Planetary Health Diet Adherence and Frailty in Older Adults: Evidence from the Seniors-ENRICA Cohorts

BACKGROUND: Frailty is a major determinant of disability and adverse outcomes in older adults. The Planetary Health Diet (PHD), a plant-based dietary pattern promoting environmental sustainability, has been associated with lower mortality and reduced chronic disease risk. We examined the association between adherence to the Planetary Health Diet Index (PHDI) and frailty over time using repeated frailty assessments. METHODS: Data came from two cohorts of community-dwelling older adults: Seniors-ENRICA-1 (2008-2015; ≥60 years; n = 3,289) and Seniors-ENRICA-2 (2015-2023; ≥65 years; n = 3,273). Baseline diet was assessed using a validated diet history, and adherence to the PHD was assessed using the PHDI (0-140), based on 15 food groups. Frailty was defined by the Fried phenotype (≥3 criteria of exhaustion, low physical activity, slow gait, muscle weakness, unintentional weight loss). Generalized estimating equation (GEE) models estimated odds ratios (OR) and 95% confidence intervals (CI) for frailty across PHDI tertiles, adjusting for sociodemographic, lifestyle, and clinical factors. RESULTS: Higher PHDI adherence was consistently associated with lower odds of frailty over time. Comparing highest vs. lowest tertiles, multivariable-adjusted ORs (95% CI) were 0.62 (0.42, 0.92) in Seniors-ENRICA-1, 0.40 (0.24, 0.65) in Seniors-ENRICA-2 and 0.52 (0.38, 0.70) in the pooled analyses. Higher PHDI adherence was primarily associated with lower odds of low physical activity, while vegetables and fruits showed the strongest independent associations among individual PHDI components. CONCLUSIONS: Greater PHDI adherence is associated with lower odds of frailty in Spanish older adults, supporting the potential role of sustainable, plant-based dietary patterns for healthy ageing.