Strategies and challenges for the recruitment of young healthy participants in the dietary approaches to longevity and health (DiAL health) pilot trial

Abstract

Background

Understanding the impact of nutrition on human aging requires long-term trials in young, healthy, unmedicated adults. As part of the Dietary Approaches for Longevity and Health (DiAL Health) pilot project, we evaluated strategies for recruiting this population for aging-related dietary intervention studies.

Methods

We analyzed recruitment costs to enroll 70 participants (ages 25–49, BMI 22.0–29.9 kg/m²) across two DiAL Health sites and used NHANES data (2017–March 2020) to estimate the proportion of U.S. adults meeting partial trial eligibility. Additionally, a formative study surveyed 492 U.S. adults (≥18 years) to assess interest in aging-focused dietary trials.

Results

Of 2049 applicants screened, 70 were enrolled (3.4 %), with recruitment costs of $1572 per participant at site 1 and $625 at site 2. NHANES data revealed only 3.6 % (555/15,560) of adults met partial eligibility criteria, while 2.2 % (11/492) of formative survey respondents met full eligibility. DiAL Health eligible participants were willing to participate in dietary interventions like time-restricted eating or caloric restriction, but willingness declined for longer or more burdensome trials.

Conclusions

Recruiting young, healthy, unmedicated individuals for aging-focused dietary intervention trials is challenging due to low rates of eligibility and enrollment (∼3–4 % of initial applicants enrolled). Longer trials with stricter eligibility are likely to face greater recruitment barriers, highlighting the need for targeted strategies to engage, recruit, and retain this population effectively.