Efficacy of Vitamin C Supplementation on Chronic Obstructive Pulmonary Disease (COPD): A Systematic Review and Meta-Analysis

Ting Lei,1,2,* Tingting Lu,3,4,* Haichuan Yu,1,2,* Xiaojie Su,1,2 Chuchu Zhang,1,2 Lei Zhu,1,2 Kehu Yang,4,5 Jian Liu1,2 1Department of Clinical Medicine, The First Clinical Medical College of Lanzhou University, Lanzhou, 730000, People’s Republic of China; 2Department of Critical Care Medicine, the First Hospital of Lanzhou University, Lanzhou, 730000, People’s Republic of China; 3Institute of Clinical Research and Evidence Based Medicine, Gansu Provincial Hospital, Lanzhou, 730000, People’s Republic of China; 4Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, People’s Republic of China; 5Key Laboratory of Evidence-Based Medicine and Knowledge Translation of Gansu Province, Lanzhou, 730000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jian Liu, No. 1, Donggang West Road, Chengguan District, Lanzhou, Gansu Province, Tel +86 136 0935 4197, Email medecinliu@sina.com; Kehu Yang, Evidence-Based Medicine Center, Lanzhou University, 199 West Donggang R.D, Lanzhou, 730000, People’s Republic of China, Email kehuyangebm2020@163.comBackground: In recent years, the pleiotropic roles of antioxidants have drawn extensive attention in various diseases. Vitamin C is a well-known antioxidant, and it has been used to treat patients with chronic obstructive pulmonary disease (COPD). This systematic review and meta-analysis aim to demonstrate the impact of vitamin C supplementation in patients with COPD.Methods: We searched PubMed, Embase, Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure (CNKI), SinoMed, Wanfang, and China Science and Technology Journal Database (cqvip.com) for eligible randomized controlled trials (RCTs) from their respective inception to May 18th, 2021, by using the searching terms of COPD, vitamin C, and RCTs. A meta-analysis was performed to evaluate the effects of vitamin C on lung function, antiox