SOD1 and metabolic syndrome: 8-OHdG, 8-hydroxy-2'-deoxyguanosine; BMI, body mass index; HDL, high-density lipoprotein; HOMA-IR, homeostasis model assessment of insulin resistance; IL-6: interleukin-6; LDL, low-density lipoprotein; MetS, metabolic syndrome; NA, not available; PAI-1: plasminogen activator inhibitor-1; SOD, superoxide dismutase; TBARS: thiobarbituric acid reactive substances