Associations of plant-based diets with all-cause and cause-specific mortality and life expectancy among participants with cardiometabolic disorders from UK, USA, and China

AIMS: It remains largely unknown whether and how plant-based diets are associated with mortality and life expectancy among people with cardiometabolic disorders, who have a significantly increased risk of mortality. We examined associations of plant-based diets with mortality and life expectancy among people with cardiometabolic disorders. METHODS: We followed 78,151 participants with cardiometabolic disorders, including obesity, diabetes, or cardiovascular diseases (CVD) from UK Biobank (UKB) (2006-2022), US National Health and Nutrition Examination Survey (NHANES) (1999-2019) and Chinese Longitudinal Healthy Longevity Survey (CLHLS) (2008-2019). We created an overall plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI). We used Cox models to compute HRs for mortality, and applied life table to estimate life expectancy. RESULTS: During a mean follow-up of 11.4 years, 12,150 deaths occurred in three cohorts. A higher PDI was associated with lower all-cause, CVD, and other mortality among participants with cardiometabolic disorders. The pooled HR and 95%CI for extreme quartiles of PDI was 0.85 (0.81, 0.90) for all-cause mortality, 0.82 (0.72, 0.93) for CVD mortality, and 0.82 (0.69, 0.97) for other mortality. Compared with people in the lowest quartile of hPDI or uPDI, those in the highest quartile of hPDI had 19-29% lower all-cause, CVD, cancer, and other mortality; while people in the highest quartile of uPDI had 28-43% higher all-cause, CVD, cancer, and other mortality. Comparing extreme quartiles, PDI, hPDI, and uPDI were associated with 1.22-year and 2.10-year longer life expectancy, and 2.22-year shorter life expectancy at age 65 years, respectively. These associations remained similar across the three cohorts and among people with obesity, T2D, and CVD, separately. CONCLUSIONS: Among participants with cardiometabolic disorders, overall and healthful plant-based diets were associated with lower all-cause and cause-specific mortality and longer life expectancy, while unhealthful plant-based diet was associated with higher mortality and shorter life expectancy.