Vitamin A supplementation probably leads to lower bitot's spots incidence compared with placebo or usual care (moderate certainty).
Vitamin A supplementation probably leads to lower night blindness incidence compared with placebo or usual care (moderate certainty).
Vitamin D supplementation probably leads to lower pre‐eclampsia compared with placebo or no intervention (moderate certainty).
Vitamin D supplementation probably leads to lower gestational diabetes compared with placebo or no intervention (moderate certainty).
Vitamin D supplementation may leads to lower maternal adverse events: severe postpartum haemorrhage compared with placebo or no intervention (low certainty).
It is very uncertain whether vitamin D supplementation changes maternal adverse event: nephritic syndrome compared with placebo or no intervention (very low certainty).
Vitamin D supplementation showed no clear difference in preterm birth (less than 37 weeks' gestation) compared with placebo or no intervention (low certainty).
Vitamin D supplementation probably leads to lower low birthweight (less than 2500 g) compared with placebo or no intervention (moderate certainty).
Vitamin C supplementation showed no clear difference in major cardiovascular event Physicians compared with placebo (low certainty).
It is very uncertain whether vitamin C supplementation changes cardiovascular mortality Physicians compared with placebo (very low certainty).
It is very uncertain whether vitamin C supplementation changes all‐cause mortality Physicians compared with placebo (very low certainty).
Vitamin C supplementation showed no clear difference in total myocardial infarction (fatal and non‐fatal) Physicians compared with placebo (low certainty).
Vitamin C supplementation showed no clear difference in total stroke (fatal and non‐fatal) Physicians compared with placebo (low certainty).
Vitamin C supplementation showed no clear difference in self‐reported CABG/PTCA Participant self‐reports compared with placebo (low certainty).
Vitamin C supplementation showed no clear difference in self‐reported angina Participant self‐reports compared with placebo (low certainty).
Meta-analysis of randomised trials of vitamin D supplementation for Fasting glucose (Diabetes patients with normal glucose tolerance): WMD 0.01 (95% CI -0.21 to 0.23), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.
Meta-analysis of randomised trials of vitamin D supplementation for Bone mineral density in femoral neck, Community-dwelling adults: WMD 1.10 (95% CI 0.40 to 1.90), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.
Meta-analysis of randomised trials of vitamin D supplementation for Bone mineral density in lumbar spine, Community-dwelling adults: WMD 0.10 (95% CI -0.60 to 0.70), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.
Meta-analysis of randomised trials of vitamin D supplementation for Fractures: non-vertebral, People aged >65 years: RR 0.79 (95% CI 0.63 to 0.99), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.