Adherence to the Mediterranean Diet in Relation to All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective cohort studies rather than randomized trials.
PubMed 31111871 · doi:10.1093/advances/nmz041
What was done
A systematic review and dose-response random-effects meta-analysis of prospective cohort studies indexed in PubMed, Scopus, ISI Web of Knowledge, and Embase up to August 24, 2018. The authors evaluated linear and non-linear associations between adherence to a Mediterranean diet (evaluated per 2-point increment in adherence score) and all-cause mortality risk.
What was found
Twenty-nine prospective studies encompassing 1,676,901 participants and 221,603 all-cause mortality cases were included. A 2-point increment in Mediterranean diet adherence was associated with a lower risk of all-cause mortality (pooled HR: 0.90, 95% CI: 0.89 to 0.91; I2 = 81.1%). The inverse association was stronger in Mediterranean regions (HR: 0.82) than non-Mediterranean regions (HR: 0.92), and in studies utilizing the Panagiotakos score. Dose-response modeling indicated a linear reduction in mortality risk as adherence increased.
Why it matters
This study provides large-scale evidence of a linear, inverse dose-response relationship between Mediterranean diet adherence and all-cause mortality, highlighting potentially greater magnitude of benefit in Mediterranean regions.
Limits
The underlying evidence is derived entirely from observational cohorts, precluding causal inference and leaving open the possibility of residual confounding from unmeasured lifestyle factors. Substantial statistical heterogeneity was observed across studies (I2 = 81.1%), and dietary assessment methods as well as adherence scoring tools varied across included cohorts.
Cited by
- supports A meta-analysis of 29 observational studies covering over 1.6 million people found that greater adherence to a Mediterranean diet was associated with a 10% reduction in all-cause mortality.