Findings

What do systematic reviews say?

63 questions · 65 findings · 23 reviews

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No studies found 15 · 23.1%GRADE not reported 9 · 13.8%Very low 9 · 13.8%Low 12 · 18.5%Moderate 5 · 7.7%High 15 · 23.1%

Vitamin A vs placebo

All‐cause mortality · adults with HIV infection

1 finding from 1 review

Micronutrient supplementation in adults with HIV infection 2017 · Cochrane Headline outcomes only
no estimate extracted
0 studies · 0 participants
GRADE not reported

Vitamin D vs placebo or no intervention

Cancer mortality in trials using vitamin D3 (cholecalciferol) ( · healthy participants or recruited among the general population; individuals diagnosed with a specific disease in a stable phase or with…

Vitamin D may leads to lower cancer mortality in trials using vitamin D₃(cholecalciferol) compared with placebo or no intervention (low certainty).

1 finding from 1 review

Vitamin D supplementation for prevention of cancer in adults 2014 · Cochrane Headline outcomes only
RR 0.88 [0.78, 0.98]
4 studies · 44492 participants
Low

Vitamin A vs placebo

Mortality: lung cancer · healthy people and healthy male physicians

Vitamin A showed no clear difference in mortality: lung cancer compared with placebo (high certainty).

1 finding from 1 review

Drugs for preventing lung cancer in healthy people 2020 · Cochrane Headline outcomes only
RR 1.06 [0.81, 1.38]
3 studies · 190118 participants
High

Vitamin A vs placebo

Mortality: all cancers · healthy people and healthy male physicians

Vitamin A showed no clear difference in mortality: all cancers compared with placebo (high certainty).

1 finding from 1 review

Drugs for preventing lung cancer in healthy people 2020 · Cochrane Headline outcomes only
RR 1.02 [0.88, 1.77]
1 study · 22071 participants
High

Vitamin A vs placebo

Mortality: all causes ‐ smokers and asbestos workers · healthy people and healthy male physicians

Vitamin A leads to higher mortality: all causes ‐ smokers and asbestos workers compared with placebo (high certainty).

1 finding from 1 review

Drugs for preventing lung cancer in healthy people 2020 · Cochrane Headline outcomes only
RR 1.09 [1.05, 1.13]
2 studies · 32883 participants
High

Vitamin A vs placebo or no treatment

Maternal death · pregnant women

Vitamin A alone showed no clear difference in maternal mortality compared with placebo or no treatment (high certainty).

1 finding from 1 review

Vitamin A supplementation during pregnancy for maternal and newborn outcomes 2015 · Cochrane Headline outcomes only
RR 0.88 [0.65, 1.2]
4 studies · 154039 participants
High

Vitamin A vs placebo or no treatment

Perinatal mortality · pregnant women

Vitamin A alone showed no clear difference in perinatal mortality compared with placebo or no treatment (high certainty).

1 finding from 1 review

Vitamin A supplementation during pregnancy for maternal and newborn outcomes 2015 · Cochrane Headline outcomes only
RR 1.01 [0.95, 1.07]
1 study · 76176 participants
High

Vitamin D vs placebo or no intervention

All‐cause mortality · healthy participants or recruited among the general population; individuals diagnosed with a specific disease in a stable phase or with…

Vitamin D may leads to lower all‐cause mortality compared with placebo or no intervention (low certainty).

1 finding from 1 review

Vitamin D supplementation for prevention of cancer in adults 2014 · Cochrane Headline outcomes only
RR 0.93 [0.88, 0.98]
15 studies · 49866 participants
Low

Vitamin E vs placebo

All‐cause mortality · MCI

1 finding from 1 review

Vitamin and mineral supplementation for preventing dementia or delaying cognitive decline in people with mild… 2018 · Cochrane Headline outcomes only
no estimate extracted
1 study · 1 participants
GRADE not reported

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 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 vs placebo

Mortality rate ( · children with acute pneumonia

Vitamin D showed no clear difference in mortality rate ( compared with placebo (low certainty).

1 finding from 1 review

Vitamin D as an adjunct to antibiotics for the treatment of acute childhood pneumonia 2023 · Cochrane Headline outcomes only
RR 0.69 [0.44, 1.07]
3 studies · 584 participants
Low

Staple foods fortified with vitamin A vs same unfortified staple foods

All‐cause mortality · general population over 2 years of age

The review found no eligible studies for this question.

1 finding from 1 review

Fortification of staple foods with vitamin A for vitamin A deficiency 2019 · Cochrane Headline outcomes only
no estimate extracted
Studies not reported
No studies found

Vitamin D vs placebo

All‐cause mortality · adults with HIV infection

It is very uncertain whether vitamin D changes mortality compared with placebo (very low certainty).

1 finding from 1 review

Micronutrient supplementation in adults with HIV infection 2017 · Cochrane Headline outcomes only
RR 1.15 [0.65, 2.02]
1 study · 131 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

Vitamin D vs placebo or no intervention

All‐cause mortality · people with chronic liver diseases

It is very uncertain whether vitamin D changes all‐cause mortality compared with placebo or no intervention (very low certainty).

1 finding from 1 review

Vitamin D supplementation for chronic liver diseases in adults 2021 · Cochrane Headline outcomes only
RR 0.86 [0.51, 1.45]
27 studies · 1979 participants
Very low

Vitamin D vs control

All‐cause mortality · children under 5 years of age

1 finding from 1 review

Vitamin D supplementation for preventing infections in children under five years of age 2016 · Cochrane Headline outcomes only
no estimate extracted
1 study · 3046 participants
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