Vegetarian diets, dietary trajectories, and mortality risk among older adults: evidence from two nationally representative cohorts.

BACKGROUND AND AIM: Evidence on the long-term mortality implications of vegetarian diets in older adults remains limited. We aimed to examine the associations of vegetarian diets, vegetarian subtypes, and long-term dietary trajectories with all-cause mortality among older adults from two nationally representative cohorts in China and the United States. METHODS AND RESULTS: We analyzed adults aged ≥65 years from the Chinese Longitudinal Healthy Longevity Survey (CLHLS, 2008-2018; n = 6678) and the U.S. National Health and Nutrition Examination Survey (NHANES, 2005-2018; n = 6305). Vegetarian status and subtypes were operationally defined and harmonized across cohorts according to animal-source food intake. Cox proportional hazards models with time-varying covariates were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Dietary trajectories were assessed in CLHLS using repeated dietary assessments. Vegetarian diets were associated with higher all-cause mortality in both cohorts. In CLHLS, vegetarianism was associated with increased mortality risk (HR 1.19, 95% CI: 1.07-1.32), with similar findings in NHANES (HR 1.52, 95% CI: 1.11-2.08). No vegetarian subtype showed a protective association. In CLHLS, consistent vegetarianism and transitions from omnivory to vegetarianism were associated with elevated mortality risk. CONCLUSIONS: Across two culturally distinct populations, operationally defined vegetarian dietary patterns and long-term adherence were associated with higher all-cause mortality among older adults. These findings underscore the importance of nutritional adequacy, overall dietary quality, and age-specific dietary considerations in ageing populations.