The American Journal of Public Health recently published a study about the effects of sugar-sweetened beverage tax in Berkeley, Oakland, and San Francisco, California. The study targeted two neighborhoods in each of these three cities with the highest amount of African American and Hispanic residents according to the 2010 Census data (Lee et al.). The study mostly looked at the Berkeley neighborhoods and used the others for comparison. The results between the Berkeley group and the comparison group are significantly different. Based on this study, would a sugar-sweetened beverage tax overall reduce the consumption of sugar-sweetened beverages?
In a cross-sectional design, this study looked at sugar-sweetened beverage consumption rates in demographically diverse neighborhoods before the sugar-sweetened beverage tax and three years after. The study was done by having data collectors stand near “heavily foot-trafficked” intersections and adults filling out a fifteen question survey that asked how many times a day a person drank sugar-sweetened beverages, and the results were converted to frequencies. Results showed a decrease in consumed sugar-sweetened beverages by 52.5% in Berkeley, however the study states that “there were no significant consumption changes in the comparison group” (Lee et al.). So while the questionnaires being answered by adults in Berkeley were decreasing their sugar-sweetened beverage consumption and increasing their water intake significantly, other neighborhoods in different cities that experienced the same tax, did not see as a significant change in reducing consumption of sugar-sweetened beverages.
The study done used excellent data collecting techniques by using cross-sectional questions repeated from 2014 to 2017, so they had a lot of information and data to process. In the article it states that pretax consumption was compared to an average of post tax consumption, and checked for robustness in unweighted models and modified-inverse probability weighted models. They also used results in the Berkley study and compared it to Mexico’s tax on sugar-sweetened beverages. The results in Mexico’s tax showed the tax affected lower SES households than higher SES households. The Berkeley study used this example from Mexico to use as evidence in concluding lower income households could be more responsive to the tax. Lower income households have disproportionate rates of cardiometabolic disease which are affected by intake of sugar-sweetened beverages. That is not to say high income people do not have cardiometabolic diseases, but are generally more educated and have better access to healthy options, therefore reducing the rates of such diseases.
The study concludes persistent declines of consumed sugar-sweetened beverages as a result of the tax could significantly reduce obesity and affiliated diseases, especially in populations with high initial sugar-sweetened beverage consumption. The study targeted neighborhoods with high diversity populations, but never clearly connected those neighborhoods with lower SES status. Although the study inferred that the tax would affect lower income households and a more diverse population more, the study never explained that the two are connected. They Berkeley study discussed implications should be to implement the tax in other places because consumed sugar-sweetened beverages lowered by half of beverages consumed daily of=ver three years. However, these results were only seen in the Berkeley neighborhoods, and not in the compared neighborhoods.The broader implications suggest that the tax would lower obesity and cardiometabolic disease rates in other areas, especially low SES areas, and that the tax an effective policy option to increase public health.
This conclusion, no matter how robust the study is, continues to be problematic. The study demonstrates success in Berkeley, but failure in other cities. No changes in the comparison group with the same demographic surveyed and the same tax should not suggest a success, or continuing policy change. The study suggests that a sugar-sweetened beverage tax is an effective way to improve public health, relating to obesity. Consumption of sugar beverages may decrease in lower income households, but that would not increase the public health of higher income households who might not be affected by the tax because they can afford to drink sugar-sweetened beverages with physical income, and better healthcare. Discussions also only accounted for adults, and according to the CDC, obesity by sugar-sweetened beverage consumption affects young adolescents more than adults. The Berkeley study does not demonstrate effective results in the change of sugar-sweetened beverages relating to the decrease of sugar-sweetened beverages consumed in larger areas.
References:
“Sugar Sweetened Beverage Intake”. Centers For Disease Control And Prevention, 2019, https://www.cdc.gov/nutrition/data-statistics/sugar-sweetened-beverages-intake.html.
Lee, Matthew M. et al. “Sugar-Sweetened Beverage Consumption 3 Years After The Berkeley, California, Sugar-Sweetened Beverage Tax”. American Journal Of Public Health, 2019, pp. e1-e3. American Public Health Association, doi:10.2105/ajph.2019.304971. Accessed 24 Feb 2019.
Data/Society/Decision-making Spring 2019 