Vitamin A supplementation showed no clear difference in mortality due to measles compared with placebo or usual care (low certainty).
Vitamin A supplementation showed no clear difference in mortality due to LRTI compared with placebo or usual care (low certainty).
Vitamin A supplementation may leads to lower diarrhoea incidence Mean episodes per child per year compared with placebo or usual care (low certainty).
Vitamin A supplementation probably leads to lower measles incidence Mean episodes of measles per child per year compared with placebo or usual care (moderate certainty).
Vitamin A supplementation showed no clear difference in LRTI incidence Mean episodes per child per year compared with placebo or usual care (low certainty).
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 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).
It is very uncertain whether summary of findings table ‐ Vitamin B12 supplementation changes maternal anaemia compared with placebo/no vitamin B12 supplementation (very low certainty).
Summary of findings table ‐ Vitamin B12 supplementation showed no clear difference in low birthweight (< 2500 g) compared with placebo/no vitamin B12 supplementation (low certainty).
Summary of findings table ‐ Vitamin B12 supplementation showed no clear difference in preterm birth (< 37 weeks) compared with placebo/no vitamin B12 supplementation (low certainty).
The review found no eligible studies for this question.