Impact of increasing the relative availability of meat-free options on food selection: two natural field experiments and an online randomised trial

Rachel Pechey,Brian Cook,Susan A Jebb,Paul Bateman

doi:10.1186/s12966-021-01239-z

Rachel Pechey, Brian Cook + Show 2 more

Open Access

https://doi.org/10.1186/s12966-021-01239-z

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Abstract

BackgroundIncreasing the availability of lower energy-density foods is a promising intervention to encourage healthier food purchasing but few studies have examined the effect of increasing availability of meat-free meals to promote more sustainable purchasing. We report three studies, all examining the impact of altering the availability of meat-free meals on meal selection.MethodsStudy 1 (a natural experiment in one university cafeteria) examined the impact of altering the ratio of meat-free meals (one meat-free and two meat, to two meat-free and one meat) on weekly sales of meals containing meat. Study 2 (a natural experiment in 18 worksite cafeterias) examined the impact on meat-free meal sales of a menu change designed to increase the availability of meat-free meals. Study 3 (an online study of 2205 UK-representative adults) compared meal selections when participants were randomised to ranges comprised of (a) one meat-free, three meat options; (b) two meat-free, two meat; or (c) three meat-free, one meat.ResultsStudy 1 suggested a significant decrease in the proportion of sales of meat options when the availability of meat-free options increased (− 19.9 percentage points; 95%CIs:-25.2,-14.6), with no evidence of changes to meat-based meal sales in other university cafeterias during the same period. Findings from Study 2 were mixed: multilevel regressions found no evidence of an increase in meat-free meals following the menu change (2.3 percentage points; 95%CIs: − 1.3,5.9), while interrupted time-series analyses suggested sales did increase (2.3; 95%CIs: 0.4,4.2), but implementation of the planned change was limited. In Study 3 reducing meat-free options from 50 to 25% reduced participants’ selection of meat-free options (odds ratio 0.35; 95%CIs: 0.26,0.46), while increasing meat-free options from 50 to 75% increased meat-free selections (odds ratio 2.43; 95%CIs: 1.94,3.04). There was no evidence effects were moderated by gender, socioeconomic status or usual meat consumption.ConclusionIncreasing the availability of meat-free options is effective at reducing meat selection and purchasing for different ratios of meat to meat-free options. The magnitude of the effect is uncertain, but with no evidence of differences in response by demographic groups when directly tested.Trial registrationStudy 3: Open Science Framework; https://osf.io/ze9c6; 6/8/2020.

Highlights

Increasing the availability of lower energy-density foods is a promising intervention to encourage healthier food purchasing but few studies have examined the effect of increasing availability of meat-free meals to promote more sustainable purchasing
An experimental field study in one student cafeteria has suggested that increasing the percentage of vegetarian meals from 25 to 50% leads to an approximately 40% rise in vegetarian meal sales, with observational data from two further university cafeterias showing increased meat-free meal availability was associated with increased meat-free purchasing [9]
Study 1: natural experiment in a university cafeteria Impact on sales of meat‐based meals There was a 19.9 percentage point decrease (95%CIs:25.2, − 14.6) in the proportion of sales comprised by meat options in the intervention cafeteria when a greater proportion of available meals were meat-free

Summary

Introduction

Increasing the availability of lower energy-density foods is a promising intervention to encourage healthier food purchasing but few studies have examined the effect of increasing availability of meat-free meals to promote more sustainable purchasing. All examining the impact of altering the availability of meat-free meals on meal selection. One promising intervention is to alter the availability of meat vs meat-free meals. A recent Cochrane review found that altering the availability of a particular set of food options changes their selection [7], albeit with low overall certainty. A systematic review of the impact of interventions that aim to restructure physical microenvironments on selection of meat products did not identify any studies relating to increasing the availability of vegetarian food to reduce meat consumption [8]. An experimental field study in one student cafeteria has suggested that increasing the percentage of vegetarian meals from 25 to 50% leads to an approximately 40% rise in vegetarian meal sales, with observational data from two further university cafeterias showing increased meat-free meal availability was associated with increased meat-free purchasing [9]

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