Journal Article

P81 The use of eco-labels and price discounts to promote more sustainable online grocery purchases in the UK: a randomised controlled trial

Scarborough, Peter, Clark, Michael, White, Martin, Yu, Hao, Borzadaran Hamideh Mohtashami, Rens, Thijs van, Marteau Theresa, Adams, Jean, Kumar Anoushka, Thompson, Claire, Brock, Jessica, Oyinlola, Oyebode, Hillier, Edward, Bentil Helena

2025

Overview

BackgroundOur food system plays an important role in environmental degradation. Effective interventions are needed to promote sustainable food choices. Online grocery shops offer a way to study and evaluate these on a large scale. This study examines the impact of eco-labels and price discounts on the sustainability of grocery purchases in a real UK online supermarket using a customised browser extension.MethodsParticipants recruited from the UK Prolific panel were randomly assigned to one of six groups in a 2 × 3 factorial design. The interventions were (i) eco-labels, displaying the environmental impact of products on a scale of A (best) to G (worst), and (ii) price discounts (£1, £0.50, or no discount) offered on more sustainable alternative products for <3 items in participants’ baskets. The alternative products offered were randomly selected from a list created by the research team; they were more sustainable than selected products, usually priced within £2 of the selected products, and with an equal or better nutritional profile according to their traffic light labelling. The primary outcome was the average eco-score of purchased products, with lower scores indicating more sustainability. Preliminary results are based on data from 1431 participants recruited in 5 waves between April 2024 and November 2024 and who completed >1 shop in the 8-week period they were enrolled in the study. Additional data collection will be on-going until April 2025. Regression analysis was used to test the effectiveness of the interventions.ResultsInitial findings suggest that eco-labels have a negligible effect on the sustainability of grocery purchases (b = 0.04, SE = 0.43, p= 0.92). Price discounts may improve the sustainability of purchases if sufficiently large (for £1 discount: b = -0.90, SE = 0.49, p= 0.07). There may be an interaction between the interventions; there is a greater effect of price discounts in the group where eco-labels are visible (b = -1.53, p= 0.03). Further analysis will explore the mechanisms driving these effects, including consumer acceptance of alternatives and willingness to pay for more sustainable products. We will also examine the potential impact of the interventions on nutrition and health outcomes.ConclusionPrice incentives may be a more promising way to promote sustainable online grocery purchases than eco-labels alone. Policy interventions such as subsidies or taxes may be more impactful than information-based approaches alone.

• Publisher: BMJ Publishing Group LTD
• Subject: Data collection / Discounts / Environmental degradation / Environmental impact / Environmental labelling / Food systems / Green products / Regression analysis / Sustainability