Table 1.
Characteristics of the included studies and study populations (n = 601).
| Study | Country | Subjects (n) | Intervention | Supplemented Dose of Vitamin D | Vitamin D Supplements: Formulation and Manufacturer | Time of Intervention | Ethnicity |
|---|---|---|---|---|---|---|---|
| Abootorabi et al. [16], 2017 | Iran | 36 | Cholecalciferol (n = 19) Placebo (n = 17) | 50,000 IU/weekly | Capsules: D-Vitamin 50,000; Zahravi Pharm Co, Tabriz, Iran | 8 weeks | Asian: 100% |
| Ardabili et al. [17], 2012 | Iran | 50 | Cholecalciferol (n = 24) Placebo (n = 26) | 50,000 IU every 20 days Placebo | Capsules: D-Vitin 50,000, Zahravi Pharm Co, Tabriz, Iran | 60 weeks | Asian: 100% |
| Asemi et al. [18], 2014 a | Iran | 78 | Cholecalciferol (n = 26) Cholecalciferol + Calcium(n = 26) placebo (n = 26) |
50,000 IU/week 50,000 IU/week + 1000 mg/d Placebo |
Tablets: Dana Pharmaceutical Company (Tabriz, Iran) and Barij Essence Pharmaceutical Company (Kashan, Iran). | 8 weeks | Asian: 100% |
| Bonakdaran et al. [24], 2012 b | Iran | 31 | Calcitriol (n = 15) Placebo (n = 16) |
200 IU/d Placebo |
Capsules: Zahravi, Tabriz, Iran | 12 weeks | Asian: 100% |
| Gupta et al. [21], 2017 | India | 50 | Cholecalciferol (n = 25) Placebo (n = 25) | 60,000 IU/weekly Placebo | Not given | 12 weeks | Asian: 100% |
| Irani et al. [15], 2015 | USA | 53 | Cholecalciferol (n = 35) Placebo (n = 18) | 50,000 IU/weekly Placebo | Capsules: manufacturer not given | 8 weeks | Vitamin D group: Hispanic: 69.4%; Asian: 25%; Black: 5.5% Placebo group: Hispanic: 72.2%; Asian: 22.2%; Black: 5.5% |
| Jamilian et al. [2], 2017 | Iran | 90 | Cholecalciferol (n = 30) Cholecalciferol (n = 30) Placebo (n = 30) | 1000 IU/d 4000 IU/d Placebo |
Capsules: Zahravi Pharmaceutical Company (Tabriz, Iran) and Barij Essence Pharmaceutical Company Kashan, Iran | 12 weeks | Asian: 100% |
| Jamilian et al. [22], 2017 | Iran | 60 | Cholecalciferol+Magnesium+Zinc+Calcium (n = 30) Placebo (n = 30) | 200 IU + 100 mg + 4 mg + 400 mg/d Placebo |
Tablets: Vitane (Wolfratshausen, Germany) and Barij Essence Pharmaceuticals (Kashan, Iran), | 12 weeks | Asian: 100% |
| Karamali et al. [19], 2018 | Iran | 55 | Cholecalciferol + Calcium + Vitamin K (n = 28) Placebo (n = 27) | 200 IU + 500 mg + 90 μg/d Placebo |
Capsules: Arian SalamtSina (Tehran, Iran) and Barij Essence Pharmaceutical Company(Kashan, Iran) | 8 weeks | Asian: 100% |
| Maktabi et al. [23], 2017 | Iran | 70 | Cholecalciferol (n = 35) Placebo (n = 35) | 50,000 IU every 2 weeks Placebo |
Capsules: Zahravi, Tabriz, Iran | 12 weeks | Asian: 100% |
| Raja-Khan et al. [20], 2014 | USA | 28 | Cholecalciferol (n = 13) Placebo (n = 15) | 12,000 IU/d Placebo |
Gel caps: Maximum D3 (with soy lecithin oil): BTR Group, Inc. (Pittsfield, IL, USA) | 12 weeks | N/A |
N/A: Not available. a In this study, additional supplementation with calcium alone was also tested. These results were not taken into account in this meta-analysis. b In this study, asecond control grouponly took metformin. These results were not taken into account in this meta-analysis.