SALIENT Food Trials

THE PROBLEM

Fruit and vegetable consumption in the UK is below recommended levels, with only one third of adults consuming at least five portions per day. Fruit and vegetable consumption patterns are not equal around the country, and less wealthy households tend to consume fewer portions per day. Low consumption of fruit and vegetables is associated with increased risk of non-communicable diseases, including cancer and cardiovascular disease.

The high cost of fruits and vegetables has been identified by consumers as a barrier to increasing their consumption. To address this issue, studies have investigated whether applying price promotions to fruits and vegetables leads to an increase in their purchasing or consumption, and the majority have found them to be effective in doing so.

However, the current evidence base consists mostly of hypothetical modelling studies, real-world implementation studies with only a small sample of stores, or studies specifically focused on lower socio-economic groups. The current study will investigate the effectiveness of fruit and vegetable discounts across a large sample of stores belonging to a UK-based retailer, varying in their size, location and socio-economic status.

RESARCH QUESTION

1. What is the impact on sales of price discounts on fruit and vegetables?

2. Does the impact of price discounts vary by the size, location or socio-economic status of the store?

LATEST UPDATE

Learn about the latest update on our trial here (PDF).

THE INTERVENTION

The implementation of a loyalty card programme which provides enlisted customers with discounts on select products, including fruit and vegetables.

PRELIMINARY OR PILOT STUDIES

A pilot study analysed data on aggregate sales of fruit and vegetables for loyalty card holders and non-loyalty card holders from two stores over a two year period. The purpose of the pilot was to observe patterns in the dataset, isolate key variables associated with changes in trend, and design Interrupted Time Series models that we will use in our evaluation. Using the pilot analysis, we were able to answer any questions that may also be true of the full dataset, to inform the drafting of a research protocol for this study.

EVALUATION DESIGN

An Interrupted Time Series analysis will assess the effect of introducing loyalty card price discounts on fruits and vegetables, on their weekly sales. This quasi-experimental design will track the trend in weekly fruit and vegetable sales over a two-year period (June 2022 to June 2024), and compare the trends before and after the introduction of the loyalty card programme. The weekly sales data will be divided into purchases made with a loyalty card and purchases made without, with the latter acting as a comparator series. This approach will allow for the evaluation of how effective the loyalty card pricing of fruits and vegetables was in encouraging customers to purchase more of these products, and whether these effects were specific to those enrolled in the loyalty card programme. We will assess differences in effect size by store size, socio-economic status and location.

KEY STAKEHOLDERS

Community Shop management, staff, and members.

TARGET POPULATION

Individuals facing economic hardship.