In the prospective Lifelines cohort tracking 105,812 Dutch adults over a median 13.25 years, adherence to the MEDLIFE index — a 23-item composite scoring Mediterranean diet quality, physical activity, rest, and social habits — showed a clear dose-response relationship with all-cause mortality. Compared to the lowest adherence quartile, the highest quartile had a 30% lower mortality hazard (HR 0.70; 95% CI 0.64–0.77) after full covariate adjustment. The protective effect was amplified by income: the highest MEDLIFE adherence combined with the highest income yielded a 46% mortality reduction (HR 0.54), versus 33% for the highest adherence-education pairing.
Several features make this study notable. First, the cohort is exceptionally large and the follow-up long enough (3,976 deaths) to produce stable estimates across socioeconomic subgroups. Second, the finding that income modifies the association more powerfully than education challenges the intuition that health literacy is the dominant socioeconomic driver — purchasing power matters independently. Third, and arguably most important for public health: even the most economically disadvantaged participants who achieved high MEDLIFE adherence showed meaningful mortality reductions, suggesting lifestyle change is not purely a privilege of the affluent.
Limitations include the observational design (residual confounding is inevitable), self-reported baseline socioeconomic data, and a predominantly Northern European population — generalisability to Mediterranean or lower-income countries is uncertain. Still, the scale and duration place this among the stronger prospective evidence linking a holistic lifestyle index to longevity across socioeconomic strata.