Philadelphia beverage tax: Did it curb childhood obesity?

Despite slashing sugary drink sales by over 25%, Philadelphia’s beverage tax reveals nuanced effects on children’s weight, spotlighting the complexity of tackling pediatric obesity.

Study: The Philadelphia Beverage Tax and Pediatric Weight Outcomes. Image Credit: Shutterstock AI / Shutterstock.com 

A recent JAMA Pediatrics study investigates the impact of the 2017 Philadelphia beverage tax on pediatric weight outcomes.

How does added sugar affect pediatric health?

Approximately 65% of children in the United States exceed recommended sugar intake levels due to higher consumption of sugar-sweetened beverages (SSBs). A higher intake of excess sugar increases the risk of metabolic syndrome, weight gain, and dental caries in children.

In the U.S., SSB taxation has been implemented in seven cities and the Navajo Nation in an effort to prevent the adverse health effects associated with SSB consumption. On January 1, 2017, Philadelphia initiated a beverage tax of 1.5 cents for every ounce, equating to about 50 cents/liter, on artificially sweetened beverages and SSBs. Notably, the Philadelphia beverage tax is not applied to powdered forms of beverages, sweetened alcoholic beverages, or 100% natural juices.

Philadelphia beverage tax decreased SSB sales by 25-35%, with one study reporting that soda intake was reduced by 0.81 servings each week among high school students. These findings indicate the possibility that beverage taxes may also influence pediatric weight outcomes.

About the study

Difference-in-differences analyses were performed to estimate how beverage tax impacted the weight of children in Philadelphia as compared to children in Pennsylvania and New Jersey counties where this tax was not imposed. All relevant data were collected from electronic health records (EHRs) from the pediatric health system in the Philadelphia region.

Children between two and eighteen years of age with at least one pre- and post-tax visit to clinics were included in the current study. Weight and height measurements were recorded between January 1, 2014, and December 31, 2019.

Any children who resided outside the pre-determined study sites were excluded, as were children with pre-existing medical issues that could affect their normal growth.

Standardized BMI (zBMI) and obesity prevalence were measured based on standardized guidelines from the U.S. Centers for Disease Control and Prevention (CDC).

Study findings

Initially, 136,078 children were included in the study cohort, and 258,584 children in the cross-sectional sample. However, approximately 3% of children were excluded due to missing covariates.

The final study cohort included children of White, Black, Hispanic, and other ethnicities. Approximately 16% of the Philadelphia cohort had a 95^th percentile or higher BMI. Notably, 79% of Philadelphia youth lived in lower socioeconomic status.

The pre-tax control group, which primarily comprised White children residing in low Yost Index census tracts, exhibited lower zBMI than the Philadelphia cohort. The cross-sectional sample indicated similar differences between Philadelphia and the control group.

No significant difference in zBMI was observed between panel and cross-sectional analyses after two years of the Philadelphia beverage tax implementation. Furthermore, no significant difference in obesity prevalence was observed between groups.

Subgroup analyses revealed that the Philadelphia beverage tax affected zBMI for White youth in both panel and cohort samples. Thus, White Philadelphia youth experienced a greater zBMI reduction than controls between the pre-and post-tax periods. However, this change was not observed for Black youths.

The cross-sectional analysis revealed no significant difference in zBMI for children between two and five years of age. However, zBMI increased for children between six and twelve years of age, whereas it was reduced for those between thirteen and eighteen. No change in zBMI was observed by sex.

Although no significant change in overall pediatric weight was observed after two years of the beverage tax in Philadelphia, a substantial reduction in SSB and artificially sweetened beverage purchases was observed. Importantly, the reduced consumption of added sugars can improve health, even without causing changes in body weight.

Conclusions

The Philadelphia beverage tax did not significantly impact pediatric weight overall. However, some small and inconsistent changes of limited clinical significance were observed in sub-groups after two years of implementation.

Previous studies have indicated that implementing a beverage tax improved diet quality. However, the current study revealed that the tax did not significantly impact pediatric weight.