Association Between Dietary Diversity and Intrinsic Capacity Among Chinese Older Adults: A Cross-Sectional Study Based on the CLHLS 2018

Background: Dietary diversity has been suggested to play an important role in healthy ageing, yet its association with intrinsic capacity (IC) remains insufficiently explored. This study aimed to examine the association between dietary diversity and intrinsic capacity among older adults. Methods: This cross-sectional study included 15,166 participants aged ≥65 years from the 2018 Chinese Longitudinal Healthy Longevity Survey. Dietary diversity score (DDS) was constructed from the reported consumption frequencies of 11 food groups and analyzed both continuously and in quartile groups. IC was constructed as a latent variable using confirmatory factor analysis across five domains: cognition, locomotion, psychological function, sensory function, and vitality. Low IC was defined as a factor score below the sample median. Multivariable regression and restricted cubic spline models assessed associations, supplemented by domain-specific, subgroup, and sensitivity analyses. Results: Among 15,166 Chinese adults aged 65 years and older, higher dietary diversity was consistently associated with better intrinsic capacity. In the fully adjusted model, each one-point increase in DDS was associated with a higher IC factor score (β = 0.034, 95% CI = 0.029–0.039). Compared with the lowest DDS quartile, the highest quartile had lower odds of low IC (OR = 0.566; 95% CI: 0.493–0.650; p for trend < 0.001). Spline analysis supported an inverse association without statistically significant evidence of nonlinearity (p = 0.166). Higher DDS was also associated with favorable values across the five domain indicators. Findings persisted after separately excluding the psychological or vitality indicator and using alternative IC thresholds, BMI definitions, and dietary scoring. Conclusions: Higher dietary diversity was associated with better IC and lower odds of sample-defined low IC among Chinese older adults. Prospective and intervention studies are needed to clarify the direction of the association and determine whether increasing dietary diversity helps preserve IC.