Participants (P) | Intervention (I) | Comparison (C) | Outcomes (O) |
---|---|---|---|
Inclusion criteria | |||
Participants with MetS diagnosed by NCEP-ATP III (1), or IDF (2) criteria, aged ≥ 18 years, and with inadequate vitamin D status | Vitamin D supplementation in the form of vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol) at any dose, given orally, daily, weekly, or monthly | RCTs with intervention compared to placebo | Fasting glucose levels (mg/dL), triglyceride levels (mg/dL), waist circumference (cm), mean blood pressure (mmHg), and HDL- C (mg/dL) (two or more outcomes will be considered in subgroup analyses) |
Exclusion criteria | |||
Participants with MetS aged under 18 years | Vitamin D supplements with other vitamin and chemical element supplements; vitamin D supplementation in fortified foods as the amount of vitamin cannot be defined accurately; studies that used active vitamin D supplementation (1.25-dihydroxy vitamin D) |