Sex-specific mediating role of serum uric acid in the association between dietary diversity and muscle strength in urban community-dwelling older adults.

OBJECTIVES: Dietary diversity is recognized as a key strategy for healthy aging, but the underlying mechanisms linking it to muscle strength, particularly those involving systemic metabolism, remain unclear. This study aimed to examine the association between dietary diversity and muscle strength and explore the potential mediating role of metabolic indicators. METHODS: This cross-sectional study included 1,613 older adults (≥60 years) from the Anhui Urban Aging Cohort. Dietary diversity was assessed using a validated food frequency questionnaire to derive the dietary diversity score (DDS). Metabolic indicators-including serum uric acid (UA), the triglyceride-glucose (TyG) index, total cholesterol (TC), mean arterial pressure (MAP), and metabolic score (MS)-were measured from fasting blood samples. Muscle strength was evaluated by absolute handgrip strength (HGS), BMI-adjusted relative HGS, and low handgrip strength (LGS) defined by the Asian Working Group for Sarcopenia (AWGS) 2019 criteria. Multiple linear and logistic regression models were used to examine the associations, while restricted cubic splines characterized nonlinear relationships. Mediation analysis was performed to assess the potential mediating effect of metabolic indicators. RESULTS: Higher DDS was significantly associated with increased absolute HGS (β = 0.366), increased relative HGS (β = 0.017), and a reduced risk of LGS (OR = 0.875). Notably, DDS was inversely associated with UA levels (β = -2.946). Elevated UA levels were negatively associated with relative HGS (β = -0.0003) and positively associated with the risk of LGS (OR = 1.002). Restricted cubic spline analysis revealed a significant adverse effect of elevated UA (>363 μmol/L) on relative HGS and LGS risk in males. Mediation analysis confirmed that UA significantly mediated the association between DDS and muscle strength, accounting for 5.64% (relative HGS) and 3.79% (LGS) of the total effect in the overall population. This mediating effect was significant only in males (proportions mediated: 9.22% and 8.67%, respectively). CONCLUSION: In urban community-dwelling older adults, dietary diversity benefited muscle strength and was partly mediated by serum uric acid. Notably, this mediating pathway was observed in men, whereas the null findings in women may reflect a complex association pattern. These findings underscore the necessity of considering sex-specific metabolic mechanisms in nutritional strategies against sarcopenia.