Dietary Copper Intake and Biological Aging Among US Adults, <scp>NHANES</scp> 2003–2018

While the health effects of dietary copper intake have been widely studied, no research to date has specifically examined its association with biological aging. Here, we aim to explore the relationship between dietary copper intake and biological aging, while examining the mediating role of dietary inflammatory index (DII). This cross-sectional study included 18,160 adults from the 2003 to 2018 National Health and Nutrition Examination Survey (NHANES). Weighted multivariable linear regression models, subgroup analysis, trend tests, and restricted cubic spline (RCS) were used to analyze the relationship between dietary copper intake and biological aging. Biological aging was measured from different perspectives including phenotypic age (PhenoAge) and phenotypic age acceleration (PhenoAgeAccel). Additionally, mediation analysis explored the mediating role of DII in the above relationships. In this study, we found dietary copper intake was negatively associated with biological aging. Specifically, each 1-unit increase in dietary copper intake was associated with a 1.12-year decrease in PhenoAge and a 1.45-year decrease in PhenoAgeAccel. RCS models revealed a non-linear relationship between dietary copper intake and biological aging (p for nonlinear < 0.001). Specifically, the inverse association was stronger at lower intake levels, with the protective effect plateauing at higher values. Mediation analysis further indicated that DII mediated the above relationships. This study demonstrates a significant negative association between dietary copper intake and biological aging. Public health strategies that increase dietary copper intake may help reduce the burden of biological aging.