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

NCT06648226 | Completed

• 2 other identifiers: 76925K01HL158608
• Study Type: interventional
• Target: 1,201
• Locations: 1 country
• Sites: 1

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.

Conditions

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

Keywords

food choices; climate; dietary substitutions; diet

Outcome Measures

Primary Outcomes (2)

• Healthfulness of product selection

  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.

  Assessed at baseline, 1-week follow-up, and 2-week follow-up

• Carbon footprint of participants' grocery store selections

  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.

  Assessed at baseline, 1-week follow-up, and 2-week follow-up

Secondary Outcomes (16)

• 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

• 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

Other Outcomes (12)

• Perceived helpfulness of nutrition labels

  Assessed at 2-week follow-up

• Perceived helpfulness of climate labels

  Assessed at 2-week follow-up

• Perceived helpfulness of health swap recommendations

  Assessed at 2-week follow-up

Study Arms (4)

Health swaps

EXPERIMENTAL

Labels will be "nutrition grades" for products and replacement swap suggestions will be for items with a better nutrition grade.

Behavioral: Health swaps

Climate swaps

EXPERIMENTAL

Labels will be "climate grades" for products and replacement swap suggestions will be for items with a better climate grade.

Behavioral: Climate swaps

Combined health and climate swaps

EXPERIMENTAL

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.

Behavioral: Combined health and climate swaps

Control

ACTIVE COMPARATOR

No labels or swaps.

Behavioral: Control

Interventions

Health swaps BEHAVIORAL

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).

Health swaps

Climate swaps BEHAVIORAL

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).

Climate swaps

Combined health and climate swaps BEHAVIORAL

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.

Combined health and climate swaps

Control BEHAVIORAL

Participants will not view any extra labels or be offered any swaps in the online grocery store.

Control

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Stanford University: lead
• National Heart, Lung, and Blood Institute (NHLBI): collaborator

Study Sites (1)

Stanford School of Medicine

Palo Alto, California, 94304, United States

Location

MeSH Terms

Conditions

Food Preferences; Feeding Behavior

Condition Hierarchy (Ancestors)

Behavior; Behavior, Animal

Study Officials

• Anna H. Grummon, PhD

  Stanford School of Medicine

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: October 16, 2024
• First Posted: October 18, 2024
• Study Start: May 7, 2025
• Primary Completion: June 25, 2025
• Study Completion: June 25, 2025
• Last Updated: July 22, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: ANALYTIC CODE
• Time Frame: The analytic code will be posted to a public repository upon publication of study findings.
• Access Criteria: Publicly available without restrictions.

Locations

US (1)