NCT06648226

Food Swaps to Improve the Healthfulness and Reduce the Carbon Footprint of Grocery Purchases

A Randomized Trial of Food Swaps to Improve the Healthfulness and Reduce the Carbon Footprint of Grocery Purchases

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 1,201 (actual)
• Sponsor: Stanford University · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Accepted

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.

Conditions

• Food Selection
• Nutrition
• Food Preferences
• Dietary Habits
• Sustainability
• Healthy Diet

Interventions

Type	Name	Description
BEHAVIORAL	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).
BEHAVIORAL	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).
BEHAVIORAL	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.
BEHAVIORAL	Control	Participants will not view any extra labels or be offered any swaps in the online grocery store.

Timeline

• Start date: 2025-05-07
• Primary completion: 2025-06-25
• Completion: 2025-06-25
• First posted: 2024-10-18
• Last updated: 2025-07-22

Locations

1 site across 1 country: United States