Factors Influencing Dietary Supplement Selection Among Older Adults in Iran: A Discrete Choice Experiment

Introduction: Understanding factors that shape dietary supplement choices among older adults is important for guiding healthcare, industry, and policy. This study aimed to identify key factors influencing supplement choices among older adults using a discrete choice experiment (DCE). Methods: This study recruited 384 participants aged ≥ 65 years (mean age 73.7, 52% women) from pharmacies in Tehran and Karaj. Attributes were developed through literature review and expert consultation and analyzed using a DCE with multinomial logit model. Results: Participants had a mean age of 73.67 years; 52% were women. Physician recommendation emerged as the most influential factor, followed by supplement form, monthly cost, ingredient composition, and country of manufacture. Higher costs significantly reduced selection likelihood, vitamin-mineral products were preferred over herbal-only supplements, and foreign-licensed products were favored over domestic ones. Socioeconomic and demographic variables showed no significant effects. Discussion: These findings highlight the dominant role of healthcare provider influence and cost sensitivity, along with perceptions of formulation quality and origin. Results can support professionals, manufacturers, and policymakers in developing supplement strategies tailored to older adults’ needs and expectations. Keywords: dietary supplements, aged, discrete choice experiment, patient preference