Plant-based diet and risk of all-cause mortality: a systematic review and meta-analysis

Objective: A systematic analysis was conducted to determine the relationship between a plant-based diet and all-cause mortality.

Methods: The PubMed, Embase and Web of Science databases were searched. Two authors selected English documents from the database. Then the other two authors extracted the data and evaluated the Newcastle-Ottawa Scale (NOS). This study adhered to the guidelines of the Preferred Reporting Project (PRISMA) and the PROSPERO Registry protocols. A mixed-effects model combined maximum adjusted estimates, with heterogeneity measured using the I² statistic. The sensitivity analysis validated the analysis's robustness, while publication bias was assessed.

Results: The results of the meta-analysis of 14 articles revealed that a plant-based diet (PDI) can reduce cancer mortality (RR = 0.88, [95% CI 0.79-0.98], τ²: 0.02, I²: 84.71%), cardiovascular disease (CVD) mortality (RR = 0.81, [95% CI 0.76-0.86], τ²: 0.00, I²: 49.25%) and mortality (RR = 0.84, [95% CI 0.79-0.89], τ²: 0.01, I²: 81.99%) risk. Adherence to a healthy plant-based diet (hPDI) was negatively correlated with cancer mortality (RR = 0.91, [95% CI 0.83-0.99], τ²:0.01, I²:85.61%), CVD mortality (RR = 0.85, [95% CI 0.77-0.94], τ²: 0.02, I²: 85.13%) and mortality (RR = 0.85, [95% CI 0.80-0.90], τ²: 0.01, I²: 89.83%). An unhealthy plant-based diet (uPDI) was positively correlated with CVD mortality (RR = 1.19, [95% CI 1.07-1.32], τ²: 0.02, I²: 80.03%) and mortality (RR = 1.18, [95% CI 1.09-1.27], τ²: 0.01, I²: 89.97%) and had a certain correlation with cancer mortality (RR = 1.10, [95% CI 0.97-1.26], τ²: 0.03, I²: 93.11%). Sensitivity analysis showed no contradictory results.

Conclusion: The hPDI was negatively associated with all-cause mortality, and the uPDI was positively associated with all-cause mortality.

Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/#loginpage.