Association of the essential metal mixture with biological aging in Chinese older adults: Investigating superoxide dismutase as a potential mediator.

A quartile increase in the essential metal mixture was significantly associated with a 1.77-year decrease in KDM-biological age acceleration.

• 95% CI = -2.43, -1.12 for the association between a quartile increase in EM mixture and KDM-accel
• The study recruited 2787 Chinese older adults in a cross-sectional design
• Biological aging was assessed using KDM-biological age acceleration (KDM-accel), a clinical biomarker-based measure of systemic physiological decline
• Mixture associations were evaluated using weighted quantile sum (WQS), quantile-based g-computation (QGC), and Bayesian kernel machine regression (BKMR) models

Magnesium, rubidium, and manganese were the primary contributors to the negative association between the essential metal mixture and biological age acceleration.

• Mg, Rb, and Mn were identified as primary contributors to the mixture's inverse association with KDM-accel
• Blood concentrations were measured for Mn, Cu, Zn, Se, and Rb; urinary concentrations were measured for Mo, Ca, Mg, and Sr
• Multiple analytical methods including linear regression, GAMs, WQS, QGC, and BKMR were used to evaluate associations
• Bioinformatic analysis revealed a link between these key EMs and oxidative stress

Copper was associated with accelerated biological aging, in contrast to the other primary essential metals studied.

• Cu showed a positive association with KDM-accel, indicating accelerated aging
• This was in contrast to Mg, Rb, and Mn which were associated with decelerated aging
• Blood concentrations of Cu were measured as part of the five blood-based essential metals assessed

Superoxide dismutase (SOD) significantly mediated the association between the essential metal mixture and biological aging.

• The proportion of mediation by SOD was 4.9% for the EM mixture overall
• SOD mediated 7.2% of the association for Rb specifically
• SOD mediated 15.0% of the association for Mn specifically
• Bioinformatic and statistical mediation analyses were used to explore the potential biological process and the role of SOD
• The mediation findings support a role for antioxidant activity in the relationship between essential metals and biological aging

Bioinformatic analysis revealed a link between the key essential metals (Mg, Rb, Mn, Cu) and oxidative stress pathways.

• Bioinformatic analysis was used to explore potential biological processes connecting key EMs to aging
• The analysis supported oxidative stress as a relevant biological mechanism
• Findings were consistent with the statistical mediation results showing SOD as a partial mediator

The study measured essential metals across two biological matrices, with five metals measured in blood and four in urine.

• Blood concentrations were measured for manganese (Mn), copper (Cu), zinc (Zn), selenium (Se), and rubidium (Rb)
• Urinary concentrations were measured for molybdenum (Mo), calcium (Ca), magnesium (Mg), and strontium (Sr)
• A total of 2787 Chinese older adults were recruited in this cross-sectional study