Study Suggests A Soda Tax Could Impact Consumption Behavior

01 Sep 2016 --- A study published in the American Journal of Public Health shows that a small tax on sugar-sweetened beverages may result in reduced consumption of those beverages.

Five months after Berkeley, Calif., implemented its penny-per-ounce tax on sugar-sweetened beverages, lower-income residents had reduced their consumption by 21%, compared to the pre-tax days. Meanwhile, their counterparts in neighboring Oakland and San Francisco increased the amount of sugary drinks consumed by 4% during the same period.

To see whether the tax would change anyone’s buying habits, the researchers from the University of California, Berkeley and the University of California, San Francisco sent interviewers to busy intersections in census tracts with large numbers of low-income and non-white residents. They asked residents in Berkeley, Oakland, and San Francisco how often they drank beverages in five categories: full-calorie soda, sports drinks, energy drinks, fruit drinks, and sweetened tea or coffee concoctions. The first set of interviews occurred at least eight months before the tax went into effect, and the second set was completed five months after it was implemented. Nearly 3,000 people answered the questions in either English or Spanish.

After controlling for the age, gender, race, ethnicity and education level of those who took the survey, researchers found that the drinking habits of Berkeley residents were starkly different from those of similar people in Oakland and San Francisco. Those in Berkeley drank 26% less regular soda after the tax, while their neighbors in San Francisco and Oakland drank 10% more. The gap was even more pronounced in the case of sports drinks - those in Berkeley cut back by 36%, while those in Oakland and San Francisco drank 21% more. In addition, Berkeley residents increased their water consumption by 63%, while in neighboring cities, low-income residents drank only 19% more water during the study period.

More than one in five Berkeley residents told the survey-takers that the tax had caused them to change their drinking habits. Among these 124 people, 82% said they consumed sugary drinks less frequently, and 40% said they had reduced their portion sizes.

“While Berkeley is just one small city, this is an important first step in identifying tools that can move the needle on population health,” explained Kristine Madsen, a public health researcher at UC Berkeley and senior author of the study.