Effects of a senior-friendly diet on health-related quality of life and quality-adjusted life expectancy among older adults in South Korea: a fixed-effects and difference-in-differences analysis

Introduction: Rapid population aging presents significant nutritional challenges for older adults, as physiological declines often lead to malnutrition and reduced quality of life. While senior-friendly diets have been developed to accommodate these needs, their broader economic and welfare impacts remain under-researched. Methods: To address this gap, a randomized two-period crossover intervention study was conducted with community-dwelling older adults at a welfare center in South Korea. Participants received either a senior-friendly diet or a standard diet for ten weeks before switching conditions after a one-week washout period. Using individual fixed-effects models as the primary analysis and difference-in-differences models as a robustness check, changes in utility weights and quality-adjusted life expectancy were analyzed. Results: The results demonstrated that consuming the senior-friendly diet led to statistically significant improvements in both utility weights and quality-adjusted life expectancy. These overall gains were primarily driven by significant enhancements in physical functioning, specifically in mobility, self-care, usual activities, and the reduction of pain and discomfort. Discussion: These findings suggest that senior-friendly dietary interventions may improve physical health and quality-adjusted life expectancy among older adults in community-based welfare settings, though further research with larger and more diverse samples is needed to assess the generalizability of these effects.