Association between vegetarian diet and risk of frailty in Chinese older adults: a prospective study

Abstract

Background: Although dietary patterns rich in plant-based food have been linked to lower frailty risk in older adults, the relationship between vegetarian diet and incident frailty has been understudied. Therefore, this study aimed to investigate the association between vegetarian diet and risk of frailty in a nationwide representative cohort of Chinese community-dwelling older adults (≥ 65 years old).

Methods: Included were 27,917 participants (age range: 65-122 years; mean age: 86.9 ± 11.0 years) free of frailty at study entry, from the Chinese Longitudinal Healthy Longevity Survey initiated in 1998. According to the consumption of meat, fish, eggs, and milk products assessed by the food frequency questionnaire at each survey, participants were categorized as omnivores (n = 23,541) or vegetarians (n = 4376), among which were further classified as pesco-vegetarians (n = 1547), ovo-lacto-vegetarians (n = 1745), and vegans (n = 1084). Diet trajectory (from baseline to the first follow-up survey, median interval: 2.8 years) categories included Stick-To-Omnivorous, Stick-To-Vegetarian, Omnivorous-To-Vegetarian, and Vegetarian-To-Omnivorous. Frailty was defined by a frailty index > 0.25 based on 40 variables reflecting health deficits. We used multivariable time-varying Cox proportional hazard models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of frailty risk according to different diet groups and diet trajectories.

Results: During a median follow-up of 3.0 (IQR: 1.83-5.33) years, vegetarians showed a higher risk of incident frailty (HR [95% CI]: 1.13 [1.07, 1.20]) compared to omnivores. Similar patterns were observed across subgroups of vegetarian diet, including pesco-vegetarians (HR [95% CI]: 1.15 [1.05, 1.26]), ovo-lacto-vegetarians (HR [95% CI]: 1.11 [1.02, 1.20]), and vegans (HR [95% CI]: 1.12 [1.01, 1.25]). In terms of diet trajectory, maintaining vegetarian diets (HR [95% CI]: 1.19 [1.03, 1.38]), transition from the omnivorous diet to vegetarian diets (HR [95% CI]: 1.16 [1.04, 1.30]), and transition from vegetarian diets to the omnivorous diet (HR [95% CI]: 1.14 [1.02, 1.27]) were all associated with higher risks of frailty, compared with maintaining an omnivorous diet.

Conclusions: In this prospective study, vegetarian diets were observed to be associated with higher frailty risk, compared to the omnivorous diet in Chinese older adults. Future research is needed to confirm our observations.

Keywords: Chinese Longitudinal Healthy Longevity Survey; Frailty; Older adults; Prospective cohort study; Vegetarian diet.