Live Long, Heart Strong (LLHS) is a theory-guided, digital twin-supported nutrition intervention designed to promote cardiovascular health behaviors among emerging adults (18-25 years). Developed using a human-centered design approach and informed by Social Cognitive Theory, the intervention incorporates personalized nutrition education, interactive learning activities, goal setting, self-monitoring, quizzes, youth-informed educational videos, tailored feedback, reminders, and gamification to support healthy eating behaviors and improve dietary quality. In this pilot randomized controlled trial, participants will be randomly assigned to either the LLHS intervention or an active comparator consisting of a static, non-personalized digital nutrition education toolkit containing similar evidence-based educational content without personalization, interactivity, or behavioral support features. The study will evaluate implementation outcomes (feasibility, usability, acceptability, and appropriateness), changes in psychosocial and behavioral outcomes related to healthy eating, and preliminary cardiovascular-related health indicators. Findings will inform continued refinement of the LLHS intervention and the design of a future fully powered efficacy trial.
Cardiovascular disease (CVD) remains the leading cause of death in the United States, and many modifiable risk factors begin to develop during emerging adulthood. This developmental period represents an important opportunity to establish lifelong dietary habits and other health-promoting behaviors that support long-term cardiovascular health. However, emerging adults often encounter barriers to healthy eating, including limited nutrition knowledge and food preparation skills, financial constraints, time pressures, and increasing independence in food-related decision making. Existing nutrition interventions frequently do not address these developmental and contextual challenges or sustain long-term engagement. The Live Long, Heart Strong (LLHS) intervention was developed to address these gaps through a theory-guided digital nutrition intervention specifically designed for emerging adults. Intervention development follows a human-centered design approach, incorporating iterative input from emerging adults throughout the design and refinement process to improve the relevance, usability, and acceptability of intervention content and features. The intervention is informed by Social Cognitive Theory and incorporates evidence-based behavior change methods designed to strengthen behavioral capability, self-efficacy, outcome expectations, and self-regulation, with the goal of improving dietary behaviors that support long-term cardiovascular health. Participants will be randomly assigned to one of two study arms. The experimental group will receive access to the LLHS digital intervention, which includes personalized nutrition education, interactive learning activities, goal setting, self-monitoring, quizzes, youth-informed educational videos, tailored feedback, reminders, gamification, and digital twin-supported personalized guidance. The active comparator group will receive access to a static, non-personalized digital nutrition education toolkit containing similar evidence-based educational information presented without personalization, tailoring, interactivity, or behavioral support features. The primary objectives of this pilot randomized controlled trial are to evaluate the feasibility, usability, acceptability, and preliminary effectiveness of the LLHS intervention relative to the active comparator. Primary outcomes include implementation outcomes (usability, acceptability, appropriateness, and feasibility). Secondary outcomes include changes in Social Cognitive Theory constructs, nutrition literacy, and dietary quality assessed using the Healthy Eating Index. In addition, participants will complete in-person baseline and post-intervention assessments of skin carotenoid levels using the VeggieMeter and other anthropometric and cardiovascular-related health indicators (e.g., body mass index, waist circumference, and resting blood pressure) to evaluate the feasibility of these measurements and explore preliminary intervention-related changes. Participant demographic and socioeconomic characteristics, including measures such as food security, financial status, living conditions, and other relevant characteristics, will also be collected to characterize the target population and inform interpretation of intervention effects. Findings from this pilot trial will inform continued refinement of the LLHS intervention, establish the feasibility of study procedures and outcome assessments, and provide preliminary evidence to support a future fully powered efficacy trial.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
60
The Live Long, Heart Strong (LLHS) Digital Nutrition Intervention is a theory-guided behavioral intervention developed using a human-centered design approach and informed by Social Cognitive Theory. The intervention is designed to promote healthy eating behaviors for cardiovascular disease prevention among emerging adults through a personalized digital platform. Participants receive tailored nutrition education, interactive learning activities, goal setting, self-monitoring, quizzes, youth-informed educational videos, tailored feedback, reminders, and gamification. Intervention content focuses on developing knowledge, behavioral capability, self-efficacy, observational learning, outcome expectations, and self-regulation to support sustainable dietary behavior change.
The Static Digital Nutrition Education Toolkit is an active comparator consisting of evidence-based digital educational materials related to healthy eating and cardiovascular disease prevention. Participants receive the same general educational topics as the experimental group through a static, non-personalized digital format. The toolkit does not include interactive activities, personalization, tailored feedback, goal setting, self-monitoring, reminders, or gamification.
Intervention Feasibility
Feasibility of the LLHS intervention, assessed by participant retention, intervention completion, and adherence throughout the study.
Time frame: Baseline through end of the intervention (8 weeks)
Intervention Usability
Usability of the LLHS digital intervention will be assessed using the mHealth App Usability Questionnaire (MAUQ). The MAUQ is a 21-item instrument with scores ranging from 1 to 7, where higher scores indicate greater perceived usability of the mobile health application.
Time frame: End of the intervention (8 weeks)
Intervention Acceptability
Acceptability of the LLHS digital intervention will be assessed using the Acceptability of Intervention Measure (AIM). The AIM is a 4-item instrument with scores ranging from 1 to 5, where higher scores indicate greater perceived acceptability of the intervention.
Time frame: End of the intervention (8 weeks)
Self-Efficacy for Healthy Eating
Healthy eating self-efficacy will be assessed using the 7-item Healthy Eating subscale of the Healthy Eating and Weight Self-Efficacy (HEWSE) Scale. Scores range from 1 to 5, with higher scores indicating greater confidence in one's ability to make and maintain healthy eating behaviors.
Time frame: Baseline and end of intervention, approximately 8 weeks
Dietary Quality
Dietary quality will be assessed using the Healthy Eating Index-2020 (HEI-2020) calculated from dietary recall data. HEI-2020 scores range from 0 to 100, with higher scores indicating greater adherence to the Dietary Guidelines for Americans and higher overall dietary quality.
Time frame: Baseline and end of intervention, approximately 8 weeks
Nutrition Literacy
Nutrition literacy will be assessed using the Young Adult Nutrition Literacy Tool (YA-NLT). Total scores range from 0 to 5, with higher scores indicating greater nutrition literacy.
Time frame: Baseline and end of intervention (approximately 8 weeks)
Self-Regulation for Healthy Eating
Self-regulation for healthy eating will be assessed using the Self-Regulation of Eating Behaviour Questionnaire (SREBQ). Total scores range from 1 to 5, with higher scores indicating greater self-regulation of eating behaviors.
Time frame: Baseline and end of intervention (approximately 8 weeks)
Body Mass Index
Body mass index (kg/m²) calculated from measured height and weight collected during in-person study visits.
Time frame: Baseline and end of intervention (~8 weeks)
Waist Circumference
Waist circumference measured using standardized anthropometric procedures to provide a preliminary indicator of central adiposity and cardiometabolic risk.
Time frame: Baseline and end of intervention (~8 weeks)
Resting Blood Pressure
Resting systolic and diastolic blood pressure measured using a validated automated blood pressure monitor.
Time frame: Baseline and end of intervention
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