Mortality Effects of Healthy versus Unhealthy Plant Based Diets
In this meta-analysis, researchers review epidemiological studies that employed a simple classification system to assess both how healthy a diet is and how vegan it is, the plant-based diet index. It is perfectly possible to eat an unhealthy vegan diet: just consume a lot of sugar and processed grains. The result is much as one might expect, in that those adhering to a more vegan diet exhibit lower mortality provided that the diet is healthy. There is some debate regarding which of the possible mechanisms are important in producing this outcome, such as levels of inflammation, a modestly lower overall calorie and protein intake, and so forth.
The adherence to plant-based diets has been shown to positively impact longevity by reducing the incidence and severity of lifestyle-related diseases. Previous studies on the association of plant-based dietary pattern, as evaluated by plant-based dietary index (PDI), healthy plant-based dietary index (hPDI) and unhealthy plant-based dietary index (uPDI), with mortality risk have reported inconsistent results. We performed the present meta-analysis to summarize evidence on this association and to quantify the potential dose-response relationship based on all available cohort studies.
A total of 11 eligible cohort studies (13 datasets) were eventually included in this meta-analysis. Participants in the highest quintile of both the PDI and hPDI had a significantly decreased risk of all-cause mortality (pooled hazard ratio for PDI = 0.85; pooled hazard ratio for hPDI = 0.86) compared to participants in the lowest quintile. In contrast, the highest uPDI was associated with an increased risk of mortality (pooled hazard ratio for uPDI = 1.20). In conclusion, greater adherence to PDI or hPDI dietary pattern was associated with a lower risk of mortality, whereas uPDI dietary pattern was positively associated with mortality risk.