Food Swaps to Improve the Healthfulness and Reduce the Carbon Footprint of Grocery Purchases
NCT ID: NCT06648226
Last Updated: 2025-07-22
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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COMPLETED
NA
1201 participants
INTERVENTIONAL
2025-05-07
2025-06-25
Brief Summary
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Detailed Description
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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.
Conditions
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Study Design
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RANDOMIZED
PARALLEL
PREVENTION
NONE
Study Groups
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Health swaps
Labels will be "nutrition grades" for products and replacement swap suggestions will be for items with a better nutrition grade.
Health swaps
Participants will view "health grade" labels on all products in the online grocery store indicating their healthfulness as estimated by United Kingdom Ofcom Nutrient Profiling Model scores. The health score labels will mimic Nutri-Score labels, a labeling system used in some European countries, showing a color-coded grade of "A" (green) through "F" (red) on each product. Products with "A" and "B" labels will meet the United Kingdom's cutoff for products that can be marketed to children and "C", "D" and "F" labels products are less healthy than this cutoff (based on tertiles of Ofcom scores within each food group). When participants attempt to add a less healthy product to their cart (e.g., "C," "D" or "F" health label), the store will automatically suggest a healthier product from the same category (e.g., with a "A" or "B" health label).
Climate swaps
Labels will be "climate grades" for products and replacement swap suggestions will be for items with a better climate grade.
Climate swaps
Participants will view "climate grade" labels on all products indicating their climate impact. The climate impact is calculated as the greenhouse gas emissions associated with producing the product in carbon dioxide equivalents (CO2-eq) per 100g (i.e., "carbon footprint"). Labels will be applied based on quintiles of carbon footprints in each food group. When participants attempt to add a high-climate-impact product to their cart (e.g., with a "C," "D," or "F" climate label), the store will automatically offer them swaps to more climate-friendly products (e.g., with a "A" or "B" climate label).
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.
Combined health and climate swaps
Participants will view both the health and climate grade labels on all products in the online grocery store. When participants attempt to select a product with a "C," "D," or "F" label on either dimension to their cart, the store will automatically offer them swaps to products that offer improvement over the original food on at least 1 dimension (health or climate-friendliness) and were at least as good or better on the other dimension, with the additional guardrail that the store never suggests products with a "C," "D" or "F" label on either dimension.
Control
No labels or swaps.
Control
Participants will not view any extra labels or be offered any swaps in the online grocery store.
Interventions
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Health swaps
Participants will view "health grade" labels on all products in the online grocery store indicating their healthfulness as estimated by United Kingdom Ofcom Nutrient Profiling Model scores. The health score labels will mimic Nutri-Score labels, a labeling system used in some European countries, showing a color-coded grade of "A" (green) through "F" (red) on each product. Products with "A" and "B" labels will meet the United Kingdom's cutoff for products that can be marketed to children and "C", "D" and "F" labels products are less healthy than this cutoff (based on tertiles of Ofcom scores within each food group). When participants attempt to add a less healthy product to their cart (e.g., "C," "D" or "F" health label), the store will automatically suggest a healthier product from the same category (e.g., with a "A" or "B" health label).
Climate swaps
Participants will view "climate grade" labels on all products indicating their climate impact. The climate impact is calculated as the greenhouse gas emissions associated with producing the product in carbon dioxide equivalents (CO2-eq) per 100g (i.e., "carbon footprint"). Labels will be applied based on quintiles of carbon footprints in each food group. When participants attempt to add a high-climate-impact product to their cart (e.g., with a "C," "D," or "F" climate label), the store will automatically offer them swaps to more climate-friendly products (e.g., with a "A" or "B" climate label).
Combined health and climate swaps
Participants will view both the health and climate grade labels on all products in the online grocery store. When participants attempt to select a product with a "C," "D," or "F" label on either dimension to their cart, the store will automatically offer them swaps to products that offer improvement over the original food on at least 1 dimension (health or climate-friendliness) and were at least as good or better on the other dimension, with the additional guardrail that the store never suggests products with a "C," "D" or "F" label on either dimension.
Control
Participants will not view any extra labels or be offered any swaps in the online grocery store.
Eligibility Criteria
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Inclusion Criteria
* Reside in the United States
* Able to complete a survey in English
* Have internet access to complete the 3 online study visits
Exclusion Criteria
* 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
18 Years
ALL
Yes
Sponsors
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National Heart, Lung, and Blood Institute (NHLBI)
NIH
Stanford University
OTHER
Responsible Party
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Anna Grummon
Assistant Professor
Principal Investigators
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Anna H. Grummon, PhD
Role: PRINCIPAL_INVESTIGATOR
Stanford School of Medicine
Locations
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Stanford School of Medicine
Palo Alto, California, United States
Countries
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Provided Documents
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Document Type: Statistical Analysis Plan
Other Identifiers
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76925
Identifier Type: -
Identifier Source: org_study_id
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