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

Study Overview
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Brief Summary
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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.

Detailed Description
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See attached protocol documents.

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

Conditions
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Diet, Healthy, Food Selection

Intervention / Treatment
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* Behavioral: Increased proportion of lower energy density items
* Behavioral: Labelling


Participation Criteria
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Eligibility Criteria
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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)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Default proportion & no labelling<br>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<br>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<br>* 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.<br>|
| Experimental: Increased proportion & no labelling<br>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<br>* 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.<br>|
| Experimental: Increased proportion & labelling<br>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: Increased proportion of lower energy density items<br>* 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.<br>Behavioral: Labelling<br>* 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.<br>|

What is the study measuring?
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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) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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availability, labelling, food choice, socio-economic position