Adherence to the Mediterranean diet and frailty and disability in older people: A systematic review and meta-analysis featured in the Italian National Guidelines “La Dieta Mediterranea”

Background: The Mediterranean Diet (MD) is a dietary pattern associated with reduced chronic disease risk and increased longevity. This systematic review and meta-analysis aimed to evaluate the association between adherence to the MD and frailty and disability among older people. Methods: A comprehensive literature search was conducted in PubMed/MEDLINE, Cochrane Library, Embase, and Scopus (search date: February 28, 2024) without date restrictions. Observational and interventional studies examining the association between MD adherence (measured by any validated score) and frailty or disability, using any definition, and their complications were included. Study selection and data extraction were performed independently by pairs of reviewers using Covidence. Risk of bias was assessed using the Newcastle-Ottawa Scale. Random-effects meta-analysis was conducted, estimating pooled relative risks (RRs) per 1-point increment in MD adherence score. Heterogeneity was assessed using the I² statistic, and publication bias was evaluated by funnel plot. Certainty of evidence was graded using the NUTRIGRADE approach. Results: Out of 1361 screened records, 19 observational studies were included. Higher MD adherence was associated with a lower incidence (9 cohort studies, n = 94 072 participants; OR = 0.95, 95% CI: 0.93-0.97; moderate certainty of evidence) and prevalence (6 cross-sectional studies, n = 12 277participants; OR = 0.94, 95% CI: 0.90-0.98; low certainty of evidence) of frailty. The association with disability was present only for prevalence (OR = 0.98; 95% CI: 0.97-0.98). Conclusions: Higher adherence to the MD is associated with a reduced presence of frailty and disability in older adults. These findings support public health strategies promoting the MD as a sustainable dietary model for healthy longevity.