Bumping up the price of soda pushed people away from the sugar-sweetened soft drinks that are blamed for fueling the obesity epidemic, according to results of an experiment conducted in a Boston hospital cafeteria. Charging significantly more also proved more powerful than an educational campaign on the health benefits of cutting back on soda.
Dr. Jason Block of Brigham and Women's Hospital led the study that was carried out in his hospital cafeteria. In the first phase, the price of a 20-ounce bottle of sweetened soda was jacked up from $1.30 to $1.75. The price of diet soda remained the same. Sales of the sweetened beverage went down by 26 percent, as some customers appeared to switch to diet sodas, whose sales shot up 20 percent. Fruit drinks, which are also high in calories because they, too, are sweetened by sugar, did not become more popular. Their price did not change.
In the second phase of the experiment, the price increase was rolled back for a "washout period" before an educational campaign was launched, with signs pitching weight loss as a benefit of spurning soda. But soda consumption didn't budge until the price increase was reintroduced. Then sales dropped by 18 percent. At neighboring Beth Israel Deaconess Medical Center, whose cafeteria acted as a comparison, prices were left unchanged and beverage sales didn't change significantly, ruling out any external force.
"It could be people just aren't responding to the health message or it could be we need better health messages," Block said in an interview. The study appears today in the American Journal of Public Health.
Block also said the study needs to be repeated in different populations. A similar experiment will test price increases and educational campaigns across many college campuses.
The current study's findings are consistent with research showing that substantial taxes on cigarettes and alcohol do cut consumption, Block said. Many places, including Massachusetts, are also considering soda taxes as a policy initiative.
"We need to know what works," Block said.
The American Beverage Association disagreed with the paper.
“Singling out one item as the cause of obesity completely misses the mark,” Susan Neely,
president and CEO of the trade group, said in an e-mailed statement. “If we really want to solve this national public health challenge, we must focus on educating Americans through comprehensive approaches that include nutrition education based in fact and focusing on total diet and exercise –- not efforts that are simplistic and will be ineffective.”