IntroductionPoor diet is a leading risk factor for non-communicable diseases and costs the National Health Service £5.8 billion annually. Product placement strategies used extensively in food outlets, like supermarkets, can influence customers’ preferences. Policy-makers, including the UK Government, are considering legislation to ensure placement strategies promote healthier food purchasing and dietary habits. High-quality scientific evidence is needed to inform future policy action. This study will assess whether healthier placement strategies in supermarkets improve household purchasing patterns and the diets of more than one household member.Methods and analysesThis natural experiment, with a prospective matched controlled cluster design, is set in discount supermarkets across England. The primary objective is to investigate whether enhanced placement of fresh fruit and vegetables improves household-level purchasing of these products after 6 months. Secondary objectives will examine: (1) differences in intervention effects on purchasing by level of educational attainment, (2) intervention effects on the dietary quality of women and their young children, (3) intervention effects on store-level sales of fruit and vegetables and (4) cost-effectiveness of the intervention from individual, retailer and societal perspectives. Up to 810 intervention and 810 control participants will be recruited from 18 intervention and 18 matched control stores. Eligible participants will be women aged 18–45 years, who hold a loyalty card and shop in a study store. Each control store will be matched to an intervention store on: (1) sales profile, (2) neighbourhood deprivation and (3) customer profile. A detailed process evaluation will assess intervention implementation, mechanisms of impact and, social and environmental contexts.Ethics and disseminationEthical approval was obtained from the University of Southampton, Faculty of Medicine Ethics Committee (ID 20986.A5). Primary, secondary and process evaluation results will be submitted for publication in peer-reviewed scientific journals and shared with policy-makers.Trial registration numberNCT03573973.

Objectives To examine women’s perceptions of factors that influence their food shopping choices, particularly in relation to store layout, and their views on ways that supermarkets could support healthier choices. Design This qualitative cross-sectional study used semi-structured telephone interviews to ask participants the reasons for their choice of supermarket and factors in-store that prompted their food selections. The actions supermarkets, governments and customers could take to encourage healthier food choices were explored with women. Thematic analysis was conducted to identify key themes. Setting Six supermarkets across England. Participants Twenty women customers aged 18–45 years. Results Participants had a median age of 39.5 years (IQR: 35.1, 42.3), a median weekly grocery spend of £70 (IQR: 50, 88), and 44% had left school aged 16 years. Women reported that achieving value for money, feeling hungry, tired, or stressed, and meeting family members’ food preferences influenced their food shopping choices. The physical environment was important, including product quality and variety, plus ease of accessing the store or products in-store. Many participants described how they made unintended food selections as a result of prominent placement of unhealthy products in supermarkets, even if they adopted more conscious approaches to food shopping (i.e. written or mental lists). Participants described healthy eating as a personal responsibility, but some stated that governments and supermarkets could be more supportive. Conclusions This study highlighted that in-store environments can undermine intentions to purchase and consume healthy foods. Creating healthier supermarket environments could reduce the burden of personal responsibility for healthy eating, by making healthier choices easier. Future research could explore the interplay of personal, societal and commercial responsibility for food choices and health status.