Increased Proportion of Lower Energy Density Items vs. Nutritional Labelling at an Online Supermarket

Effectiveness of Information-based Versus Structural Interventions on Food Choices by Socioeconomic Position: a Randomized Controlled Trial in an Experimental Online Supermarket

This study will be a 2x2 randomised controlled trial with information-based intervention (no labelling / labelling) and structural intervention (default proportion / increased proportion of lower energy density food items) as between-subject factors and energy density (kcal/g) of food purchases during an online supermarket-shopping task as dependent variable. This study will use an online supermarket platform developed to mimic an online supermarket website and participants will be asked to complete a shopping task using a pre-determined shopping list of 10 items.

Study Overview

• Status: Completed
• Conditions: Diet, Healthy; Food Selection
• Intervention / Treatment: Behavioral: Labelling; Behavioral: Increased proportion of lower energy density items

Detailed Description

See attached protocol documents.

• Study Type: Interventional
• Enrollment (Actual): 1000
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Merseyside
    • Liverpool, Merseyside, United Kingdom, L69 7ZA
      • University of Liverpool

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• United Kingdom residents
• Aged ≥ 18 years
• Fluent in English
• Have access to a computer and Internet
• Responsible for a substantial proportion of household grocery shopping

Exclusion Criteria:

• Unable to provide informed consent and to comply with the study requirements
• Any dietary restriction (vegetarian, vegan, gluten-free, sugar-free, dairy or lactose free, food allergy, other)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Default proportion & no labelling; No intervention: Default proportion condition (33% lower energy density items - 67% higher energy density items). Lower energy density items will be defined as lower ED ≤ median of ED distribution within a food category. No labelling.
Experimental: Default proportion & labelling; When energy density of a food item ≤ median of energy density distribution within a food category, "healthier choice" badges will be added to the food item pictures on the online supermarket. Instructions will introduce the badges to the participants as "In the online supermarket, the green tick allows you to see which products (e.g. muesli) in each product category (e.g. cereals) are healthier choices with fewer calories per gram than most other products in the same category."	Behavioral: Labelling; When energy density of an item ≤ median of ED distribution within a food category, "healthier choice" badges will be added to the food item pictures on the online supermarket. Instructions when logging-into the platform will introduce the badges to the participants: "In the online supermarket, the green tick allows you to see which products (e.g. muesli) in each product category (e.g. cereals) are healthier choices with fewer calories per gram than most other products in the same category."
Experimental: Increased proportion & no labelling; The proportion of lower energy density items vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (33% lower - 67% higher). Lower energy density items will be defined as lower ED ≤ median of ED distribution within a food category.	Behavioral: Increased proportion of lower energy density items; The proportion of lower energy density vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (D and DL) (33% lower - 67% higher). Lower energy density items will be defined as lower energy density ≤ median of energy density distribution within a food category.
Experimental: Increased proportion & labelling; The proportion of lower energy density items vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (33% lower - 67% higher). Lower energy density items will be defined as lower ED ≤ median of ED distribution within a food category. When energy density of a food item ≤ median of energy density distribution within a food category, "healthier choice" badges will be added to the food item pictures on the online supermarket. Instructions will introduce the badges to the participants as "In the online supermarket, the green tick allows you to see which products (e.g. muesli) in each product category (e.g. cereals) are healthier choices with fewer calories per gram than most other products in the same category."	Behavioral: Labelling; When energy density of an item ≤ median of ED distribution within a food category, "healthier choice" badges will be added to the food item pictures on the online supermarket. Instructions when logging-into the platform will introduce the badges to the participants: "In the online supermarket, the green tick allows you to see which products (e.g. muesli) in each product category (e.g. cereals) are healthier choices with fewer calories per gram than most other products in the same category."; Behavioral: Increased proportion of lower energy density items; The proportion of lower energy density vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (D and DL) (33% lower - 67% higher). Lower energy density items will be defined as lower energy density ≤ median of energy density distribution within a food category.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean ED of the food items purchased (kcal/100g)	Calculated as the sum of the energy of the purchased items (kcal) divided by the sum of their weight (g) and multiplied by 100.	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total energy of the food items purchased (kcal)	Calculated as the sum of the energy of the purchased items (kcal)	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)
Energy from total sugar (% of total energy)	Calculated as the percentage of total energy of the purchased items from total sugar	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)
Energy from saturated fatty acids (SFA) (% of total energy)	Calculated as the percentage of total energy of the purchased items from SFA	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)
Salt content (g/100g)	Calculated as the sum of the salt content of the purchased items (g) divided by the sum of their weight (g) and multiplied by 100.	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)
Proportion of lower energy density food items in the basket of foods purchased	Lower energy density items will be defined as ≤ median of energy density distribution within a food category	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)
Cost (GPB)	Calculated as the sum of the prices of the purchased items	20 minutes (the time frame denotes time taken to make the food shopping task online and there is no follow up)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Validity	Mean of item "I would normally buy [the 10 items on the shopping list]" for all the food items coded as: 1 = Never; 2 = Very rarely; 3 = Rarely; 4 = Occasionally; 5 = Frequently; 6 = Very frequently.	5 minutes (the time frame denotes time taken to fill in the debriefing questionnaire and there is no follow up)
Kcal influence	Answer to the item "The choices I made during online shopping were influenced by how many calories I thought were in the options available." coded as: 1 = Strongly disagree; 2 = Disagree; 3 = Slightly disagree; 4 = Neutral; 5 = Slightly agree; 6 = Agree; 7 = Strongly agree	5 minutes (the time frame denotes time taken to fill in the debriefing questionnaire and there is no follow up)

Collaborators and Investigators

• Sponsor: University of Liverpool

Study record dates

Study Major Dates

• Study Start (Actual): April 13, 2020
• Primary Completion (Actual): April 13, 2020
• Study Completion (Actual): May 13, 2020

Study Registration Dates

• First Submitted: April 7, 2020
• First Submitted That Met QC Criteria: April 7, 2020
• First Posted (Actual): April 10, 2020

Study Record Updates

• Last Update Posted (Actual): November 3, 2020
• Last Update Submitted That Met QC Criteria: November 2, 2020
• Last Verified: November 1, 2020

More Information

Terms related to this study

• Keywords: availability; labelling; food choice; socio-economic position
• Other Study ID Numbers: 803194 1B3

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Yes
• IPD Plan Description: Shared on the Open Science Framework
• IPD Sharing Time Frame: On publication, indefinitely
• IPD Sharing Access Criteria: Open website
• IPD Sharing Supporting Information Type: Study Protocol; Statistical Analysis Plan (SAP); Informed Consent Form (ICF)

Study Data/Documents

1. Study Protocol
2. Statistical Analysis Plan
3. Informed Consent Form
4. Individual Participant Data Set
   Information comments: When results will be published

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No