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.