Impact of increasing the availability of healthier vs. less-healthy food on food selection: a randomised laboratory experiment

Pechey, Rachel; Sexton, Olivia; Codling, Saphsa; Marteau, Theresa M.

Abstract

Background
Environmental cues shape behaviour, but few studies compare the impact of targeting healthier vs. less-healthy cues. One online study suggested greater impact on selection from increasing the number of less-healthy (vs. healthier) snacks. The current study aimed to: (1) extend the previous study by using physically-present snacks for immediate consumption; (2) explore responsiveness by socio-economic position; (3) investigate possible mediators (response inhibition, food appeal) of any socio-economic differences in selection.

Methods
In a between-subjects laboratory experiment UK adults (n = 417) were randomised according to their ID number (without blinding) to one of three ranges of options: Two healthier, two less-healthy [“Equal”] (n = 136); Six healthier, two less-healthy [“Increased Healthier”] (n = 143); Two healthier, six less-healthy [“Increased Less-Healthy”] (n = 138). Participants completed measures of response inhibition and food appeal, and selected a snack for immediate consumption from their allocated range. The primary outcome was selection of a healthier (over less-healthy) snack.

Results
The odds of selecting a less-healthy snack were 2.9 times higher (95%CIs:1.7,5.1) in the Increased Less-Healthy condition compared to the Equal condition. The odds of selecting a healthier snack were 2.5 times higher (95%CIs:1.5,4.1) in the Increased Healthier (vs. Equal) condition. There was no significant difference in the size of these effects (− 0.2; 95%CIs:-1.1,0.7). Findings were inconclusive with regard to interactions by education, but the direction of effects was consistent with potentially larger impact of the Increased Healthier condition on selection for higher-educated participants, and potentially larger impact of the Increased Less-Healthy condition for less-educated participants.

Conclusions
A greater impact from increasing the number of less-healthy (over healthier) foods was not replicated when selecting snacks for immediate consumption: both increased selections of the targeted foods with no evidence of a difference in effectiveness. The observed pattern of results suggested possible differential impact by education, albeit not statistically significant. If replicated in larger studies, this could suggest that removing less-healthy options has the potential to reduce health inequalities due to unhealthier diets. Conversely, adding healthier options could have the potential to increase these inequalities.

Citation

Pechey, R., Sexton, O., Codling, S., & Marteau, T. M. (2021). Impact of increasing the availability of healthier vs. less-healthy food on food selection: a randomised laboratory experiment. BMC public health, 21(1), Article 132. https://doi.org/10.1186/s12889-020-10046-3

• Journal Article Type: Article
• Acceptance Date: Dec 10, 2020
• Online Publication Date: Feb 1, 2021
• Publication Date: 2021-12
• Deposit Date: Aug 16, 2021
• Publicly Available Date: Aug 16, 2021
• Journal: BMC Public Health
• Print ISSN: 1471-2458
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 1
• Article Number: 132
• DOI: https://doi.org/10.1186/s12889-020-10046-3
• Keywords: Absolute-and-relative availability; Food selection; Socioeconomic position; Health inequalities; Response inhibition; Food appeal
• Public URL: https://hull-repository.worktribe.com/output/3792140