Abstract: ORIGINAL RESEARCH published: 15 December 2021 doi: 10.3389/fimmu.2021.717816 The Effect of Vitamin C on Pathological Parameters and Survival Duration of Critically Ill Coronavirus Disease 2019 Patients: A Randomized Clinical Trial Nazanin Majidi 1, Faezeh Rabbani 2, Somayeh Gholami 3, Maryam Gholamalizadeh 4, Fatemeh BourBour 5, Samira Rastgoo 5, Azadeh Hajipour 6, Mahdi Shadnoosh 7, Mohammad Esmail Akbari 4, Bojlul Bahar 8, Narjes Ashoori 5, Atiyeh Alizadeh 9, Forough Samipoor 3, Alireza Moslem 10, Saeid Doaei 11* and Katsuhiko Suzuki 12* Edited by: Alberto Finamore, Council for Agricultural and Economics Research (CREA), Italy Reviewed by: Paul Ellis Marik, Eastern Virginia Medical School, United States Raffaella Comitato, Council for Agricultural and Economics Research (CREA), Italy *Correspondence: Saeid Doaei Sdoaee@yahoo.com Katsuhiko Suzuki katsu.suzu@waseda.jp Specialty section: This article was submitted to Nutritional Immunology, a section of the journal Frontiers in Immunology Received: 31 May 2021 Accepted: 24 November 2021 Published: 15 December 2021 Citation: Majidi N, Rabbani F, Gholami S, Gholamalizadeh M, BourBour F, Rastgoo S, Hajipour A, Shadnoosh M, Akbari ME, Bahar B, Ashoori N, Alizadeh A, Samipoor F, Moslem A, Doaei S and Suzuki K (2021) The Effect of Vitamin C on Pathological Parameters and Survival Duration of Critically Ill Coronavirus Disease 2019 Patients: A Randomized Clinical Trial. Front. Immunol. 12:717816. doi: 10.3389/fimmu.2021.717816 1 Department of Nutrition, Science and Research Branch, Islamic Azad University, Tehran, Iran, 2 Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran, 3 Razi Hospital, Guilan University of Medical Sciences, Rasht, Iran, 4 Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran, 5 Department of Clinical Nutrition and Dietetics, Research Institute Shahid Beheshti University of Medical Science, Tehran, Iran, 6 School of Health, Qazvin University of Medical Sciences, Qazvin, Iran, 7 Department of Clinical Nutrition, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran, 8 Nutrition Sciences and Applied Food Safety Studies, Research Centre for Global Development, School of Sport & Health Sciences, University of Central Lancashire, Preston, United Kingdom, 9 Department of Pharmacognosy, Faculty of Pharmacy, Tehran University of Medical Science, Tehran, Iran, 10 Department of Anesthesiology, Sabzevar University of Medical Sciences, Sabzevar, Iran, 11 Reproductive Health Research Center, Department of Obstetrics and Gynecology, School of Medicine, Al-Zahra Hospital, Guilan University of Medical Sciences, Rasht, Iran, 12 Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan Introduction: Vitamin C has been reported to have beneficial effects on patients with coronavirus disease 2019 (COVID-19). This study aimed to investigate the effect of vitamin C supplementation on pathological parameters and survival duration of critically ill patients with COVID-19. Methods: This clinical trial was conducted on 120 hospitalized critically ill patients infected with COVID-19. The intervention group (n = 31) received one capsule of 500 mg of vitamin C daily for 14 days. The control group (n = 69) received the same nutrition except..