Adherence to the Mediterranean diet and risk of frailty and pre-frailty in elderly adults: A systematic review and dose-response meta-analysis with GRADE assessment

Several studies have explored the association between Mediterranean diet and frailty, but reported inconsistent results. This systematic review and dose-response meta-analysis summarized the existing evidence on the relationship between Mediterranean diet and risk of frailty and pre-frailty in elderly adults.A systematic search on MEDLINE (PubMed), Scopus, Institute for Scientific Information (ISI) Web of Science and Google Scholar was conducted up to January 2023. Study selection and data extraction were performed by two reviewers working in parallel. Epidemiologic studies reporting relative risks (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) for frailty/pre-frailty in relation to Mediterranean diet (as a priori dietary pattern) were considered. The overall effect size was determined using a random effects model. The body of evidence was assessed by the GRADE approach.A total of 19 studies (12 cohorts and 7 cross-sectionals) were included. In cohort studies (89,608 participants/ 12,866 cases), the highest versus lowest category of Mediterranean diet was inversely associated with frailty (RR: 0.66; 95%CI: 0.55, 0.78; I2:52.4%, PQ-test=0.02). This association was also significant in cross-sectional studies with 1093 cases among 13,581 participants (OR: 0.44; 95%CI: 0.28, 0.70; I2:81.8%, PQ-test<0.001). Moreover, each 2-point increase in Mediterranean diet score was related to decreased risk of frailty in cohort (RR: 0.86; 95%CI: 0.80, 0.93) and cross-sectional (OR: 0.79; 95%CI: 0.65, 0.95) studies. Nonlinear association showed a decreasing slope in curve, sharper at high scores for cohort studies and a steadily reduction for cross-sectional studies. The certainty of the evidence was graded as high in both cohort and cross-sectional studies. Combining 4 effect sizes of 4 studies (12,745 participants/ 4363 cases), the highest adherence to Mediterranean diet was linked to a lower risk of pre-frailty, as well (pooled OR: 0.73; 95%CI: 0.61, 0.86; I2:40.9%, PQ-test=0.17).Adherence to Mediterranean diet is inversely associated with risk of frailty and pre-frailty in older adults and thus, has a considerable impact on health of this population.