3. Characteristics of included studies (III).
| Study ID | Vitamin | Calcium (mg) | Route | Regimen | Treatment (weeks) | Follow‐up (weeks) | Co‐intervention | |||
| D3 (IU) | D2 (IU) | 25(OH)D (IU) | 1,25(OH)2D (µg) | |||||||
| Abu‐Mouch 2011 | 2000 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 48 | 72 | PEG‐IFN, RBV |
| Atsukawa 2016 | 2000 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 16 | 24 | PEG‐IFN, RBV, SP |
| Barchetta 2016 | 2000 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 24 | 24 | ‐ |
| Behera 2018 | 2000 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 48 | 48 | PEG‐IFN, RBV |
| Boonyagard 2016 | ‐ | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 20 | 20 | |
| Dabbaghmanesh 2018 | 50,000 | ‐ | ‐ | 0.25 | ‐ | Orally | Weekly and daily | 12 | 12 | |
| Esmat 2015 | 2143 | ‐ | ‐ | ‐ | ‐ | Orally | Weekly | 48 | 72 | PEG‐IFN, RBV |
| Foroughi 2016 | 7143 | ‐ | ‐ | ‐ | ‐ | Orally | Weekly | 10 | 10 | ‐ |
| Geier 2018 | 2100 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 48 | 48 | |
| Hosseini 2018 | 600,000 | ‐ | ‐ | ‐ | ‐ | Intramuscularly | Single dose | Single dose | 4 | Vitamin E 400 IU/day |
| Hussain 2019 | 50,000 | ‐ | ‐ | ‐ | ‐ | Orally | Weekly | 12 | 12 | |
| Jeong 2019 | 800 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 24, 48 | 48, 72 | PEG‐IFN, RBV |
| Jha 2017 | 300,000; 800 | ‐ | ‐ | ‐ | 1000 | Intramuscularly and orally | Single dose; daily | 24 | 24 | |
| Komolmit 2017a | ‐ | 60,000; 80,000; 100,000 | ‐ | ‐ | ‐ | Orally | Weekly | 6 | 6 | |
| Komolmit 2017b | ‐ | 60,000; 80,000; 100,000 | ‐ | ‐ | ‐ | Orally | Weekly | 6 | 6 | |
| Lorvand Amiri 2016 | 1000 | ‐ | ‐ | ‐ | 500 | Orally | Daily | 10 | 12 | ‐ |
| Mobarhan 1984 | ‐ | 17,857 | 2400 | ‐ | ‐ | Orally | Daily | 52 | 52 | ‐ |
| Nimer 2012 | 2000 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 24 | 48 | PEG‐IFN, RBV |
| Pilz 2016 | 2800 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 8 | 8 | ‐ |
| Sakpal 2017 | 600,000 | ‐ | ‐ | ‐ | ‐ | Intramuscularly | Single dose | Single dose | 24 | |
| Sharifi 2014 | 3571 | ‐ | ‐ | ‐ | ‐ | Orally | Twice a week | 16 | 16 | ‐ |
| Shiomi 1999a | ‐ | ‐ | ‐ | 1 | ‐ | Orally | Daily | 52 | 52 | ‐ |
| Shiomi 1999b | ‐ | ‐ | ‐ | 1 | ‐ | Orally | Daily | 52 | 52 | ‐ |
| Taghvaei 2018 | 50,000 | ‐ | ‐ | ‐ | ‐ | Orally | Weekly | 12 | 72 | Lifestyle modification |
| Vosoghinia 2016 | 1600 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 12 | 12 | PEG‐IFN, RBV |
| Xing 2013 | ‐ | ‐ | ‐ | 0.25 | 1000 | Orally | Daily | 4 | 4 | ‐ |
| Yokoyama 2014 | 1000 | ‐ | ‐ | ‐ | ‐ | Orally | Daily | 16 | 24 | PEG‐IFN, RBV |
1,25(OH)2D: calcitriol 25(OH)D: calcidiol IU: international unit PEG‐IFN: pegylated‐interferon RBV: ribavirin SP: simeprevir