Oxidative stress indicators mediated the association of dietary copper intake with low muscle mass: a cross-sectional study

This study aimed to investigate the association between dietary copper intake and muscle mass. Low muscle mass was defined according to the Foundation for the National Institutes of Health (FNIH) consensus. Among 9693 adults (female 50.3%), mean age was 39.5 ± 0.3 years, and mean copper intake was 1.2 ± 0.01 mg/day. Compared to the lowest quintile, participants in the highest quintile of copper intake exhibited a decreased risk of low muscle mass (OR = 0.43; 95% CI: 0.26, 0.72). For per 0.5 mg/day increase in copper intake, the risk of low muscle mass was decreased by 20% (P < 0.05). This association was mediated by serum albumin, bilirubin, and gamma-glutamyl transferase, with mediating proportions of 5.92%, 2.84%, and 2.56% respectively (P < 0.001). In summary, increasing copper intake may serve as a protective factor to prevent muscle loss, and oxidative stress may be crucial to this process.