Association Between Local and State Sugar-Sweetened Beverage Taxes, Beverage Purchasing Patterns and Weight
Adult obesity and adolescent overweight rates have increased exponentially over the past three decades. Coincident with these rising rates, there has been a marked increase in the consumption of sugar-sweetened beverages (SSBs). SSB consumption has been associated with higher energy intake, reduced vitamin and nutrient intake, reductions in consumption of healthier beverages such as milk, and increased body mass index (BMI), risk of obesity and diabetes. This research will examine the relationship between state and local sales taxes on SSBs, household beverage purchasing patterns, and weight outcomes among adults and adolescents in the U.S. for the three-year period, 2010-2012. Specifically, we will examine the relationship between state and local sales taxes on sports drinks, juice drinks containing less than 50% fruit juice, sweetened iced teas, and regular (non-diet) soda and: (1) beverage purchasing patterns for SSBs and non-SSBs (volume purchased and expenditure on such products); and (2) weight outcomes including BMI and obesity.
This longitudinal study will build on the emerging soda tax-related literature to include examination of the relationship between state and local taxes on other SSBs (in addition to soda) as well as to add in the local tax component to previously conducted soda analyses. The specific aims of this study are to test the hypotheses: 1) that higher SSB state and local taxes will lead to lower household SSB purchasing; and (2) that higher SSB state and local taxes will lead to lower BMI/obesity rates.
Structural equation models (SEM) with ordinary least squares (OLS) regression and logit models (as appropriate) will link the tax data with: household purchasing and expenditure data obtained from the AC Nielsen Homescan data for 2010-12; adult BMI/weight outcomes obtained from the Behavioral Risk Factor Surveillance System for the years 2010-12; longitudinal adult (ages 26-32) BMI/weight outcomes obtained from the National Longitudinal Survey of Youth 1997 cohort (NLSY97) for the years 2010-12; and adolescent measured weight outcomes obtained from the Children of the National Longitudinal Survey of Youth 1979 (CNLSY79) cohort for the years 2010 and 2012. State tax data will be obtained from the Robert Wood Johnson Foundation-supported Bridging the Gap Program; the local tax data will be compiled through primary data collection.
All analyses will account for the moderating impact of individual level demographic and SES characteristics; will include state clustering; and will control for county level demographic and SES characteristics, health rankings and food store availability; state obesity and cigarette tax rates; year, and state fixed effects. We also will control for pre-tax prices; conduct sensitivity analyses to account for individual level physical activity rates (in the BMI models); and test for endogeneity using a series of instrumental variables. This research will provide additional evidence for policymakers as to whether implementing or increasing state and local SSB taxes is likely to affect SSB and non-SSB purchases and related weight outcomes.