**Figure 2.** **Correlation coefficient-based network analysis results.** Network visualization of the correlation-based relationships among profiled aqueous metabolites was performed for young (**A**, *n* = 7), old (**B**, *n* = 8) and mixed (**C**, *n* = 15) groups. Oxidized glutathione and glutathione are highlighted in yellow for (**A)** and (**B**). The width and height of the nodes were scaled using the stress centrality measurements for (**C**).