The study shows sales were cut by almost 10% and the number of people buying water may have increased also, with bottled water sales in Berkeley increasing by 15.6% after the introduction of the tax.
"Soda and other sugary drinks are the number one source of added sugar in the American diet, and are linked to increased risk of diabetes and other diseases, like heart and liver disease, obesity, and tooth decay", shows the Berkeley Soda Tax FAQ.
"The Berkeley tax is a home run - it helped residents make healthier choices, it raised revenue for promoting health, and we saw no evidence of higher grocery bills for consumers or harm to local business revenue", Silver said in a statement. "But if soda taxes didn't make a significant dent in soda consumption, the industry wouldn't be fighting taxes so hard".
Consumers' average grocery bill did not increase because of the tax.
The tax costs were passed through to consumers on taxed products in many, but not all, stores, the study said. Purchases of water went up by 15.6 percent and other untaxed drinks increased by 4.4 percent. Sugar-sweetened drink sales fell 9.6 percent compared to predicted sales without the tax, while sales of untaxed beverages, like water and milk, rose 3.5 percent. However, stores in Berkeley fared better than stores in surrounding areas.
The report was welcomed by officials in Philly where a 1.5-cents-per-ounce tax was enacted.
The new study, reported in PLoS Medicine, evaluated changes in beverage sales in Berkeley during the tax's first year. The revenue will be used to support schools, a universal pre-Kindergarten program, recreation centers, and health initiatives. Her study did not attempt to judge the tax's impact on obesity and diabetes rates.
"I am very encouraged by the study and I am optimistic that we will see a similar impact here, Farley said. In Philadelphia, we face a severe health crisis with our twin epidemics of obesity and diabetes, and sugary drinks are the biggest single contributor". They conducted three before-and-after studies: one of store scanner records from 15.5 million checkouts in two chains of large groceries in Berkeley and comparison cities; one of 26 stores of various types in Berkeley; and one random digit dialing telephone survey of 957 adult Berkeley residents.
Self-reported consumption of sugary drinks fell, but not significantly so, among Berkeley residents as measured in grams (-19.8%; P=0.49) and in mean caloric intake (-13.3%; P=0.56).
"This suggests we will see a much larger tax impact in other USA cities with similar or higher tax levels", said Dr. Shu Wen Ng.
Researchers believe soda taxes in those communities could have a greater impact than in Berkeley because per capita consumption of sweetened beverages is about three times lower in Berkeley than the country as a whole, Silver said. The city mayor appears determined to succeed in their battle against the beverage giant, as they plan to continue with their tax plan even after the Pepsi threat of job cuts in the city.