Plant-based diet and mortality in adults with cardiovascular-kidney-metabolic syndrome: evidence from NHANES with mediation by leukocyte telomere length

Higher intake of healthy plant-based foods is associated with a reduced risk of numerous chronic diseases. This study examined the associations between plant-based diet (PBD) quality with all-cause and cardiovascular disease (CVD) mortality in adults with cardiovascular-kidney-metabolic (CKM) syndrome, and evaluated the potential mediating role of leukocyte telomere length (LTL). Adult participants with CKM syndrome from the 1999-2002 National Health and Nutrition Examination Survey were included. PBD quality was assessed using the total plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI). Cox proportional hazards regression analysis was used for mortality associations by reporting hazard ratios (HRs) and 95% confidence intervals (CIs). Among 4875 participants (mean age 50.84 years, 50.20% women) included, 1880 (617 CVD-related) deaths occurred during a median follow-up time of 213 months. In multivariable-adjusted models, participants in the highest vs lowest quartile of hPDI had a 59.8% lower risk of all-cause mortality (HR = 0.402, 95% CI 0.345-0.468) and a 60.9% lower risk of CVD mortality (HR = 0.391, 95% CI 0.266-0.575). Conversely, the highest quartile of uPDI was associated with a 75.4% increased risk of all-cause mortality (HR = 1.754, 95% CI 1.489-2.066) and a 59.5% increased risk of CVD mortality (HR = 1.595, 95% CI 1.220-2.085). Mediation analysis indicated that LTL mediated 7.7, 5.8, and 4.3% of the effect of total PDI, hPDI, and uPDI on all-cause mortality, and 1.3, 1.0, and 8.0% of the effect on CVD mortality, respectively. Thus, greater adherence to a healthful PBD is associated with significantly lower all-cause and CVD mortality in adults with CKM syndrome, an association partially mediated by LTL.