(CN) — Warning labels with graphic images linking sugary drink consumption with tooth decay, Type 2 diabetes and obesity appear to reduce purchases of the drinks more effectively than calorie counts or text warnings, a new study finds.
The Monday report in the journal Psychological Science compares the effectiveness of three types of labels: lists of the caloric values of the drinks, text warning and graphic warnings about the health risks.
“Warning labels have been around a long time for tobacco products, but they’re a new concept for sugary drinks,” said co-lead author Grant Donnelly, assistant professor of marketing at Ohio State University. “Text warning labels have been passed in San Francisco and are being considered in many jurisdictions in the U.S. and around the world.
“Ours is the first study to evaluate the effectiveness of sugary drink warning labels in the field.”
Each type of label, displayed near bottled and fountain beverages in a hospital cafeteria in Massachusetts, was tested consecutively, with two-week “washout” periods between tests, during which no label was exhibited. More than 20,000 beverages were purchased during the study.
During the weeks when the graphic warnings were displayed, the share of sugar-sweetened drinks sold in the cafeteria fell by 14.8 percent. Consumers appeared to substitute bottled water for the sugary drinks. The average calories per drink sold also shrank, from 88 to 75.
The calorie labels and text warnings had minimal effect on beverage sales.
The team tested its findings by conducting two follow-up studies online.
In the first, consumers were asked about how seeing a graphic warning label would affect their drink purchases. The results showed that the graphic warnings increased negative reactions toward sugary drinks and fostered greater consideration of health risks over taste.
The second was a national online study in which more than 400 participants were asked whether they support adding these labels to sugary drinks. Once informed that graphic warnings were effective at curtailing sugar-sweetened beverage consumption, they were just as supportive of the graphic warning labels as they were the calorie labels and text warnings.
“Sugar-sweetened beverages are the largest source of added sugars in the American diet and reducing intake of these beverages could improve population health,” said co-lead author Laura Zatz, a doctoral student at Harvard University.
“As policymakers search for ways to reduce excess consumption of sugary drinks, graphic warning labels merit consideration as a tool that can empower consumers with salient information to encourage healthier choices.”