Want to Change Food Habits? Study Says Use ‘Traffic Lights’

Source: http://www.flickr.com/photos/lac-bac/

Source: http://www.flickr.com/photos/lac-bac/

We use them to ease congestion and create traffic patterns, but could the color scheme on stoplights also be a way to combat obesity? A study published in the February issue of the American Journal of Preventive Medicine explains why “traffic light” labeling on food products could reduce the number of unhealthy choices made by consumers on a daily basis. When this system was implemented, a 20 percent reduction in red (unhealthy) choices occurred over a two-year period, and “green light” sales increased by 12 percent.

“Our current results show that the significant changes in the purchase patterns of both hospital employees and all customers resulting from the labels and the choice architecture program did not fade away as cafeteria patrons became used to them,” Anne Thorndike, MD, MPH, of the MGH Division of General Medicine, said in a Massachusetts General Hospital press release. “This is good evidence that these changes in healthy choices persist over time.” Thorndike led the study.

Sales from the main cafeteria at Massachusetts General Hospital between February 2009 and December 2012 were under studied. A three-month baseline was used to gather sales data before the new system was implemented. The first change was the traffic light labels, which after three months were followed by “choice architecture” changes. The latter did things like move green-lighted items to more prominent positions or place an option like salad next to pizza. The alterations are permanent, and signs were prominently posted to describe the meanings of the labels. The study wanted to determine how the label intervention impacted behavior in the long run. 

Ratings for the items were based on positive and negative factors. If the main ingredient was a fruit or vegetable, whole grain, lean protein, or low fat, it received positive marks. The negative criteria were based on the item’s caloric value and saturated fat content. When the positive marks outnumbered negative, the item was labeled with a green light. If a pro-con equilibrium was reached, the rating was yellow. When there were more negative aspects for the product, the light label was red. The only exceptions were bottled water and diet sodas; no positive factor is associated with diet soda, but it and bottled water have zero calories and were given a green light.

Red items comprised 24 percent of all cafeteria purchases in the baseline data. By the 12-month follow up, this had fallen to 21 percent, and it remained at that level in the 24-month evaluation. Green transactions were 46 percent of all sales after 24 months, an increase over the 41 percent baseline figure. The largest decrease was among red beverages: Two years after the new labels began, there was a 39 percent dropoff in sales for these drinks. Beverages with a green light saw a 10 percent increase and sales of the yellow beverages were up 16 percent.

“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,’” Thorndike said. “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.”

Long-term outcomes were measurable because employees at the hospital pay for meals with a “platinum plate” card. The cards are employee-specific and linked to demographic information about the individual. To understand effects over time, cohorts were formed based on how often an employee used his or her card at the main cafeteria. Data evaluations took place every three months. To be included, employees needed to make at least three purchases during the period.

The study broke down beverage sales along race and occupation. At the end of the observation period, sales of red beverages had decreased while green sales increased across the board. Employees in “management/clinician” positions were most likely to stop buying “red” drinks (44 percent decrease), and technicians had the biggest increase (21 percent) for buying a drink with a green label.

The authors of the study believe its findings are important for future initiatives. In the discussion portion, the team notes that “simple food environment interventions can play a major role in public health policies to reduce obesity.” Adding labels and making other minor changes can be introduced without negatively impacting bottom line, as well. Throughout the study, sales in the cafeteria did not decline.

As a result, the food industry should embrace ideas like traffic light labeling to help customers make informed choices. Nutrition labels themselves can be confusing, but a simple color code is a universal language. The researchers conclude by saying more collaboration needs to take place between health officials and those in the industry to make cumulative changes that can have a beneficial impact on the general population’s wellness.

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