A Randomized Trial of Food Swaps to Improve the Healthfulness and Reduce the Carbon Footprint of Grocery Purchases
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- Stanford University
- Enrollment
- 1,201
- Locations
- 2
- Primary Endpoint
- Healthfulness of product selection
Study Overview
Brief Summary
The study aims to determine whether viewing health or climate labels (or both) and receiving recommendations for healthier or more climate-friendly swaps (or both) in an online grocery store environment improves the healthfulness and reduces the carbon footprint of consumers' food and beverage purchases compared to shopping as usual without swap recommendations. The online store will record participants' food selections. Participants will also be asked to complete survey measures.
Detailed Description
Participants will complete an online between-subjects randomized experiment. The experiment will involve three study visits.
In the first study visit, participants will complete an online grocery store shopping task without intervention. Participants will be given a budget of $50 and asked to shop as they normally would. The store will record participants' food selections. After completing the shopping task, participants will complete an online survey.
Approximately one week later, participants will complete a second study visit with the same instructions. They will be randomized to 1 of 4 conditions (1) health only, 2) climate only, 3) combined health and climate, 4) control. In the health only condition, participants will view labels with nutrition grades and may be directed to swap their selections for healthier items. In the climate only condition, participants will view labels with climate grades and may be directed to swap their selections for more climate-friendly (lower-carbon-footprint) items. In the combined health and climate condition, participants will view labels with health and climate grades and may be directed to swap their selections for healthier or more climate-friendly items. In the control group, participants will not view any labels or swaps. The store will record participants' selections. After completing the shopping task, participants will complete an online survey.
In the third study visit, the participants will maintain their assigned group and will be asked to repeat the same tasks as in the second visit.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Prevention
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Aged 18 years or older
- •Reside in the United States
- •Able to complete a survey in English
- •Have internet access to complete the 3 online study visits
Exclusion Criteria
- •Under the age of 18
- •Reside outside of the United States
- •Unable to complete a survey in English
- •Do not have internet access to complete the 3 online study visits
Arms & Interventions
Health swaps
Labels will be "nutrition grades" for products and replacement swap suggestions will be for items with a better nutrition grade.
Intervention: Health swaps (Behavioral)
Climate swaps
Labels will be "climate grades" for products and replacement swap suggestions will be for items with a better climate grade.
Intervention: Climate swaps (Behavioral)
Combined health and climate swaps
Labels will be "nutrition grades" and "climate grades" for products and replacement swap suggestions will be for items that are better than originally selected products on at least one dimension (nutrition grade or climate grade) and not worse than originally selected products on either dimension.
Intervention: Combined health and climate swaps (Behavioral)
Control
No labels or swaps.
Intervention: Control (Behavioral)
Outcomes
Primary Outcomes
Healthfulness of product selection
Time Frame: Assessed at baseline, 1-week follow-up, and 2-week follow-up
The study will asses healthfulness of participants' selections as the average Ofcom Nutrient Profiling Model score of the products the participants select in the shopping task. The score ranges from 0 to 100, where higher scores are healthier.
Carbon footprint of participants' grocery store selections
Time Frame: Assessed at baseline, 1-week follow-up, and 2-week follow-up
The study will assess the carbon footprint of participants' selections, operationalized as the average carbon footprint (in CO2-equivalents) of the products the participants select in the shopping task.
Healthfulness of Product Selection
Time Frame: 1-week follow-up (visit 2), and 2-week follow-up (visit 3)
The study will asses healthfulness of participants' selections as the average Ofcom Nutrient Profiling Model score of the products the participants select in the shopping task. The score ranges from 0 to 100, where higher scores are healthier. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, data from the non-missing visit was used.
Carbon Footprint of Participants' Grocery Store Selections
Time Frame: 1-week follow-up (visit 2), and 2-week follow-up (visit 3)
The study will assess the carbon footprint of participants' selections, operationalized as the average carbon footprint (in CO2-equivalents) of the products the participants select in the shopping task. Outcome values were calculated as each participant's mean across visits 2 and 3. If participants had missing data at one of these visits, the non-missing value was used.
Secondary Outcomes
- Saturated fat density of participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Fiber density of participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Protein density of participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Total spending on participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Calorie density of participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Sugar density of participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Sodium density of participants' grocery selections(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Thinking about health(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Thinking about climate impact(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Thinking about taste(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Injunctive norms to buy foods with low climate impact(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Descriptive norms to buy foods with low climate impact(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Calorie Density of Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Sugar Density of Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Sodium Density of Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Saturated Fat Density of Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Fiber Density of Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Protein Density of Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Total Spending on Participants' Grocery Selections(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Thinking About Health(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Thinking About Climate Impact(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Thinking About Taste(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Negative Emotional Reactions While Shopping(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Positive Emotional Reactions While Shopping(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Injunctive Norms to Buy Healthy Foods(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Descriptive Norms to Buy Healthy Foods(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Injunctive Norms to Buy Foods With Low Climate Impact(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Descriptive Norms to Buy Foods With Low Climate Impact(1-week follow-up (visit 2), and 2-week follow-up (visit 3))
- Descriptive norms to buy healthy foods(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Injunctive norms to buy healthy foods(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Negative emotional reactions while shopping(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
- Positive emotional reactions while shopping(Assessed at baseline, 1-week follow-up, and 2-week follow-up)
Investigators
Anna Grummon
Assistant Professor
Stanford University