Association between phosphorus intake and wrist fracture: the mediating role of bone mineral density

Background: Phosphorus correlates with bone mineral density (BMD), a key factor in fracture risk. Thus, BMD may mediate phosphorus–fractures association, which has not yet been elucidated. Objective: This study aimed to trace phosphorus intake–wrist fracture association, and analyze the mediating role of BMD. Methods: Data were derived from the National Health and Nutrition Examination Survey (NHANES) database. Logistic regression and restricted cubic spline (RCS) analyses were utilized to assess phosphorus intake–wrist fracture association. Subgroup analyses examined differences across populations with varying characteristics. Mediation analysis explored the potential mediating role of BMD in the phosphorus–wrist fracture association. Results: A total of 7,952 participants were included. In the fully adjusted model, compared with the Q1 group, the Q4 group had a remarkably reduced wrist fracture risk (odds ratio [OR] = 0.58, 95% confidence interval [CI]: 0.38–0.88, P = 0.011). RCS revealed a non-linear association between phosphorus intake and wrist fracture (P-non-linear = 0.026). When phosphorus intake was <1,086.5 mg/day, higher intake correlated with lower wrist fracture risk; no significant negative association was observed beyond the threshold. In addition, no subgroups with interactions were identified (P-interaction > 0.05). Mediation analysis indicated that BMD mediated 12.1% of the association between phosphorus intake and wrist fracture. Conclusion: When phosphorus intake is <1,086.5 mg/day, higher intake is associated with reduced wrist fracture risk, with BMD as a key mediator. These findings provided crucial scientific evidence for developing targeted nutritional strategies to prevent wrist fractures.