Findings

What do systematic reviews say?

14 questions · 15 findings · 5 reviews

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No studies found 0 · 0%GRADE not reported 4 · 26.7%Very low 3 · 20%Low 3 · 20%Moderate 1 · 6.7%High 4 · 26.7%

Vitamin A vs placebo or usual care

All‐cause mortality · children aged between 6 months and 5 years

Vitamin A supplementation leads to lower all‐cause mortality compared with placebo or usual care (high certainty).

1 finding from 1 review

Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age 2022 · Cochrane Headline outcomes only
RR 0.88 [0.83, 0.93]
19 studies · 1202382 participants
High

Vitamin A vs placebo or usual care

Mortality due to LRTI · children aged between 6 months and 5 years

Vitamin A supplementation showed no clear difference in mortality due to LRTI compared with placebo or usual care (low certainty).

1 finding from 1 review

Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age 2022 · Cochrane Headline outcomes only
RR 0.98 [0.86, 1.12]
9 studies · 1098538 participants
Low

Vitamin D vs placebo or control

Mortality (all cause) · Adults (general population)

Meta-analysis of randomised trials of vitamin D supplementation for Mortality (all cause) (Vitamin D2, general population): RR 1.04 (95% CI 0.97 to 1.11), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

2 findings from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
Vitamin D2, general population
RR 1.04 [0.97, 1.11]
8 studies · 17079 participants
GRADE not reported
Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
Vitamin D3, general population
RR 0.91 [0.82, 1.02]
9 studies · 12824 participants
GRADE not reported

Vitamin A vs placebo or usual care

Mortality due to measles · children aged between 6 months and 5 years

Vitamin A supplementation showed no clear difference in mortality due to measles compared with placebo or usual care (low certainty).

1 finding from 1 review

Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age 2022 · Cochrane Headline outcomes only
RR 0.88 [0.69, 1.11]
6 studies · 1088261 participants
Low

Vitamin A vs placebo or usual care

Mortality due to diarrhoea · children aged between 6 months and 5 years

Vitamin A supplementation leads to lower mortality due to diarrhoea compared with placebo or usual care (high certainty).

1 finding from 1 review

Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age 2022 · Cochrane Headline outcomes only
RR 0.88 [0.79, 0.98]
9 studies · 1098538 participants
High

Vitamin D compounds (supplementation) vs placebo or control

All‐cause mortality · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Mortality: RR 1.40 (95% CI 0.38 to 5.15), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.40 [0.38, 5.15]
4 studies · 381 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

All‐cause mortality · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Mortality: RR 1.34 (95% CI 0.34 to 5.24), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.34 [0.34, 5.24]
5 studies · 477 participants
GRADE not reported

Vitamin C vs placebo

All‐cause mortality Physicians · middle‐aged US male physicians

It is very uncertain whether vitamin C supplementation changes all‐cause mortality Physicians compared with placebo (very low certainty).

1 finding from 1 review

Vitamin C supplementation for the primary prevention of cardiovascular disease 2017 · Cochrane Headline outcomes only
HR 1.07 [0.97, 1.18]
1 study · 14641 participants
Very low

Vitamin C vs placebo

Cardiovascular mortality Physicians · middle‐aged US male physicians

It is very uncertain whether vitamin C supplementation changes cardiovascular mortality Physicians compared with placebo (very low certainty).

1 finding from 1 review

Vitamin C supplementation for the primary prevention of cardiovascular disease 2017 · Cochrane Headline outcomes only
HR 1.02 [0.85, 1.22]
1 study · 14641 participants
Very low

Vitamin A supplementation (200,000 to 400,000 IU) vs placebo or no treatment

Change in Infant Mortality Rate per 1000 live births1 · women in the postpartum period

Vitamin A supplementation (200,000 to 400,000 IU) showed no clear difference in infant mortality compared with placebo or no treatment (low certainty).

1 finding from 1 review

Vitamin A supplementation for postpartum women 2016 · Cochrane Headline outcomes only
RR 1.08 [0.77, 1.52]
5 studies · 6090 participants
Low

Neonatal vitamin A supplementation vs control

Neonatal mortality · mortality and morbidity in term neonates

Neonatal vitamin A supplementation showed no clear difference in all‐cause neonatal mortality: risk ratios based on cumulative risk… compared with control (high certainty).

1 finding from 1 review

Neonatal vitamin A supplementation for the prevention of mortality and morbidity in term neonates in low and middle… 2017 · Cochrane Headline outcomes only
RR 0.99 [0.9, 1.08]
5 studies · 126242 participants
High

Neonatal vitamin A supplementation vs control

Infant Mortality at 6 Months · mortality and morbidity in term neonates

Neonatal vitamin A supplementation showed no clear difference in all‐cause infant mortality at 6 months: risk ratios based on… compared with control (high certainty).

1 finding from 1 review

Neonatal vitamin A supplementation for the prevention of mortality and morbidity in term neonates in low and middle… 2017 · Cochrane Headline outcomes only
RR 0.98 [0.89, 1.07]
11 studies · 154634 participants
High

Neonatal vitamin A supplementation vs control

All‐cause infant mortality at 6 months: risk ratios based on cumulative risk (%, adjusted for clustering) ‐ term infants · mortality and morbidity in term neonates

It is very uncertain whether neonatal vitamin A supplementation changes all‐cause infant mortality at 6 months: risk ratios based on… compared with control (very low certainty).

1 finding from 1 review

Neonatal vitamin A supplementation for the prevention of mortality and morbidity in term neonates in low and middle… 2017 · Cochrane Headline outcomes only
RR 0.8 [0.54, 1.18]
3 studies · 22721 participants
Very low

Vitamin A supplementation (200,000 to 400,000 IU) vs placebo or no treatment

Maternal death · women in the postpartum period

Vitamin A supplementation (200,000 to 400,000 IU) showed no clear difference in maternal mortality compared with placebo or no treatment (moderate certainty).

1 finding from 1 review

Vitamin A supplementation for postpartum women 2016 · Cochrane Headline outcomes only
HR 1.01 [0.44, 2.21]
1 study · 8577 participants
Moderate