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

Background

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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

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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.