Fig. 4

Network plots of the included nutritional supplements and their connections based on the efficacy outcomes. The size of the nodes corresponds to the number of studies involving that particular intervention. The thickness of the edges represents the number of studies comparing the two interventions. Panels (a–f): Each panel represents a specific outcome or analysis based on the included studies: a. Forced Expiratory Volume in One Second (FEV1) (% of predicted). b. The ratio of Forced Expiratory Volume in One Second to Forced Vital Capacity (FEV1/FVC). c. 6-minute walk distance (6MWD); d. modified Medical Research Council (mMRC) Dyspnea Scale. e. COPD Assessment Test (CAT). f. St. George’s Respiratory Questionnaire (SGRQ). EAA = Essential amino acid, EPA = Eicosapentaenoic acid, MLT = Melatonin, VD = Vitamin D, VC = Vitamin C, VE = Vitamin E, OPC = Oligomeric proanthocyanidin, AKL1 = a patented botanical formulation containing extracts of Picrorhiza kurroa, Ginkgo biloba, and Zingiber officinale