A Randomized Trial Using an Online Grocery Store to Evaluate a Multicomponent Digital Intervention to Improve Diet Quality.

Introduction: Poor diet is a key contributor to rising rates of noncommunicable diseases. This study tested the ability of an online grocery store that includes a multicomponent digital intervention identified through the Multiphase Optimization Strategy to improve the nutritional quality of shopper's purchases.

Study Design: This was a 2-arm RCT.

Setting/participants: A convenience sample of online grocery shoppers in Singapore who were the primary shoppers for their household were recruited through advertisements on Facebook and Instagram (n=328). Data were collected between January and October 2023.

Intervention: Participants were randomized into 1 of 2 versions of the online grocery store and asked to complete 3 weekly orders delivered to their homes. The arms were (1) an online store with no intervention (control) and (2) the same online store with the multicomponent intervention, including (i) interpretive front-of-package nutrition labels, (ii) real-time feedback on the nutritional quality of the grocery cart, (iii) ordering of healthier products first, and (iv) offering healthier substitutes for shoppers' chosen products.

Main Outcome Measures: The primary outcome was the weighted (by number of servings) average Nutri-Score points of the grocery cart. Secondary outcomes included the weighted average calories and select nutrients (sugar, sodium, total fat, and saturated fat) per serving. These outcomes were analysed using a linear mixed-effects model.

Results: The multicomponent intervention led to a statistically significant 4.06-point (95% CI=3.06, 5.07) increase in the weighted average Nutri-Score of the grocery cart relative to control, which equates to improving the nutritional quality of the cart from Nutri-Score Grade C (30-37 points) to B (37.1-40 points). The positive intervention effects were sustained across the 3 shopping experiences.

Conclusions: The multicomponent intervention improved the nutritional quality of online grocery carts over repeated orders, highlighting the potential of digital interventions to improve diet quality.

Trial Registration: This study is registered at www.

Clinicaltrials: gov NCT05537337.