Linguistically Tailored Health Messages to Encourage Plant-Based Food Choices in Adolescents

NCT06742346 | Enrolling By Invitation

• 2 other identifiers: ETH2324-0592VI.C.181.045
• Study Type: interventional
• Target: 600
• Locations: 2 countries
• Sites: 2

Brief Summary

The goal of this clinical trial is to investigate the effectiveness of linguistically tailored messages for promoting plant-based food choices in adolescents. The main question it aims to answer is: • Are linguistically tailored messages more effective in promoting plant-based eating compared to a) non-tailored messages (active control), and b) not receiving messages at all (passive control)? Researchers will compare participants exposed to linguistically tailored messages, non-tailored messages, and no messages to determine if linguistic messages are more effective in promoting plant-based food choices. Participants will receive daily messages promoting a plant-based diet from Monday to Friday for two weeks, accompanied by daily and weekend surveys about their food choices and message perception.

Conditions

Food Consumption; Sustainable Food Consumption; Sustainable Healthy Eating Behaviour

Keywords

Plant-based food; Sustainable healthy eating behavior; Large Language Models; Linguistically tailored messages; Adolescents

Outcome Measures

Primary Outcomes (3)

• Dietary behavior

  Participants will be asked to report their dietary behavior from the previous day. They will describe what they ate for lunch at school (open-ended question) and indicate whether the lunch was plant-based. Weekly measures will assess the frequency of plant-based meals and snacks over the past week. Participants will report how many days they consumed a plant-based breakfast, lunch, and dinner (response options: 0-7 days) and the number of plant-based snacks they had per day (response options: 0-6+ servings).

  From the start of the intervention week (baseline survey) to the end of the intervention, after two weeks.

• Attitude

  Attitude is measured by four items value, usefulness, pleasantness and interest. Question: When you think about plant-based eating (vegetarian or vegan), how would you rate plant-based eating on… 1. Value? Response options: 1) Worthless; 2) Somewhat Worthless; 3) Somewhat Valuable; 4) Valuable 2. Usefulness? Response options: 1) Useless; 2) Somewhat Useless; 3) Somewhat Useful; 4) Useful 3. Pleasantness? Response options: 1) Unpleasant; 2) Somewhat Unpleasant; 3) Somewhat Pleasant; 4) Pleasant 4. Interest? Response options: 1) Boring; 2) Somewhat Boring; 3) Somewhat Interesting; 4) Interesting. The items will be aggregated into a single composite score.

  During the intervention at the end of week 1 and week 2.

• Behavioral intention

  Question: How often do you plan to eat plant-based (either vegetarian or vegan) within the next week in situations where you can freely choose? Response options: 1) Never; 2) Rarely; 3) Sometimes; 4) Often

  During the intervention at the end of week 1 and week 2.

Secondary Outcomes (11)

• Perceived Source Similarity

  During the intervention at the end of week 1 and week 2.

• Source Liking

  During the intervention at the end of week 1 and week 2.

• Source Trust

  During the intervention at the end of week 1 and week 2.

• Message Liking

  During the intervention, daily (Monday-Friday) for two weeks.

• Message Shareability

  During the intervention, daily (Monday-Friday) for two weeks.

Other Outcomes (12)

• Exposure Time

  During the intervention, daily (Monday-Friday) for two weeks.

• Privacy Self-efficacy

  At baseline, before the start of the intervention.

• Perceived Ability to Control

  At baseline, before the start of the intervention.

Study Arms (4)

1: Passive control

NO INTERVENTION

Participants will receive no messages throughout the study.

2: Non-tailored messages

ACTIVE COMPARATOR

"Participants will receive non-tailored messages throughout the entire two weeks."

Behavioral: Non Tailored Messages

3: Linguitically tailored messages

EXPERIMENTAL

Participants will receive linguistically tailored messages throughout the entire two weeks.

Behavioral: Linguistically tailored health messages

4: Crossover arm

EXPERIMENTAL

Participants will receive both non-tailored and linguistically tailored messages for one week each.

Behavioral: Non Tailored Messages; Behavioral: Linguistically tailored health messages

Interventions

Non Tailored Messages BEHAVIORAL

Generic messages promoting a plant-based diet were developed, with each message addressing one of the three most commonly mentioned motives for plant-based eating (Miki et al., 2019; Miki et al., 2020): health motives, environmental motives, and animal welfare motives. All messages were designed to be factual (including science-based statistics), concise (4-5 sentences), relevant to teens (e.g., addressing health concerns like acne), and autonomy-supportive (offering suggestions and tips rather than directives) (Hingle et al., 2013). The messages were intentionally crafted in a neutral linguistic style, avoiding highly emotive language, non-standard syntax, or emojis. These messages are delivered from Monday to Friday for two weeks.

2: Non-tailored messages; 4: Crossover arm

Linguistically tailored health messages BEHAVIORAL

Linguistically tailored messages are generated using a Large Language Model. Generic messages promoting a plant-based diet were customized to align with participants' linguistic style, including their preferred choice of words, expressed valence, syntax, and emoji use. These messages are delivered from Monday to Friday for two weeks.

3: Linguitically tailored messages; 4: Crossover arm

Eligibility Criteria

• Age: 11 Years - 16 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• Aged 11-16 years
• Residing in the UK or Ireland
• Having access to plant-based food options during school hours (e.g., provided by the school, purchased, or brought from home or a store)

You may not qualify if:

• Adolescents who follow a strict vegetarian or vegan diet

Sponsors & Collaborators

• Erasmus University Rotterdam: lead

Study Sites (2)

Norstat UK Ltd. (Online Research Panel)

London, Ireland

Location

Norstat UK Ltd. (Online Research Panel)

London, United Kingdom

Location

Related Publications (5)

• Strecher VJ, McClure J, Alexander G, Chakraborty B, Nair V, Konkel J, Greene S, Couper M, Carlier C, Wiese C, Little R, Pomerleau C, Pomerleau O. The role of engagement in a tailored web-based smoking cessation program: randomized controlled trial. J Med Internet Res. 2008 Nov 4;10(5):e36. doi: 10.2196/jmir.1002.

  PMID: 18984557 BACKGROUND

• Ireland ME, Slatcher RB, Eastwick PW, Scissors LE, Finkel EJ, Pennebaker JW. Language style matching predicts relationship initiation and stability. Psychol Sci. 2011 Jan;22(1):39-44. doi: 10.1177/0956797610392928. Epub 2010 Dec 13.

  PMID: 21149854 BACKGROUND

• Fila SA, Smith C. Applying the Theory of Planned Behavior to healthy eating behaviors in urban Native American youth. Int J Behav Nutr Phys Act. 2006 May 30;3:11. doi: 10.1186/1479-5868-3-11.

  PMID: 16734903 BACKGROUND

• Kruikemeier S, Sezgin M, Boerman SC. Political Microtargeting: Relationship Between Personalized Advertising on Facebook and Voters' Responses. Cyberpsychol Behav Soc Netw. 2016 Jun;19(6):367-72. doi: 10.1089/cyber.2015.0652.

  PMID: 27327063 BACKGROUND

• Beltramini, R. F. (1988). Perceived Believability of Warning Label Information Presented in Cigarette Advertising. Journal of Advertising, 17(2), 26-32. https://doi.org/10.1080/00913367.1988.10673110

  BACKGROUND

Related Links

• Link to the chat game for data donation. For this link to work, four individuals need to visit the website using unique URLs (e.g., by changing the URL extension to test1, test2, test3, test4).

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Model Details: The primary intervention study model is parallel, consisting of no messages, non-tailored messages, and linguistically tailored messages. Additionally, we included a crossover arm, where participants will receive tailored messages followed by non-tailored messages, and vice versa.

Study Record Dates

• First Submitted: December 16, 2024
• First Posted: December 19, 2024
• Study Start: October 4, 2024
• Primary Completion: June 1, 2025
• Study Completion: October 1, 2025
• Last Updated: August 12, 2025

Record last verified: 2024-12

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, ANALYTIC CODE
• Time Frame: Beginning after publication of results with no end date

Locations

IE (1); GB (1)