Dietary signals: Traffic light food labelling encourages healthier choices among Japanese students – RCT

By Audrey Yow

- Last updated on GMT

Traffic light food labelling encouraged healthier food choices among Japanese college students, and now has the potential to be used nationwide. © Getty Images
Traffic light food labelling encouraged healthier food choices among Japanese college students, and now has the potential to be used nationwide. © Getty Images

Related tags Traffic light labelling Nutrition health & wellbeing

Traffic light food labelling encouraged healthier food choices among Japanese college students, and now has the potential to be used nationwide, say researchers.

Researchers in Japan assessed the influence of Traffic Light Food (TLF) labels on Japanese college students in a randomised controlled trial (RCT) and found that their use encouraged healthy dietary choices.

“Dietary choice scores indicated that the TLF-labelled group made significantly healthier dietary choices than the unlabelled group,”​ wrote the researchers in BMC Public Health​.

“The use of FOP (front-of-pack) nutrition labels should be considered in Japan to prevent lifestyle-related diseases through healthy dietary choices.”

Displaying FOP nutrition information labels, such as the TLF one, has been implemented worldwide to prevent lifestyle-related diseases. To investigate its potential in influencing healthy dietary choices, the researchers undertook an RCT on 69 Japanese college students between April 11 and May 2, 2022.

Data were collected through an online survey using a web-based questionnaire administered through Google Forms. Participants responded to questions on health- and nutrient-related awareness, stress, TLF labelling, and food choices.

To ensure a label system that reflected the cultural context of Japan, researchers created the TLF labels thus: red for most popular, yellow for moderately popular, and blue for the least popular meals. The colour blue was chosen instead of UK Food Standards Agency (FSA) green label because in Japan, the ‘go’ signal in traffic lights is perceived as blue.

The researchers also wanted to mirror the variety found in real-world food packaging meals and ensure the TLF labels adhered to internationally recognised nutritional standards. They wanted to assess dietary attentiveness to specific nutrients as well. Hence, they included measures such as not uniformly colour coding all nutritional components. For example, saturated fats and sugars were randomly assigned blue or yellow. Additionally, for meals labelled blue, the values corresponded to the ‘healthier’ range of the FSA’s criteria.

The participants were randomly divided into two groups to assess whether they would choose a healthy diet using TLF labels through an RCT. The intervention group would be shown food images with TLF labels, while the non-intervention group would be shown food images without TLF labels.

For three weeks, participants selected their dinner from 15 images of meals. In the first week, the images had no TLF labels. After this, a one-week break (washout period) was imposed. Then, in the third week, the intervention group selected their dinner from images with nutrition labels, while the non-intervention group made their selection after viewing the same images without labels.

At the end of the trial, the participants were assessed based on the following: Whether the group who saw the TLF labels had an increased percentage of people who consistently choose a healthy diet throughout the week (seven days from Monday to Sunday) than the group without the TLF label; Whether the presence or absence of the TLF labels made a difference in the percentage of people who are conscious of healthy dietary intake and nutritional components such as calories, carbohydrates, and fats when making dietary choices; Whether the use of TLF labels increased the stress caused by withholding what they wanted to eat.

In the intervention group, there was a 20.6% increase in blue label choices and a 12.6% decrease in red label choices by the end of the trial. Compared to the non-intervention group, it showed a 10.5% higher preference for blue labels and a 13.3% lower preference for red labels.

“This difference was statistically significant, indicating an increase in healthy food choices due to labelling,” ​said the researchers.

The intervention group also had 40% more people who were aware of the nutritional balance of their overall diet. And for each nutritional component, this group had a significantly higher proportion of people conscious of nutritional components other than dietary fibre. Furthermore, a significant increase was observed in proteins not listed on the label, as well as salt and total fat.

The researchers did not observe any sign of psychological stress caused by the presence and absence of the TLF labels.

And at the end of the study, more than 90% of all participants felt that TLF labels improved health awareness and were effective in encouraging healthier meal choices and would like manufacturers to place such labels on the front of food packaging.

“The use of TLF labelling increased the percentage of people who opt for a continuously healthy diet throughout one week and raised awareness of nutritional components. This approach shows promise for promoting healthier choices and preventing lifestyle-related diseases in Japan,”​ concluded the researchers.

“Future research should investigate its broader impact on diverse demographics. Policymakers are advised to consider these findings for public health strategies, potentially informing both national and global nutritional labelling practices.”

Source: BMC Public Health


“Investigation of the 1-week effect of traffic light nutrition labeling on diet selection among Japanese university students: a randomized controlled trial”

Authors: Nobuyuki Wakui, Raini Matsuoka et al​.

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