From summer days playing Red Light, Green Light to driver’s education classes, we’ve all learned our traffic light basics. Green means go, slow down on yellow and stop on red.
Researchers at Massachusetts General Hospital (MGH) have applied this well-known concept to their own hospital cafeteria, and found labeling foods according to their nutritional value had an immediate and lasting impact on buying habits.
The study began in March 2010 when the research team started labeling cafeteria selections. Green for the healthiest items, such as fruits, vegetables and lean sources of protein; yellow for less healthy items, and red for those with little or no nutritional value. Several weeks before the labels were introduced, cafeteria cash registers began to identify and record each purchased item as red, yellow, or green.
At the end of the original six-month study, the team reported sales of all red items dropped 9.2% (and red beverages decreased a whopping 16.5%) and green item sales were up 4.5% (9.6% increase in beverages).
In phase two of the study, green items were moved to eye level and yellow and red options were relegated to lower shelves. This choice architecture change led to an additional 4.9% drop in red item sales, although green item sales dropped slightly (0.8%) as well.
“We believe this intervention was so successful because it was simple and easy to understand quickly. The labeling did not require any special skills and could be easily interpreted when a customer was in a rush,” says Anne Thorndike, MD, MPH, of the MGH division of General Medicine, who led the study.
The results were promising, but would they last?
Looking back over two years of accumulated data, the same MGH research team says yes — the impact of these interventions had a lasting impact. At the end of the second year of the program, purchases of green items were up 12% and red purchases dropped 20%. Red beverage purchases were down nearly 40% while green beverage purchases increased 10%. The changes were similar for all types of employees and cafeteria sales during the study period were stable.
“These findings are the most important of our research thus far because they show a food labeling and product placement intervention can promote healthy choices that persist over the long term, with no evidence of ‘label fatigue,’ ” says Thorndike. “The next steps will be to develop even more effective ways to promote healthy choices through the food service environment and translate these strategies to other worksite, institutional, or retail settings.”