda tax was associated with a 1.06 ¢/oz. (95% confidence interval [CI] = 0.90, 1.22) increase in SSB prices and a 27.3% (95% CI = 19.3, 35.4%) decrease in SSB purchases. The soda tax passthrough rate was 79.7% (95% CI = 65.8, 93.6%). A 1 ¢/oz. increase in soda tax rate was associated with increased prices of SSBs by 0.84 ¢/oz (95% CI = 0.33, 1.35).

Conclusion

Soda taxes could be effective policy leverage to nudge people toward purchasing and consuming fewer SSBs. Future research should examine evidence-based classifications of SSBs, targeted use of revenues generated by taxes to reduce health and income disparities, and the feasibility of redesigning the soda tax to improve efficiency.

Associations between trajectories of obesity prevalence in English primary school children and the UK soft drinks industry levy: An interrupted time series analysis of surveillance data

BACKGROUND

Sugar-sweetened beverages (SSBs) are the primary source of dietary added sugars in children, with high consumption commonly observed in more deprived areas where obesity prevalence is also highest. Associations between SSB consumption and obesity in children have been widely reported. In March 2016, a two-tier soft drinks industry levy (SDIL) on drinks manufacturers to encourage reformulation of SSBs in the United Kingdom was announced and then implemented in April 2018. We examined trajectories in the prevalence of obesity at ages 4 to 5 years and 10 to 11 years, 19 months after the implementation of SDIL, overall and by sex and deprivation.

METHODS AND FINDINGS

Data were from the National Child Measurement Programme and included annual repeat cross-sectional measurement of over 1 million children in reception (4 to 5 years old) and year 6 (10 to 11 years old) in state-maintained English primary schools. Interrupted time series (ITS) analysis of monthly obesity prevalence data from September 2013 to November 2019 was used to estimate absolute and relative changes in obesity prevalence compared to a counterfactual (adjusted for temporal variations in obesity prevalence) estimated from the trend prior to SDIL announcement. Differences between observed and counterfactual estimates were examined in November 2019 by age (reception or year 6) and additionally by sex and deprivation quintile. In year 6 girls, there was an overall absolute reduction in obesity prevalence (defined as >95th centile on the UK90 growth charts) of 1.6 percentage points (PPs) (95% confidence interval (CI): 1.1, 2.1), with greatest reductions in the two most deprived quintiles (e.g., there was an absolute reduction of 2.4 PP (95% CI: 1.6, 3.2) in prevalence of obesity in the most deprived quintile). In year 6 boys, there was no change in obesity prevalence, except in the least deprived quintile where there was a 1.6-PP (95% CI: 0.7, 2.5) absolute increase. In reception children, relative to the counterfactual, there were no overall changes in obesity prevalence in boys (0.5 PP (95% CI: 1.0, -0.1)) or girls (0.2 PP (95% CI: 0.8, -0.3)). This study is limited by use of index of multiple deprivation of the school attended to assess individual socioeconomic disadvantage. ITS analyses are vulnerable to unidentified cointerventions and time-varying confounding, neither of which we can rule out.

CONCLUSIONS

Our results suggest that the SDIL was associated with decreased prevalence of obesity in year 6 girls, with the greatest differences in those living in the most deprived areas. Additional strategies beyond SSB taxation will be needed to reduce obesity prevalence overall, and particularly in older boys and younger children.

TRIAL REGISTRATION

ISRCTN18042742.

Effects of public policies in the prevention of cardiovascular diseases: a systematic review of global literature

OBJECTIVES

Given the growing interest worldwide in applying public policies to improve human health, we undertook a systematic review of studies investigating whether public policies targeting unhealthy products could reduce cardiovascular diseases.

STUDY DESIGN

This study was a systematic review of the literature.

METHODS

We searched research studies published in 2000-2020 from major databases, including MEDLINE and Embase. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and narratively synthesized the studies based on vote counting and direction of the intervention effect.

RESULTS

Ninety-eight studies, mostly from high-income countries, met the inclusion criteria. Most studies were on public policies targeting sugar-sweetened beverages and tobacco, followed by alcohol, sugar, salt, and junk foods. Overall, many reported that several fiscal, regulatory, and educational policies generated beneficial effects of reducing the diseases. Those studies that reported no or limited effects highlighted several sociodemographic and health risk characteristics and design and implementation aspects of the policy interventions as factors limiting the policy effects; most of these are modifiable with appropriate policy interventions. For instance, low magnitude of tax, substitution with other unhealthy products, firms' competitive response strategies, pre-existence of smoking bans, incremental enactment of smoking regulations, degree of enforcement, and various sociocultural factors minimized the effects of the policies.

CONCLUSION

The literature supports a growing consensus on the beneficial effects of public policy for improving human health. The design and implementation of public policies must address various impeding factors and incorporate appropriate remedial measures. Further research is needed from low- and middle-income countries and on whether and how multiple policy instruments work in tandem.

Fructose Intake, Hypertension and Cardiometabolic Risk Factors in Children and Adolescents: From Pathophysiology to Clinical Aspects. A Narrative Review

Arterial hypertension, dyslipidemia, alterations in glucose metabolism and fatty liver, either alone or in association, are frequently observed in obese children and may seriously jeopardize their health. For obesity to develop, an excessive intake of energy-bearing macronutrients is required; however, ample evidence suggests that fructose may promote the development of obesity and/or metabolic alterations, independently of its energy intake. Fructose consumption is particularly high among children, because they do not have the perception, and more importantly, neither do their parents, that high fructose intake is potentially dangerous. In fact, while this sugar is erroneously viewed favorably as a natural nutrient, its excessive intake can actually cause adverse cardio-metabolic alterations. Fructose induces the release of pro-inflammatory cytokines, and reduces the production of anti-atherosclerotic cytokines, such as adiponectin. Furthermore, by interacting with hunger and satiety control systems, particularly by inducing leptin resistance, it leads to increased caloric intake. Fructose, directly or through its metabolites, promotes the development of obesity, arterial hypertension, dyslipidemia, glucose intolerance and fatty liver. This review aims to highlight the mechanisms by which the early and excessive consumption of fructose may contribute to the development of a variety of cardiometabolic risk factors in children, thus representing a potential danger to their health. It will also describe the main clinical trials performed in children and adolescents that have evaluated the clinical effects of excessive intake of fructose-containing drinks and food, with particular attention to the effects on blood pressure. Finally, we will discuss the effectiveness of measures that can be taken to reduce the intake of this sugar.

Changes in Weight-Related Outcomes Among Adolescents Following Consumer Price Increases of Taxed Sugar-Sweetened Beverages

IMPORTANCE

Following the implementation of a tax on sugar-sweetened beverages (SSBs) in Mexico in 2014, SSB prices increased by about 10% on average, but differently across cities. It remains unclear how observed SSB price changes are associated with adolescent weight-related outcomes.

OBJECTIVE

To compare weight-related outcomes among adolescents living in cities with differential SSB price changes before and after the SSB tax was implemented in Mexico.

DESIGN, SETTING, AND PARTICIPANTS

Associations between differential SSB price changes and changes in weight-related outcomes were examined overall and by sex among 12 654 adolescents aged 10 to 18 years born between 1999 and 2002 living in 39 cities in Mexico. Multivariate regressions with individual fixed effects were applied on longitudinal individual-level yearly clinical data (height and weight) from 2012 to 2017 collected by the Instituto Mexicano del Seguro Social (IMSS) and merged with city-level SSB price data from 2011 to 2016 collected by the National Institute of Statistics and Geography (INEGI). Data were analyzed from July 2018 to July 2021.

EXPOSURES

Yearly city-level changes in SSB prices between 2011 and 2016.

MAIN OUTCOMES AND MEASURES

Age- and sex-specific body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) percentile and indicator for overweight or obesity if BMI was at or above the 85th percentile.

RESULTS

Before 2014, 46% of 12 654 adolescents (6850 girls and 5804 boys) included in this study had obesity or overweight. The mean (SD) age was 11.38 (1.08) years. Among girls, a 10% SSB price increase was associated with a 1.3 percentage point absolute decrease (95% CI, -2.19 to -0.36; P = .008) or a 3% relative decrease in overweight or obesity prevalence within 2 years of a price change. For girls with BMI at or above the 75th percentile pretax, this price increase was associated with a 0.59 lower BMI percentile (95% CI, -1.08 to -0.10; P = .02) or a 0.67% relative decrease. Improved outcomes for girls were observed in cities where price increases were greater than 10% after the tax. No such associations were observed for boys.

CONCLUSIONS AND RELEVANCE

In this study, increased SSB prices were associated with decreased overweight or obesity prevalence among girls but not among boys. Improvements in outcomes were small, and mostly observed for girls with heavier weight and in cities where price increases after the tax were greater than 10%.

Bittersweet: How prices of sugar-rich foods contribute to the diet-related disease epidemic in Mexico

I provide new evidence on how price changes of nutritionally similar foods, such as those rich in sugar or fats, change obesity and diet-related diseases in the context of Mexico between 1996-2010. I merge a bar-code level price dataset with product-specific nutritional composition to two datasets with health outcomes: state-level administrative and nationally representative individual-level panel data. Exploiting within-city variation in prices using fixed effects models, I show that decreased prices of sugar-rich foods increase obesity, type 2 diabetes, and hypertension prevalence; yet the prices of foods rich in other nutrients do not. Health responses to price changes are the largest for those abdominally obese or at the highest risk for chronic disease. The association between prices of sugary foods and chronic disease is meaningful: I estimate that in Mexico, price reductions of sugary foods explain roughly 15 percent of the rise in obesity and diabetes during the 15-year study period.

Taxing sugar-sweetened beverages as a policy to reduce overweight and obesity in countries of different income classifications: a systematic review

OBJECTIVE

To evaluate the potential impact of sugar-sweetened beverage (SSB) taxes on overweight and obesity prevalence in countries of different income classifications.

DESIGN

Systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO number CRD42020161612). Five databases (Cochrane Library, Embase, LILACS (via Virtual Health Library) and MEDLINE (via PubMed), and Web of Science were searched, from January 2009 to December 2019. Articles that reported changes in purchases, sales, intake, body weight, BMI, overweight and/or obesity prevalence due to a tax on or price change in SSB were included.

SETTING

Studies conducted in countries of different income classifications.

PARTICIPANTS

The search yielded 8349 articles of which 21 met inclusion criteria.

RESULTS

Among the sixteen studies selected, only two did not show that consumption, sales and purchase decreased as the price of SSB increased. In eight of the thirteen studies selected, a positive effect of an SSB tax on decreasing overweight and obesity prevalence was expected. It is estimated that a 20 % taxation on SSB would result in a greater decrease in the prevalence of overweight and obesity compared to a 10 % rate. Studies with no significant effect of taxing on sales, purchases, consumption and prevalence of obesity were from high-income countries, while significant effects of taxing on reducing purchase, consumption and/or obesity prevalence were found in studies from upper-middle- and middle-income countries.

CONCLUSION

A high SSB tax might be an effective fiscal policy to decrease purchase and consumption of SSB and reduce overweight/obesity prevalence, especially if the tax were specific for beverage volume.

The effect of Public Health/Pediatric Obesity interventions on socioeconomic inequalities in childhood obesity: A scoping review

Childhood obesity has a strong social gradient. This scoping review aims to synthesize the evidence on the impact on inequalities of non-targeted interventions to reduce the prevalence of childhood and adolescent obesity in high-income countries. We updated a review by Hillier-Brown, searching up to 31 December 2017 on MEDLINE, Embase, The Cochrane Library, CINAHL, and PsycINFO, with no limitations on study design. Fifty-eight studies describing 51 interventions were included: 31 randomized clinical trials and 27 non-randomized trials, with sample sizes from 67 to 2,700,880 subjects. The majority were implemented in the school setting at a community level; the others were in health services or general population setting and targeting individuals or the system. Twenty-nine interventions proved to be effective overall; seven others had an effect only in a subgroup, while 15 proved not to be effective. All types of included interventions can increase inequalities. Moreover, some interventions had opposite effects based on the socioeconomic characteristics. Any kind of intervention can reduce equity. Consequences are difficult to predict based on intervention construct. Complex interventions acting on multiple targets, settings, and risk factors are more effective and have a lower risk of increasing inequalities.

Insights on the Influence of Sugar Taxes on Obesity Prevention Efforts

PURPOSE OF REVIEW

This review will present the latest evidence on the impacts of sugar taxes on obesity with a focus on sugar-sweetened beverages (SSB).

RECENT FINDINGS

Evidence of direct impacts of SSB taxation policies on obesity prevalence continues to be limited. Natural experiments involving SSB taxation policies implemented in Mexico and Berkley, CA, indicate that this type of intervention alters beverage consumption patterns. Naturalistic evidence in combination with modeling studies suggests that SSB taxation is a viable anti-obesity policy. However, researchers and public health practitioners need to be vigilant of industry tactics to curtail SSB lowering efforts. To maximize the impacts of SSB taxation, it should be combined with interventions that increase access to non-sweetened beverages, educate consumers about alternative healthy beverages, and explore taxation of other non-nutritive foods and beverages. Furthermore, both intended and unintended consequences of interventions should be closely monitored.

The price of ultra-processed foods and beverages and adult body weight: Evidence from U.S. veterans

The consumption of ultra-processed foods in the U.S. and globally has increased and is associated with lower diet quality, higher energy intake, higher body weight, and poorer health outcomes. This study drew on individual-level data on measured height and weight from U.S. Department of Veterans Affairs medical records for adults aged 20 to 64 from 2009 through 2014 linked to food and beverage price data from the Council for Community and Economic Research to examine the association between the price of ultra-processed foods and beverages and adult body mass index (BMI). We estimated geographic fixed effects models to control for unobserved heterogeneity of prices. We estimated separate models for men and women and we assessed differences in price sensitivity across subpopulations by socioeconomic status (SES). The results showed that a one-dollar increase in the price of ultra-processed foods and beverages was associated with 0.08 lower BMI units for men (p ≤ 0.05) (price elasticity of BMI of -0.01) and 0.14 lower BMI units for women (p ≤ 0.10) (price elasticity of BMI of -0.02). Higher prices of ultra-processed foods and beverages were associated with lower BMI among low-SES men (price elasticity of BMI of -0.02) and low-SES women (price elasticity of BMI of -0.07) but no statistically significant associations were found for middle- or high-SES men or women. Robustness checks based on the estimation of an individual-level fixed effects model found a consistent but smaller association between the price of ultra-processed foods and beverages and BMI among women (price elasticity of BMI of -0.01) with a relatively larger association for low-SES women (price elasticity of BMI of -0.04) but revealed no association for men highlighting the importance of accounting for individual-level unobserved heterogeneity.

Efficacy of population-wide diabetes and obesity prevention programs: An overview of systematic reviews on proximal, intermediate, and distal outcomes and a meta-analysis of impact on BMI

We conducted an overview of systematic reviews and a meta-analysis of the impact on body mass index (BMI) of primary studies of population-wide obesity and diabetes prevention programs, in order to evaluate their efficacy. We searched eight databases for reviews of population-level programs reporting effect on diet, physical activity, BMI, or prevalence of obesity/overweight or type 2 diabetes mellitus (T2DM). Meta-analysis of primary studies within reviews reporting effect on BMI. Interventions were categorized using ANGELO framework and quality assessment using AMSTAR. Fifty-three systematic reviews were included. Primary studies were largely natural experiments or cross-sectional studies of national data. Increased price of sugar-sweetened beverages (SSBs) and fast food, decreased price of fruit and vegetables, food labelling, and grocery store interventions were associated with positive effects on diet. Park and playground renovations and point-of-choice prompts to increase stair use were associated with positive effects on physical activity. Increased price of SSBs, menu labelling, grocery store interventions, and multicomponent interventions were associated with small reductions in BMI. There was insufficient evidence of impact of any interventions on the prevalence of overweight, obesity, or T2DM. We have identified a promising suite of population-wide actions to improve diet, increase physical activity, and reduce BMI. Impact on subsequent incidence of T2DM remains speculative.

Effects of Contextual Economic Factors on Childhood Obesity

OBJECTIVES

To examine the association between changes in contextual economic factors on childhood obesity in the US.

METHODS

We combined data from 2003, 2007, and 2011/2012 National Surveys of Children's Health for 129,781 children aged 10-17 with 27 state-level variables capturing general economic conditions, labor supply, and the monetary or time costs of calorie intake, physical activity, and cigarette smoking. We employed regression models controlling for demographic factors and state and year fixed effects. We also examined heterogeneity in economic effects by household income.

RESULTS

Obesity risk increased with workforce proportion in blue-collar occupations, urban sprawl, female labor force participation, and number of convenience stores but declined with median household income, smoking ban in restaurants, and full service restaurants per capita. Most effects were specific to low income households, except for density of supercenters/warehouse clubs which was significantly associated with higher overweight/obesity risk only in higher income households.

CONCLUSIONS FOR PRACTICE

Changes in state-level economic factors related to labor supply and monetary or time cost of calorie intake may affect childhood obesity especially for children in low-income households. Policymakers should consider these effects when designing programs aimed at reducing childhood obesity.

The Legacy of 1987 Boreali v. Axelrod: Board of Health Rule-Making Under Siege

We explore how a 1987 New York State court decision—Boreali v. Axelrod—affected public health rule-making nationally and, with considerable impact, locally in New York City (NYC).

We discuss the history of the origin of the NYC Board of Health (BOH), and establish that legislatures can be challenging venues in which to enact public health–related laws. We describe how, as the NYC Department of Health and Mental Hygiene began to tackle modern public health problems (e.g., chronic diseases caused by food and tobacco), the regulatory power of its BOH was challenged.

In an era when industry funds political causes and candidates, the weakening of the independence of rule-making boards of health, such as the NYC BOH, might result in illness and death.

Taxation of sugar sweetened beverages and unhealthy foods: a qualitative study of key opinion leaders' views

Background

Fiscal policies to fight obesity such as taxation of unhealthy foods or sugar-sweetened beverages (SSBs) have gained considerable attention in recent years. Many studies modelling the impact of various magnitudes of taxes on SSB purchasing and their potential effects on various health outcomes have been published; however, legislation and implementation of such taxes have encountered many obstacles in the countries that have implemented them to date. We investigated the perceptions and views of key opinion leaders, policy makers and various other Israeli stakeholders on taxation of SSBs and unhealthy snacks. We also evaluated the challenges and barriers that may be expected for initiating such a policy.

Methods

A qualitative study based on 39 in-depth interviews with Israeli stakeholders in the fields of health, nutrition, economics, public advocacy and policymaking.

Results

All stakeholders viewed obesity as a combined societal and personal issue that should be under government responsibility. Only stakeholders from economic sectors thought that taxation of SSBs and unhealthy snacks would reduce their consumption, while the prevailing notion among non-economists was that such a tax would not be acceptable because the higher price would not decrease consumption. Concerns were raised that the tax would mostly affect individuals from low socioeconomic backgrounds. Some of the stakeholders indicated that they would support such a tax only if its revenue would be directed to specific causes such as health-promoting plans. Potential barriers to taxation include: opposition of various sectors, technical and bureaucratic obstacles impeding tax implementation, difficulties in defining which products to tax, and opposition of the treasury to earmark tax revenue for health education.

Conclusions

Taxation should be a part of a multipronged strategy rather than a sole measure for fighting obesity. Dedicating tax revenues to specific predefined causes should be considered, particularly towards health promotion activities, obesity treatment and prevention, education, and subsidies of healthy food.

Methods for Evaluating Natural Experiments in Obesity: A Systematic Review

BACKGROUND

Given the obesity pandemic, rigorous methodological approaches, including natural experiments, are needed.

PURPOSE

To identify studies that report effects of programs, policies, or built environment changes on obesity prevention and control and to describe their methods.

DATA SOURCES

PubMed, CINAHL, PsycINFO, and EconLit (January 2000 to August 2017).

STUDY SELECTION

Natural experiments and experimental studies evaluating a program, policy, or built environment change in U.S. or non-U.S. populations by using measures of obesity or obesity-related health behaviors.

DATA EXTRACTION

2 reviewers serially extracted data on study design, population characteristics, data sources and linkages, measures, and analytic methods and independently evaluated risk of bias.

DATA SYNTHESIS

294 studies (188 U.S., 106 non-U.S.) were identified, including 156 natural experiments (53%), 118 experimental studies (40%), and 20 (7%) with unclear study design. Studies used 106 (71 U.S., 35 non-U.S.) data systems; 37% of the U.S. data systems were linked to another data source. For outcomes, 112 studies reported childhood weight and 32 adult weight; 152 had physical activity and 148 had dietary measures. For analysis, natural experiments most commonly used cross-sectional comparisons of exposed and unexposed groups (n = 55 [35%]). Most natural experiments had a high risk of bias, and 63% had weak handling of withdrawals and dropouts.

LIMITATION

Outcomes restricted to obesity measures and health behaviors; inconsistent or unclear descriptions of natural experiment designs; and imperfect methods for assessing risk of bias in natural experiments.

CONCLUSION

Many methodologically diverse natural experiments and experimental studies were identified that reported effects of U.S. and non-U.S. programs, policies, or built environment changes on obesity prevention and control. The findings reinforce the need for methodological and analytic advances that would strengthen evaluations of obesity prevention and control initiatives.

PRIMARY FUNDING SOURCE

National Institutes of Health, Office of Disease Prevention, and Agency for Healthcare Research and Quality. (PROSPERO: CRD42017055750).

Sugar-Sweetened Beverage, Obesity, and Type 2 Diabetes in Children and Adolescents: Policies, Taxation, and Programs

PURPOSE OF REVIEW

Obesity has grown at an alarming rate in children and adolescents. Concurrently, consumption on sugar-sweetened beverages (SSBs) also rose significantly. This review provides an overview of obesity and type 2 diabetes mellitus (T2DM) related to SSBs and current policies restricting SSBs in schools, school-based interventions, and taxation on reducing SSB intake and obesity. We also discuss challenges of and future steps for these initiatives.

RECENT FINDINGS

Clinical and epidemiological studies suggest a strong association between SSB intake and obesity and T2DM. School food policies have been initiated at federal, state, and local levels. School-based interventions have shown positive effects on SSB intake and obesity reduction. Taxation on SSBs is promising in combating obesity and in generating revenue. Challenges towards compliance and implementation of the policies and programs exist. The relationship between SSB and obesity and T2DM is a complex problem which requires comprehensive solutions. Continued efforts in restricting SSBs in schools are needed. Intervention programs should be tailored to age, gender, language, and culture and involve participation from families and local communities. Taxation can reduce SSB consumption by direct economic incentive, earmarking revenues to support healthy foods, and sending negative message. However, a higher tax rate may be necessary to have a measurable effect on weight.

Funding quality pre-kindergarten slots with Philadelphia's new 'sugary drink tax': simulating effects of using an excise tax to address a social determinant of health

OBJECTIVE

Philadelphia passed a 1·5-cent-per-ounce sweetened beverage tax (SBT). Revenue will fund 10 000 quality pre-kindergarten slots for poor children. It is imperative to understand how revenue from SBT can be used to fund programmes to address education and other social determinants of health. The objective of the present study was to simulate quality pre-kindergarten attendance, educational achievement and sugar-sweetened beverage (SSB) consumption among Philadelphia children and adolescents under six intervention scenarios: (i) no intervention; (ii) 10 000 additional quality pre-kindergarten slots; (iii) a 1·5-cent-per-ounce SBT; (iv) expanded pre-kindergarten and 1·5-cent-per-ounce SBT; (v) a 3-cent-per-ounce SBT; and (vi) expanded pre-kindergarten and 3-cent-per-ounce SBT.

DESIGN

We used an agent-based model to estimate pre-kindergarten enrolment, educational achievement and SSB consumption under the six policy scenarios. We identified key parameters in the model from the published literature and secondary analyses of the Panel Study of Income Dynamics - Child Development Supplement.

SETTING

Philadelphia, Pennsylvania, USA.

SUBJECTS

Philadelphia children and adolescents aged 4-18 years.

RESULTS

A 1·5-cents-per-ounce tax would reduce SSB consumption by 1·3 drinks/week among Philadelphia children and adolescents relative to no intervention, with larger effects among children below the poverty level. Quality pre-kindergarten expansion magnifies the effect of the SBT by 8 %, but has the largest effect on moderate-income children just above the poverty level. The SBT and quality pre-kindergarten programme each reduce SSB consumption, but primarily benefit different children and adolescents.

CONCLUSIONS

Pairing an excise tax with a complementary programme to improve a social determinant of health represents a progressive strategy to combat obesity, a disease regressive in its social patterning.

Policy lessons from health taxes: a systematic review of empirical studies

BACKGROUND

Taxes on alcohol and tobacco have long been an important means of raising revenues for public spending in many countries but there is increasing interest in using taxes on these, and other unhealthy products, to achieve public health goals. We present a systematic review of the research on health taxes, and aim to generate insights into how such taxes can: (i) reduce consumption of targeted products and related harms; (ii) generate revenues for health objectives and distribute the tax burden across income groups in an efficient and equitable manner; and (iii) be made politically sustainable.

METHODS

Six scientific and four grey-literature databases were searched for empirical studies of 'health taxes' - defined as those intended to increase the costs of manufacturing, distributing, retailing and/or consuming health-damaging products. Since reviews already exist of the evidence relating to traditional alcohol and tobacco excise taxes, we focus on other taxes such as taxes on retailers and manufacturers of unhealthy products, and consumer taxes targeting unhealthy foods, such as sugar-sweetened beverages.

RESULTS

Ninety-one peer-reviewed and 11 grey-literature studies met our inclusion criteria. The review highlights a recent, rapid rise in research in this area, most of which focuses on high-income countries and on taxes on food products or nutrients. Findings demonstrate that high tax rates on sugar-sweetened beverages are likely to have a positive impact on health behaviours and outcomes, and, while taxes on products reduce demand, they add to fiscal revenues. Common concerns about health taxes are also discussed.

CONCLUSIONS

If the primary policy goal of a health tax is to reduce consumption of unhealthy products, then evidence supports the implementation of taxes that increase the price of products by 20% or more. However, where taxes are effective in changing health behaviours, the predictability of the revenue stream is reduced. Hence, policy actors need to be clear about the primary goal of any health tax and frame the tax accordingly - not doing so leaves taxes vulnerable to hostile lobbying. Conversely, earmarking health taxes for health spending tends to increase public support so long as policymakers follow through on specified spending commitments.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42016048603.

Economics and obesity policy

This paper elucidates the challenges surrounding the economics of some popular obesity-related policy proposals. Solid economic justifications for anti-obesity policies are often lacking, and evidence suggests policies like fat and soda taxes or restrictions on food stamp spending are unlikely to substantively affect obesity prevalence. In short, many of the same factors that make obesity such a complicated and multifaceted issue extend to the economic analysis of public health policies.

Partner Influence in Diet and Exercise Behaviors: Testing Behavior Modeling, Social Control, and Normative Body Size

Previous research has documented social contagion in obesity and related health behaviors, but less is known about the social processes underlying these patterns. Focusing on married or cohabitating couples, we simultaneously explore three potential social mechanisms influencing obesity: normative body size, social control, and behavior modeling. We analyze the association between partner characteristics and the obesity-related health behaviors of focal respondents, comparing the effects of partners' body type, partners' attempts to manage respondents' eating behaviors, and partners' own health behaviors on respondents' health behaviors (physical activity, fruit and vegetable consumption, and fast food consumption). Data on 215 partners are extracted from a larger study of social mechanisms of obesity in family and community contexts conducted in 2011 in the United States. Negative binomial regression models indicate that partner behavior is significantly related to respondent behavior (p < .001), net of controls. These results are suggestive of a behavior modeling mechanism in obesity-related patterns of consumption and physical activity. In contrast, we find little support for the influence of normative body size or partner social control in this sample, though generalizations about the relevance of these processes may be inappropriate. These results underscore the importance of policies and interventions that target dyads and social groups, suggesting that adoption of exercise or diet modifications in one individual is likely to spread to others, creating a social environment characterized by mutual reinforcement of healthy behavior.

Can policy ameliorate socioeconomic inequities in obesity and obesity-related behaviours? A systematic review of the impact of universal policies on adults and children

This systematic review examined the impact of universal policies on socioeconomic inequities in obesity, dietary and physical activity behaviours among adults and children. PRISMA-Equity guidelines were followed. Database searches spanned from 2004 to August 2015. Eligible studies assessed the impact of universal policies on anthropometric, dietary or physical activity-related outcomes in adults or children according to socioeconomic position. Thirty-six studies were included. Policies were classified as agentic, agento-structural or structural, and their impact on inequities was rated as positive, neutral, negative or mixed according to the dominant associations observed. Most policies had neutral impacts on obesity-related inequities regardless of whether they were agentic (60% neutral), agento-structural (68% neutral) or structural (67% neutral). The proportion of positive impacts was similar across policy types (10% agentic, 18% agento-structural and 11% structural), with some differences for negative impacts (30% agentic, 14% agento-structural and 22% structural). The majority of associations remained neutral when stratified by participant population, implementation level and socioeconomic position measures and by anthropometric and behavioural outcomes. Fiscal measures had consistently neutral or positive impacts on inequities. Findings suggest an important role for policy in addressing obesity in an equitable manner and strengthen the case for implementing a broad complement of policies spanning the agency-structure continuum.

Cardiovascular diseases in mega-countries: the challenges of the nutrition, physical activity and epidemiologic transitions, and the double burden of disease

PURPOSE OF REVIEW

There are today 11 mega-countries with more than 100 million inhabitants. Together these countries represent more than 60% of the world's population. All are facing noncommunicable chronic disease (NCD) epidemic where high cholesterol, obesity, diabetes, and cardiovascular diseases are becoming the main public health concerns. Most of these countries are facing the double burden of malnutrition where undernutrition and obesity coexist, increasing the complexity for policy design and implementation. The purpose of this study is to describe diverse sociodemographic characteristics of these countries and the challenges for prevention and control in the context of the nutrition transition.

RECENT FINDINGS

Mega-countries are mostly low or middle-income and are facing important epidemiologic, nutrition, and physical activity transitions because of changes in food systems and unhealthy lifestyles. NCDs are responsible of two-thirds of the 57 million global deaths annually. Approximately, 80% of these are in low and middle-income countries. Only developed countries have been able to reduce mortality rates attributable to recognized risk factors for NCDs, in particular high cholesterol and blood pressure.

SUMMARY

Mega-countries share common characteristics such as complex bureaucracies, internal ethnic, cultural and socioeconomic heterogeneity, and complexities to implement effective health promotion and education policies across population. Priorities for action must be identified and successful lessons and experiences should be carefully analyzed and replicated.

Impact of sugars and sugar taxation on body weight control: A comprehensive literature review

OBJECTIVE

To conduct a comprehensive literature review in the field of added-sugar consumption on weight gain including the effect of fructose-containing caloric sweeteners and sugar taxation.

METHODS

A search of three databases was conducted in the time period from the inception of the databases to August 2015. Sensitive search strategies were used in order to retrieve systematic reviews (SR) of fructose, sucrose, or sugar-sweetened beverages (SSBs) on weight gain and metabolic adverse effects, conducted on humans and written in English, Spanish, or French. In addition, a review about SSB taxation and weight outcomes was conducted.

RESULTS

The search yielded 24 SRs about SSBs and obesity, 23 SRs on fructose or SSBs and metabolic adverse effects, and 24 studies about SSB taxation and weight control.

CONCLUSIONS

The majority of SRs, especially the most recent ones, with the highest quality and without any disclosed conflict of interest, suggested that the consumption of SSBs is a risk factor for obesity. The effect of fructose-containing caloric sweeteners, on weight gain is mediated by overconsumption of beverages with these sweeteners, leading to an extra provision of energy intake. The tax tool alone on added sugars appears insufficient to curb the obesity epidemic, but it needs to be included in a multicomponent structural strategy.

The impact of a tax on sugar-sweetened beverages according to socio-economic position: a systematic review of the evidence

Objective

A tax on sugar-sweetened beverages (SSB) has been proposed to address population weight gain but the effect across socio-economic position (SEP) is unclear. The current study aimed to clarify the differential impact(s) of SSB taxes on beverage purchases and consumption, weight outcomes and the amount paid in SSB taxes according to SEP.

Design

Databases (OVID and EMBASE) and grey literature were systematically searched in June 2015 to identify studies that examined effects of an SSB price increase on beverage purchases or consumption, weight outcomes or the amount paid in tax across SEP, within high-income countries.

Results

Of the eleven included articles, three study types were identified: (i) those that examined the association between variation in SSB taxes and SSB consumption and/or body weight (n 3); (ii) price elasticity estimation of SSB demand (n 1); and (iii) modelling of hypothetical SSB taxes by combining price elasticity estimates with population SEP-specific beverage consumption, energy intake or body weight (n 7). Few studies statistically tested differences in outcomes between SEP groups. Nevertheless, of the seven studies that reported on changes in weight outcomes for the total population following an increase in SSB price, all reported either similar reductions in weight across SEP groups or greater reductions for lower compared with higher SEP groups. All studies that examined the average household amount paid in tax (n 5) reported that an SSB tax would be regressive, but with small differences between higher- and lower-income households (0·10–1·0 % and 0·03 %–0·60 % of annual household income paid in SSB tax for low- and high-income households, respectively).

Conclusions

Based on the available evidence, a tax on SSB will deliver similar population weight benefits across socio-economic strata or greater benefits for lower SEP groups. An SSB tax is shown to be consistently financially regressive, but to a small degree.

A Qualitative Study of Adolescent Views of Sugar-Sweetened Beverage Taxes, Michigan, 2014

Introduction

We conducted a qualitative study to gather information on adolescent views of how a 20% tax on sugar-sweetened beverages (SSBs) would affect adolescents’ consumption of SSBs. The role of habit in consumption of SSBs was also explored.

Methods

We held 3 focus groups with students from various racial/ethnic groups (N = 22) in grades 6 through 8 at a Michigan middle school. Data on demographic characteristics and beverage consumption were collected. Focus group discussions, guided by the Theory of Planned Behavior, explored adolescent views of a 20% tax on SSBs and the tax’s effect on adolescents’ consumption of these beverages. Focus groups were recorded and recordings transcribed verbatim. Data were coded and analyzed using NVivo software.

Results

Students understood the short- and long-term advantages and disadvantages of drinking SSBs. They understood that the opinions of those around them about SSBs might be affected by personal consumption. Students also understood the personal and economic effects of a 20% tax on SSBs, although the economics of a tax confused some. Students indicated that habit and environment could make reducing consumption of SSBs difficult, but they also gave suggestions, using habit and environment, to reduce consumption. Most students reported that they would decrease their consumption of SSBs if a 20% tax were implemented.

Conclusion

Taxes on SSBs could be used, with other strategies, to reduce adolescents’ high level of SSB consumption.

Studying the consumption and health outcomes of fiscal interventions (taxes and subsidies) on food and beverages in countries of different income classifications; a systematic review

Background

Governments use fiscal interventions (FIs) on food and beverages to encourage healthy food behaviour and positive health outcomes. The objective of this review was to study the behavioural and health outcomes of implemented food and beverage FIs in the form of taxes and subsidies in countries of different income classifications.

Methods

The present systematic review was conducted in accordance with Cochrane protocols. The search was carried out on academic and grey literature in English, for studies conducted in different countries on implemented FIs on food and non-alcoholic beverages and health outcomes, with a special focus on the income of those countries.

Results

Eighteen studies met the inclusion criteria and 14 were from peer- reviewed journals. Thirteen studies came from high-income (HI) countries, four from upper middle-income (UMI) countries and only one came from a lower middle-income (LMI) country. There were no studies from lower-income (LI) countries. Of these 18 studies; nine focused on taxes, all of which were from HI countries. Evidence suggests that FIs on foods can influence consumption of taxed and subsidized foods and consequently have the potential to improve health.

Conclusion

Although this review supports previous findings that FIs can have an impact on healthy food consumption, it also highlights the lack of evidence available from UMI, LMI and LI countries on such interventions. Therefore, evidence from HI countries may not be directly applicable to middle-income and LI countries. Similar research conducted in middle and low income countries will be beneficial in advocating policy makers on the effectiveness of FIs in countering the growing issues of non-communicable diseases in these countries.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2201-8) contains supplementary material, which is available to authorized users.

Targeted Beverage Taxes Influence Food and Beverage Purchases among Households with Preschool Children

BACKGROUND

How beverage taxes might influence purchases of foods and beverages among households with preschool children is unclear. Thus, we examined the relation between beverage taxes and food and beverage purchases among US households with a child 2-5 y of age.

OBJECTIVES

We examined how a potential tax on sugar-sweetened beverages (SSBs), or SSBs and >1% fat and/or high-sugar milk, would influence household food and beverage purchases among US households with a preschool child. We aimed to identify the lowest tax rate associated with meaningful changes in purchases.

METHODS

We used household food and beverage purchase data from households with a single child who participated in the 2009-2012 Nielsen Homescan Panel. A 2-part, multilevel panel model was used to examine the relation between beverage prices and food and beverage purchases. Logistic regression was used in the first part of the model to estimate the probability of a food/beverage being purchased, whereas the second part of the model used log-linear regression to estimate predicted changes in purchases among reporting households. Estimates from both parts were combined, and bootstrapping was performed to obtain corrected SEs. In separate models, prices of SSBs, or SSBs and >1% and/or high-sugar milk, were perturbed by +10%, +15%, and +20%. Predicted changes in food and beverage purchases were compared across models.

RESULTS

Price increases of 10%, 15%, and 20% on SSBs were associated with fewer purchases of juice drinks, whereas price increases of 10%, 15%, and 20% simulated on both SSBs plus >1% fat and/or high-sugar milk (combined tax) were associated with fewer kilocalories purchased from >1% fat, low-sugar milk, and meat, poultry, fish, and mixed meat dishes.

CONCLUSIONS

Our study provides further evidence that a tax on beverages high in sugar and/or fat may be associated with favorable changes in beverage purchases among US households with a preschool child.

Cost Effectiveness of a Sugar-Sweetened Beverage Excise Tax in the U.S

INTRODUCTION

Reducing sugar-sweetened beverage consumption through taxation is a promising public health response to the obesity epidemic in the U.S. This study quantifies the expected health and economic benefits of a national sugar-sweetened beverage excise tax of $0.01/ounce over 10 years.

METHODS

A cohort model was used to simulate the impact of the tax on BMI. Assuming ongoing implementation and effect maintenance, quality-adjusted life-years gained and disability-adjusted life-years and healthcare costs averted were estimated over the 2015-2025 period for the 2015 U.S.

POPULATION

Costs and health gains were discounted at 3% annually. Data were analyzed in 2014.

RESULTS

Implementing the tax nationally would cost $51 million in the first year. The tax would reduce sugar-sweetened beverage consumption by 20% and mean BMI by 0.16 (95% uncertainty interval [UI]=0.06, 0.37) units among youth and 0.08 (95% UI=0.03, 0.20) units among adults in the second year for a cost of $3.16 (95% UI=$1.24, $8.14) per BMI unit reduced. From 2015 to 2025, the policy would avert 101,000 disability-adjusted life-years (95% UI=34,800, 249,000); gain 871,000 quality-adjusted life-years (95% UI=342,000, 2,030,000); and result in $23.6 billion (95% UI=$9.33 billion, $54.9 billion) in healthcare cost savings. The tax would generate $12.5 billion in annual revenue (95% UI=$8.92, billion, $14.1 billion).

CONCLUSIONS

The proposed tax could substantially reduce BMI and healthcare expenditures and increase healthy life expectancy. Concerns regarding the potentially regressive tax may be addressed by reduced obesity disparities and progressive earmarking of tax revenue for health promotion.

Global Overview of the Epidemiology of Atherosclerotic Cardiovascular Disease

Atherosclerotic cardiovascular disease (ACD) is the leading cause of mortality worldwide. The objective of this paper is to provide an overview of the global burden of ACD and its risk factors and to discuss the main challenges and opportunities for prevention. Publicly available data from the Global Burden of Disease Study were analyzed for ischemic heart disease (IHD), ischemic stroke and ACD risk factors. Data from the WHO Global Health Observatory were used to describe prevalence of diverse cardiometabolic risk factors. World Bank Gross Domestic Product per capita (GDPc) information was used to categorize countries according to income level. Cardiovascular mortality decreased globally from 1990-2010 with important differences by GDPc; during 1990 there was a positive association between IHD mortality and GDPc. Higher-income countries had higher rates compared to those of lower-income countries. High levels of body mass index (BMI), blood pressure, glucose and cholesterol have a differential contribution to mortality by income group over time; high-income countries have been able to reduce the contribution from these risk factors in the last 20 years, whereas lower/middle income countries show an increasing trend in mortality attributable to high BMI and glucose. Although age-adjusted ACD mortality rate trends decreased globally, the absolute number of ACD deaths is increasing in part due to the growth of the population and aging, as well as to important lifestyle and food-system changes that likely attenuate gains in prevention. Population and individual level preventable causes of ACD must be aggressively and efficiently targeted in countries of lower economic development in order to reduce the growing burden of disease due to ACD.

Use and cumulation of evidence from modelling studies to inform policy on food taxes and subsidies: biting off more than we can chew?

Background

Food tax-subsidy policies are proposed to hold promise for helping to produce healthier patterns of food purchasing and consumption at population level. Evidence for their effects derives largely from simulation studies that explore the potential effects of untried policies using a mathematical modelling framework. This paper provides a critique first of the nature of the evidence derived from such simulation studies, and second of the challenges of cumulating that evidence to inform public health policy.

Discussion

Effects estimated by simulation studies of food taxes and subsidies can be expected to diverge in potentially important ways from those that would accrue in practice because these models are simplified, typically static, representations of complex adaptive systems. The level of confidence that can be placed in modelled estimates of effects is correspondingly low, and the level of associated uncertainty is high. Moreover, evidence from food tax-subsidy simulation studies cannot meaningfully be cumulated using currently available quantitative evidence synthesis methods, to reduce uncertainty about effects.

Summary

Simulation studies are critical for the initial phases of an incremental research process, for drawing together diverse evidence and exploring potential longer-term effects. While simulation studies of food taxes and subsidies provide a valuable and necessary input to the formulation of public health policy in this area, they are unlikely to be sufficient, and policy makers should not place excessive reliance on evidence from such studies, either singly or cumulatively. To reflect known and unknown limitations of the models, results of such studies should be interpreted cautiously as tentative projections. Modelling studies should increasingly be integrated with more empirical studies of the effects of food tax and subsidy policies in practice.

Healthy food subsidies and unhealthy food taxation: A systematic review of the evidence

The Global Burden of Disease Study and related studies report unhealthy diet is the leading risk for death and disability globally. Given the evidence associating diet and non-communicable diseases (NCDs), international and national health bodies including the World Health Organization and United Nations have called for population health interventions to improve diet as a means to target NCDs. One of the proposed interventions is to ensure healthy foods/beverages are more accessible to purchasers and unhealthy ones less accessible via fiscal policy, namely taxation and subsidies. The objective of this systematic review was to evaluate the evidence base to assess the effect of healthy food/beverage subsidies and unhealthy food/beverage taxation. A comprehensive review was conducted by searching PubMed, Medline, and Google Scholar for peer-reviewed publications and seventy-eight studies were identified for inclusion in this review. This review was performed in keeping with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. Although moderate in quality, there was consistent evidence that taxation and subsidy intervention influenced dietary behaviors. The quality, level and strength of evidence along with identified gaps in research support the need for further policies and ongoing evaluation of population-wide food/beverage subsidies and taxation. To maximize success and effect, this review suggests that food taxes and subsidies should be a minimum of 10 to 15% and preferably used in tandem. Implementation of population-wide polices for taxation and subsides with ongoing evaluation of intended and unintended effects are supported by this review.

Evaluating the Health Impacts of Food and Beverage Taxes

Several jurisdictions are now imposing taxes on food and beverages to prevent obesity (and related conditions). Existing evidence concerning their effects comes largely from simulation studies and trials in closed settings, both of which have limitations. Rigorous evaluation of actual taxes may provide richer evidence with greater external validity to support policy making. This article describes existing evaluation studies and outlines an implicit underlying theoretical framework for how taxes are expected to affect health. It then explores three important issues for future studies: selection of an appropriate evaluative perspective (comparing realist and biomedical experimental paradigms); approaches to causal inference; and the challenge of a low signal-to-noise ratio. We argue that evaluation should be informed by a realist perspective as well as making appropriate use of established empirical quasi-experimental approaches to testing causal effects. This should be underpinned by a theoretical framework that acknowledges complexity and the potential diversity of impacts.

Food prices and obesity: a review

In response to rising rates of obesity in the United States due in part to excess food consumption, researchers and policy makers have argued that levying food taxes on obesity-promoting foods, perhaps combined with subsidies on healthier options, would be an effective tool to stem the obesity epidemic. The extent to which overall energy intake or weight outcomes will improve as a result of these policies is ultimately an empirical question. This review examines the link between food or beverage price changes and energy intake or weight outcomes among U.S. consumers. Current evidence indicates that, by themselves, targeted food taxes and subsidies as considered to date are unlikely to have a major effect on individual weight or obesity prevalence. While research suggests that the effects are modest, food taxes and subsidies may play an important role in a multifaceted approach to reducing obesity incidence.

Food prices and body fatness among youths

We examine the effect of food prices on clinical measures of obesity, including body mass index (BMI) and percentage body fat (PBF) measures derived from bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DXA), among youths ages 12 through 18 in the National Health and Nutrition Examination Survey. This is the first study to consider clinically measured levels of body composition rather than BMI to investigate the effects of food prices on obesity outcomes among youths classified by gender and race/ethnicity. Our findings suggest that increases in the real price per calorie of food for home consumption and the real price of fast-food restaurant food lead to improvements in obesity outcomes among youths. We also find that a rise in the real price of fruits and vegetables leads to increased obesity. Finally, our results indicate that measures of PBF derived from BIA and DXA are no less sensitive and in some cases more sensitive to the prices just mentioned than BMI, and serve an important role in demonstrating that rising food prices (except fruit and vegetable prices) are indeed associated with reductions in obesity rather than with reductions in body size proportions alone.

Evidence that a tax on sugar sweetened beverages reduces the obesity rate: a meta-analysis

BACKGROUND

Excess intake of sugar sweetened beverages (SSBs) has been shown to result in weight gain. To address the growing epidemic of obesity, one option is to combine programmes that target individual behaviour change with a fiscal policy such as excise tax on SSBs. This study evaluates the literature on SSB taxes or price increases, and their potential impact on consumption levels, obesity, overweight and body mass index (BMI). The possibility of switching to alternative drinks is also considered.

METHODS

The following databases were used: Pubmed/Medline, The Cochrane Database of Systematic Reviews, Google Scholar, Econlit, National Bureau of Economics Research (NBER), Research Papers in Economics (RePEc). Articles published between January 2000 and January 2013, which reported changes in diet or BMI, overweight and/or obesity due to a tax on, or price change of, SSBs were included.

RESULTS

Nine articles met the criteria for the meta-analysis. Six were from the USA and one each from Mexico, Brazil and France. All showed negative own-price elasticity, which means that higher prices are associated with a lower demand for SSBs. Pooled own price-elasticity was -1.299 (95% CI: -1.089 - -1.509). Four articles reported cross-price elasticities, three from the USA and one from Mexico; higher prices for SSBs were associated with an increased demand for alternative beverages such as fruit juice (0.388, 95% CI: 0.009 - 0.767) and milk (0.129, 95% CI: -0.085 - 0.342), and a reduced demand for diet drinks (-0.423, 95% CI: -0.628 - -1.219). Six articles from the USA showed that a higher price could also lead to a decrease in BMI, and decrease the prevalence of overweight and obesity.

CONCLUSIONS

Taxing SSBs may reduce obesity. Future research should estimate price elasticities in low- and middle-income countries and identify potential health gains and the wider impact on jobs, monetary savings to the health sector, implementation costs and government revenue. Context-specific cost-effectiveness studies would allow policy makers to weigh these factors.

Taxing sugar-sweetened beverages: not a "holy grail" but a cup at least half comment on "food taxes: a new holy grail?"

In this commentary, we argue for the implementation of a sugar-sweetened beverage (SSB) tax as a tool to help address the global obesity and diabetes epidemics. Consumption of SSBs has increased exponentially over the last several decades, a trend that has been an important contributor to the obesity and diabetes epidemics. Prior evidence demonstrates that a SSB tax will likely decrease SSB consumption without significantly increasing consumption of other unhealthy food or beverages. Further, this tax is unlikely to have effects on income inequality and should not contribute to weight-based discrimination. A SSB tax also should raise revenue for government entities that already pay, through health care expenditures and health programs, for the consequences of excess SSB consumption.

Reducing Alaska Native paediatric oral health disparities: a systematic review of oral health interventions and a case study on multilevel strategies to reduce sugar-sweetened beverage intake

BACKGROUND

Tooth decay is the most common paediatric disease and there is a serious paediatric tooth decay epidemic in Alaska Native communities. When untreated, tooth decay can lead to pain, infection, systemic health problems, hospitalisations and in rare cases death, as well as school absenteeism, poor grades and low quality-of-life. The extent to which population-based oral health interventions have been conducted in Alaska Native paediatric populations is unknown.

OBJECTIVE

To conduct a systematic review of oral health interventions aimed at Alaska Native children below age 18 and to present a case study and conceptual model on multilevel intervention strategies aimed at reducing sugar-sweetened beverage (SSB) intake among Alaska Native children.

DESIGN

Based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement, the terms "Alaska Native", "children" and "oral health" were used to search Medline, Embase, Web of Science, GoogleScholar and health foundation websites (1970-2012) for relevant clinical trials and evaluation studies.

RESULTS

Eighty-five studies were found in Medline, Embase and Web of Science databases and there were 663 hits in GoogleScholar. A total of 9 publications were included in the qualitative review. These publications describe 3 interventions that focused on: reducing paediatric tooth decay by educating families and communities; providing dental chemotherapeutics to pregnant women; and training mid-level dental care providers. While these approaches have the potential to improve the oral health of Alaska Native children, there are unique challenges regarding intervention acceptability, reach and sustainability. A case study and conceptual model are presented on multilevel strategies to reduce SSB intake among Alaska Native children.

CONCLUSIONS

Few oral health interventions have been tested within Alaska Native communities. Community-centred multilevel interventions are promising approaches to improve the oral and systemic health of Alaska Native children. Future investigators should evaluate the feasibility of implementing multilevel interventions and policies within Alaska Native communities as a way to reduce children's health disparities.