Associations of metals and micronutrients with functional disability in Chinese older adults: a mixture analysis approach.

Global aging underscores the public health challenge of disability in activities of daily living (ADL). Nutrition is a modifiable factor for maintaining physical function, yet evidence regarding the joint effects of metals and micronutrients on ADL disability is limited. To evaluate individual and combined associations of seven metals and two micronutrients with ADL disability a Chinese elderly population. This cross-sectional study enrolled 3974 adults aged ≥ 60 years. Blood concentrations of zinc (Zn), cobalt (Co), strontium (Sr), selenium (Se), molybdenum (Mo), manganese (Mn), vanadium (V), folate and vitamin D (VitD) were measured. ADL disability was assessed using the Barthel Index. We utilized logistic regression with restricted cubic splines (RCS) for single-exposure analyses, and weighted quantile sum (WQS) regression, quantile g-computation (QGC), and Bayesian kernel machine regression (BKMR) for mixture analyses. Inverse associations were observed between higher levels of folate (OR = 0.73; 95% CI: 0.63-0.85) and VitD (OR = 0.80; 95% CI: 0.68-0.93) with the risk of ADL disability, with linear dose-response relationships. After covariate adjustment, Mn exhibited a marginal protective effect (OR = 0.91, 95% CI: 0.82-1.00). Co and Sr exhibited U-shaped associations. Mixture analyses consistently indicated an overall protective effect, primarily driven by folate and VitD. Combined exposure to metals and micronutrients is associated with reduced ADL disability risk, with folate and VitD being the most influential components. These findings support holistic nutritional strategies for promoting functional health in aging populations.