Late-Life Dietary Patterns and Subsequent Survival Among Adults Aged 90 Years or Older in the Sardinian Blue Zone

Background: Dietary habits in long-lived populations are often interpreted as determinants of exceptional longevity, although most evidence is based on ecological or cross-sectional studies. In this study we examined whether diet measured after extreme old age was reached was associated with subsequent survival among Sardinian Blue Zone residents aged 90 years or older. Methods: The cohort included 200 participants aged 90–106 years who completed a qualitative food-frequency questionnaire covering 17 foods or food groups and were followed for up to seven years. A posteriori dietary patterns were derived using principal component analysis with Varimax rotation. Associations with all-cause mortality were assessed through Kaplan–Meier analysis and Cox models adjusted for age, sex, and comorbidity. Results: Four patterns were identified: dairy–traditional fat, red-meat, chicken–carbohydrate, and plant–starchy food. Greater conformity to the dairy–traditional-fat pattern was associated with lower mortality (HR per 1-SD increase, 0.839; 95% CI, 0.727–0.969, p = 0.017), although this pattern-level association did not meet the 5% false-discovery-rate (FDR) threshold (q = 0.066). The highest versus lowest tertile showed a similar association (HR, 0.682; 95% CI, 0.480–0.969). No other pattern was significantly associated with mortality. In secondary food-specific analyses, higher frequencies of milk, cheese, and chicken consumption were inversely associated with mortality, whereas wine consumption was positively associated with mortality; these four associations remained significant after FDR correction across the 17 foods examined. Conclusions: In adults aged 90 years or older, greater conformity to a dairy-based late-life dietary pattern was associated with longer subsequent survival, although the pattern-level association did not remain significant after FDR correction. These findings concern diet in extreme old age and should not be extrapolated to lifelong dietary factors influencing exceptional longevity.