Study details and key findings

For the study, researchers analyzed changes in prices and purchases of sugar-sweetened beverages (SSBs) after soda taxes were implemented in five cities:

1.       Boulder, CO

2.       Philadelphia, PA

3.       Oakland, CA

4.       Seattle, WA

5.       San Francisco, CA

Data was taken from Jan. 1, 2012, to Feb. 29, 2020, and the analysis occurred between June 1, 2022, and Sept. 29, 2023. Changes in prices and purchases, which was measured as volume in ounces, in the five cities in the two years following tax implementation were compared with other cities without soda taxes as control groups.

Overall, the researchers found that SSB prices increased by an average of 33.1% in the two years after a soda tax was implemented. This corresponded to an average price increase of 1.3 cents per ounce. At the same time, SSB purchases, by total volume, decreased by an average of 33%.

"In other words, for every 1% increase in price, we find that purchases fall by about 1%," said Scott Kaplan, an economics professor at the U.S. Naval Academy and the study's lead author. These findings were observed immediately after tax implementation and sustained in the months after.

Although previous studies have found that sales of SSBs increase in surrounding areas after soda taxes are implemented, indicating traveling for cheaper SSBs, the current study did not find any evidence of increased cross-border purchases.

Commentary

According to CDC data, more than 60% of Americans drink an SSB every day, with the average person consuming 145 calories a day from such drinks. High consumption of these drinks can have negative health effects. Research has linked SSBs to weight gain, high cholesterol, high blood pressure, Type 2 diabetes, heart disease, and more.

Dean Schillinger, director of the Health Communications Research Program at the University of California, San Francisco, who led the current study, said that reducing sugar consumption would greatly benefit American healthcare.

"When you think about the fact that one in four dollars of our health care spending goes to diabetes alone, any kind of incremental improvement we can get will have massive effects," Schillinger said.

To increase the potential public health benefits of soda taxes, Schillinger and Kaplan say that they should be implemented at a broader level beyond cities so that people are not simply crossing borders to buy cheaper SSBs.

"Taxation is a very important part of a multi-faceted solution" to get people to drink fewer SSBs, Schillinger said. He also noted that tax increases combined with marketing campaigns and regulations have helped change public behavior around tobacco use.

Health organizations have also supported soda taxes as a way to curb consumption of sugary drinks. In 2019, the American Heart Association and the American Academy of Pediatricians both endorsed soda taxes as a way to reduce the risks of childhood obesity. Similarly, the World Health Organization last month encouraged countries to increase taxes on sugary drinks to help promote healthier diets.

In response to the current study, the American Beverage Association (ABA) pushed back on the idea of soda taxes and said the beverage industry was already helping consumers reduce their sugar intake by offering more choices with less sugar.

"[T]oday nearly 60% of all beverages sold have zero sugar and the calories that people get from beverages has decreased to its lowest level in decades," said ABA spokesperson William Dermody. "On the other hand, a beverage tax has never been shown to improve public health or to reduce beverage calories in a significant way."

"Beverage companies, government and public health can work together to support families in their effort to find balance without unproductive taxes that hurt consumers, small businesses and their employees," he added. (Godoy, "Shots," NPR, 1/6; Weintraub, USA Today, 1/5; Kaplan et al., JAMA Health Forum, 1/5)

Writing for the New York Times, Sophie Egan surveyed some of the top nutrition experts in the country to identify — and debunk — 10 common nutrition myths about fat, plant-based protein, dairy, and more.