'Traffic light' labelling works - on some consumers

A ‘traffic light’ food labelling system appears to be working at the Massachusetts General Hospital (MGH), with customers who noticed the labelling - and are influenced by nutrition information - opting for healthier options more often.

“Several small, experimental studies have suggested that ‘traffic light’ labels can be an effective method of promoting healthier choices, but there have been few real-world studies of customers’ perceptions and purchasing behaviours in response to this type of labelling,” said Lillian Sonnenberg, DSc, RD, LDN, MGH Nutrition and Food Service, author of a report on the study, which was published in the October issue of Preventive Medicine.

“Our results suggest that these labels are an effective method for conveying information about healthy and unhealthy choices and for prompting changes in purchasing behaviour.”

To find a simpler way to encourage more healthful purchases at the hospital’s food service locations, MGH Nutrition and Food Service put together a plan that started with colour-coding each item sold in the main cafeteria, plus signage encouraging more frequent purchases of green-labelled items and discouraging purchases of red-labelled items.

Cafeteria cash registers were programmed to record each purchased item as green, yellow or red, starting three months before the labelling intervention began.

The month before and two months after the labelling intervention began, participants were surveyed about their purchasing habits and the impact of nutrition labelling on their choices. After the labelling intervention, they were also asked whether they had noticed the labels and whether they had influenced their purchases.

While 46% of respondents indicated that health/nutrition was an important factor in their choices prior to the labelling intervention, 61% did so after the intervention. The percentage of those indicating that they looked at available nutritional information before a purchase doubled from 15 to 33%, although there was no significant difference in the percentage reporting they usually or always choose healthy foods. Respondents who reported noticing the new labels bought a greater proportion of green items and fewer red items than those who did not notice, and the influence was even stronger among those who indicated being influenced by the labels.

“While our results can’t give concrete information about customers’ nutritional knowledge, people were more likely to indicate that health and nutrition were important factors in their decision when the labels were in place, and those who noticed the labels were more likely to purchase healthy items,” Sonnenberg said.

“Although we haven’t directly compared these ‘traffic light’ labels to other systems, we can say that these labels appear to be more effective than the standard nutritional labelling available on packaged products. The strategy is simpler for customers to understand at the point of purchase and, once the appropriate labels for each item are determined, is relatively easy to implement.”