Nudges improve food choices and cut calories when shopping for groceries online, Duke-NUS study shows

Singapore, 25 April 2025—A team of Duke-NUS Medical School researchers designed and tested a new digital toolkit that helps consumers make healthier grocery choices online—an innovation that could play a major role in the global fight against chronic diseases such as heart disease, stroke and diabetes.

In their study, published in the American Journal of Preventive Medicine, the researchers found that when simple but strategic digital features, such as colour-coded nutritional quality signals and a healthier alternative prompt, were added to an online grocery shopping platform, the nutritional quality of shoppers’ carts improved significantly.

The team’s findings verified the effectiveness of deploying front-of-package (FOP) labels—which only marginally improve diet quality when used alone—alongside other interventions.

In a randomised trial conducted on NUSMart, an online grocery store designed by the Duke-NUS team, study participants were randomly divided into two groups and asked to make a total of three orders over a period of three to six weeks. While those assigned to the control group used a standard version of the store, those assigned to the experimental group used a version of the store with additional digital features, including:

Signalling nutritional quality with a traffic light: FOP labels resembling traffic light signals alerted shoppers to food products’ nutritional quality using three colour bands—green (best), amber and red with an “X” mark—for easy identification of foods to avoid.

Items were sorted into the colour bands based on their Nutri-Score (NS)[1] points, which were assigned according to energy, sugar, sodium, saturated fat, fruit/vegetable, protein, and dietary fibre levels per 100g/ml. The points were then converted into grades on a five-letter grading system, with A being the healthiest and E being the least healthy.

Sorting groceries by nutritional value: Using food products’ NS points, the researchers presented the items by order of nutritional value, with the healthiest options appearing first. Items in the control version of NUSMart appeared in alphabetical order.

Showing real-time cart feedback: Participants could track the nutritional quality of their grocery carts via a pie chart that indicated the proportion of items in each colour band. They could also compare their carts with a reference cart for health grocery shopping, which the researchers had curated using past data.

Suggesting healthier options: Shoppers could also view up to four healthier alternatives with similar prices and characteristics to each selected food product and replace their chosen product with the healthier alternative at the click of a button.

With these interventions, the nutritional quality of participants’ grocery carts improved from NS grade C to NS grade B, which was more significant than results from previous studies involving standalone FOP labels. The interventions also reduced the amount of calories (12.86 kcal), total fat (1.21g), saturated fat (0.85g), sugar (0.82g) and sodium (156.64mg) purchased.

Notably, the researchers found that shopping with the four digital features led to healthier food choices across all three orders.

Assistant Professor Soye Shin from Duke-NUS’ Health Services and Systems Research Programme, the study’s first author, said of the findings: “As online grocery shopping is rapidly gaining ground, we wanted to see if we could design low cost, scalable online tools that could be used to nudge consumers toward healthier choices at the point of purchase. These results show the potential of these tools to improve diet and health outcomes.”

These findings underscore the advantages of introducing diet quality labels, such as Singapore’s Nutri-Grade labelling initiative, which currently only includes beverages but is planned to expand to other food categories.

Senior author Professor Eric Finkelstein, from Duke-NUS’ Health Services and Systems Research Programme, said: “These results are encouraging but the next step is to work with retailers to incorporate these features into existing online stores. Only then will the full value of this approach be realised.”

Next, the researchers will expand the study to include consumers of low socio-economic status and little nutritional knowledge. They will also investigate if the multi-pronged intervention strategy has the potential to positively impact consumers’ health in the long term.

Professor Patrick Tan, Senior Vice-Dean for Research at Duke-NUS, commented on the study’s impact: “This study reflects how smart, evidence-based interventions—when applied at the right moment—can empower people to make better everyday choices for their health. It also shows how research can lead to practical tools that improve not just individual choices, but population health outcomes.”

Duke-NUS is at the forefront of biomedical research and translational innovations. This new study is part of the School’s ongoing efforts to improve global health through systems research and scientific breakthroughs.

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DOI: 10.1016/j.amepre.2025.03.002

About Duke-NUS Medical School

Duke-NUS is Singapore’s flagship graduate entry medical school, established in 2005 with a strategic, government-led partnership between two world-class institutions: Duke University School of Medicine and the National University of Singapore (NUS). Through an innovative curriculum, students at Duke-NUS are nurtured to become multi-faceted ‘Clinicians Plus’ poised to steer the healthcare and biomedical ecosystem in Singapore and beyond. A leader in ground-breaking research and translational innovation, Duke-NUS has gained international renown through its five Signature Research Programmes and ten Centres. The enduring impact of its discoveries is amplified by its successful Academic Medicine partnership with Singapore Health Services (SingHealth), Singapore’s largest healthcare group. This strategic alliance has led to the creation of 15 Academic Clinical Programmes, which harness multi-disciplinary research and education to transform medicine and improve lives.   

For more information, please visit www.duke-nus.edu.sg

[1] Nutri-Score is a nutritional rating system that assigns points to a food product based on the amounts of negative ingredients (energy, sugar, sodium and saturated fat) and positive ingredients (fruits/vegetables, protein and dietary fibre) it contains. The difference between the sum of points for negative ingredients and the sum of points for positive ingredients becomes the final score, which is converted to a letter grade.