Here, we conducted a systematic review and meta-analysis to compare the levels of GSH-related metabolites (GSH and GSH disulfide [GSSG]) and the activities of GSH-related enzymes (Glutathione-peroxidase [GPx], GSH reductase [GR], glutamate-cysteine ligase [GCL], GSH synthetase [GS], and GSH S-transferase [GST]) between patients with depression and healthy controls (HC). Here, GSS is linked to major depressive disorder.