Fig. 6

Funnel plots of the outcomes: (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