Plant-based diets and risk of disease mortality: a systematic review and meta-analysis of cohort studies

We aimed to examine the association between adherence to plant-based diets (PBDs) and the risk of mortality among the general population. Relevant investigations were identified through PubMed, Scopus, Embase, and ISI Web of Knowledge. Data were pooled using a random-effects or a fixed-effects model. Twelve prospective cohort studies with 42,697 deaths among 508,861 participants were included. The hazard ratios (HRs) for the highest compared to the lowest category of adherence to the PBDs were 0.90 (95% confidence interval [CI]: 0.82, 0.99; I-2 = 91%, n = 12) for all-cause and 0.77 (95% CI: 0.70, 0.86; I-2 = 36%, n = 8) for coronary heart disease (CHD) mortality. Among PBDs subtypes, there was an inverse association between healthy plant-based 0.92 (95% CI: 0.88, 0.96; I-2 = 0%, n = 2), Pesco-vegetarian 0.81 (95% CI: 0.70, 0.92; I-2 = 0%, n = 2), and Pro-vegetarian 0.74 (95% CI: 0.55, 0.88; I-2 = 61.2%, n = 2) diets and the risk of all-cause mortality. A vegetarian diet was also associated with lower risk of mortality due to cardiovascular 0.92 (95% CI: 0.85, 0.99; I-2 = 0%, n = 5) and CHD 0.76 (95% CI: 0.68, 0.85; I-2 = 35%, n = 7). Our findings show the potential protective role of PBDs against chronic disease mortality. As there were certain limitations in some of the studies included in this systematic review and meta-analysis, further research is necessary to confirm our findings.