Live Long, Heart Strong: A Digital Nutrition Intervention for Emerging Adults (LLHS)

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.