Vitamin A Research
47 peer-reviewed studies · Evidence score: 9/10
Nonantibiotic prophylaxis for urinary tract infections: a network meta-analysis of randomized controlled trials
Han Z et al. • Infection (2025)
D-mannose, triple therapy, vaccine, probiotics, and cranberry serve as potential nonantibiotic intervention options for clinical UTI prevention.
- Nearly 80% of the RCTs utilized double-blind or triple-blind designs.
- D-mannose, triple therapy, vaccine, probiotics, and cranberry serve as potential nonantibiotic intervention options for clinical UTI prevention.
- Further research warranted to confirm findings
Effects of primary or secondary prevention with vitamin A supplementation on clinically important outcomes: a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis
Bjelakovic G et al. • BMJ open (2024)
Based on moderate certainty of evidence, vitamin A had no effect on mortality in the individually randomised trials.
- Vitamin A did not reduce mortality in individually randomised trials (RR 0.99, 95% CI 0.93 to 1.05; I²=32%; p=0.19; 105 trials; moderate certainty), and this effect was not affected by the risk of bias.
- In individually randomised trials, vitamin A had no effect on mortality in children (RR 0.96, 95% CI 0.88 to 1.04; I²=24%; p=0.28; 78 trials, 178 094 participants) nor in adults (RR 1.04, 95% CI 0.97 to 1.13; I²=24%; p=0.27; 27 trials, 61 880 participants).
- Vitamin A reduced mortality in the cluster randomised trials (0.84, 95% CI 0.76 to 0.93; I²=66%; p=0.0008; 15 trials, 14 in children and 1 in adults; 364 343 participants; very low certainty).
Influence of Vitamin A supplementation on inflammatory biomarkers in adults
Ghannadi S et al. • Scientific Reports (2022)
Vitamin A supplementation may affect inflammatory biomarkers in complex ways.
- 13 RCTs analyzed for CRP and TNF-α
- 9 studies for IL-6
- Complex effects on inflammation
Vitamin and Mineral Supplementation During Pregnancy on Maternal, Birth, Child Health and Development Outcomes in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis
Oh C et al. • Nutrients (2020)
In addition, they further contribute to the ongoing discourse of choosing antenatal MMN over IFA as the standard of care in LMICs.
- IFA supplementation showed notable improvement in maternal anemia and the reduction in low birthweight, whereas LNS supplementation had no apparent effect on outcomes; further research that compares LNS and MMN supplementation could help understand differences with these commodities.
- For single micronutrient supplementation, improvements were noted in only a few outcomes, mainly pre-eclampsia/eclampsia (calcium), maternal anemia (iron), preterm births (vitamin D), and maternal serum zinc concentration (zinc).
- These findings highlight that micronutrient-specific supplementation should be tailored to specific groups or needs for maximum benefit.
Vitamin A supplements for reducing mother-to-child HIV transmission
Wiysonge CS et al. • The Cochrane database of systematic reviews (2017)
Antepartum or postpartum vitamin A supplementation, or both, probably has little or no effect on mother-to-child transmission of HIV in women living with HIV infection and not on antiretroviral drugs.
- Antepartum or postpartum vitamin A supplementation, or both, probably has little or no effect on mother-to-child transmission of HIV in women living with HIV infection and not on antiretroviral drugs.
- The intervention has largely been superseded by ART which is widely available and effective in preventing vertical transmission.
- Further research warranted to confirm findings
Vitamin A supplementation for postpartum women
Oliveira JM et al. • The Cochrane database of systematic reviews (2016)
There was no evidence of benefit from different doses of vitamin A supplementation for postpartum women on maternal and infant mortality and morbidity, compared with other doses or placebo.
- Effects were less certain at six months (risk ratio (RR) 0.50, 95% CI 0.09 to 2.71; 564 participants; 1 RCT; low-quality evidence).
- We found insufficient evidence that vitamin A increases abdominal pain (RR 1.28, 95% CI 0.95 to 1.73; 786 participants; 1 RCT; low-quality evidence).
- We found low-quality evidence that vitamin A supplementation increased breast milk retinol concentrations by 0.20 µmol/L at three to three and a half months (mean difference (MD) 0.20 µmol/L, 95% CI 0.08 to 0.31; 837 participants; 6 RCTs).
Vitamin supplementation for preventing miscarriage
Balogun OO et al. • The Cochrane database of systematic reviews (2016)
Taking any vitamin supplements prior to pregnancy or in early pregnancy does not prevent women experiencing miscarriage.
- Multivitamin supplementation There was evidence of a decrease in the risk for stillbirth among women receiving multivitamins plus iron and folic acid compared iron and folate only groups (RR 0.92, 95% CI 0.85 to 0.99, 10 trials, 79,851 women; high-quality evidence).
- Antioxidant vitamins supplementation There was no evidence of differences in early or late miscarriage between women given antioxidant compared with the low antioxidant group (RR 1.12, 95% CI 0.24 to 5.29, one trial, 110 women).
- Taking any vitamin supplements prior to pregnancy or in early pregnancy does not prevent women experiencing miscarriage.
Overnutrition is a risk factor for iron, but not for zinc or vitamin A deficiency in children and young people: a systematic review and meta-analysis
Tan X et al. • BMJ global health (2024)
Overnutrition is associated with increased risk of ID, but not zinc or VA deficiencies, with an inverted U-shaped relationship observed between iron status and bodyweight.
- Synthesising 16 records of OR from seven eligible studies, overnutrition (overweight and obesity) increased odds of iron deficiency (ID) (OR (95% CI): 1.51 (1.20 to 1.82), p<0.0001, I2=40.7%).
- Odds appeared to be higher for children living with obesity (1.88 (1.33 to 2.43), p<0.0001, I2=20.6%) in comparison to those with overweight (1.31 (0.98 to 1.64), p<0.0001, I2=40.5%), although between group differences were not significant (p=0.08).
- Overnutrition is associated with increased risk of ID, but not zinc or VA deficiencies, with an inverted U-shaped relationship observed between iron status and bodyweight.
Fortification of staple foods with vitamin A for vitamin A deficiency
Hombali AS et al. • The Cochrane database of systematic reviews (2019)
Fortifying staple foods with vitamin A alone may make little or no difference to serum retinol concentrations or the risk of subclinical vitamin A deficiency.
- It is uncertain whether vitamin A alone reduces the risk of subclinical vitamin A deficiency (risk ratio (RR) 0.45, 95% CI 0.19 to 1.05; 2 studies; 993 participants; I² = 33%, very low-certainty evidence).
- The certainty of the evidence was mainly affected by risk of bias, imprecision and inconsistency.It is uncertain whether vitamin A fortification reduces clinical vitamin A deficiency, defined as night blindness (RR 0.11, 95% CI 0.01 to 1.98; 1 study, 581 participants, very low-certainty evidence).
- When compared to no intervention, it is uncertain whether the intervention reduces the risk of subclinical vitamin A deficiency (RR 0.71, 95% CI 0.52 to 0.98; 2 studies; 318 participants; I² = 0%; very low-certainty evidence) .
Interventions for treating oral leukoplakia to prevent oral cancer
Lodi G et al. • The Cochrane database of systematic reviews (2016)
Surgical treatment for oral leukoplakia has not been assessed in an RCT that included a no treatment or placebo comparison.
- Surgical treatment for oral leukoplakia has not been assessed in an RCT that included a no treatment or placebo comparison.
- Nor has cessation of risk factors such as smoking been assessed.
- The available evidence on medical and complementary interventions for treating people with leukoplakia is very limited.
The effect of vitamin supplementation on neurodevelopmental and clinical outcomes in very low birth weight and very preterm infants: A systematic review and meta-analysis
Bronnert A et al. • PloS one (2025)
There are few and inconclusive data on the effect of vitamin supplementation in preterm infants on later neurodevelopment.
- There are few and inconclusive data on the effect of vitamin supplementation in preterm infants on later neurodevelopment.
- Evidence for shorter-term outcomes is mostly of low certainty.
- Together with substantial heterogeneity in trial design, it therefore is difficult to recommend a specific supplementation regimen.
Vitamin A deficiency among pregnant women in Ethiopia: a systematic review and meta-analysis
Eyeberu A et al. • International health (2023)
Nearly one-third of pregnant women in Ethiopia had VAD.
- The overall pooled prevalence of VAD was 29% (95% confidence interval 21 to 36) with I2=99.67% and p<0.001.
- Nearly one-third of pregnant women in Ethiopia had VAD.
- Strengthening intervention modalities that aimed to increase the uptake of vitamin A-rich foods can avert VAD among pregnant women in Ethiopia.
Comparative effectiveness and safety of interventions for acute diarrhea and gastroenteritis in children: A systematic review and network meta-analysis
Florez ID et al. • PloS one (2018)
Most interventions analyzed (except vitamin A, micronutrients, prebiotics, and kaolin-pectin) showed evidence of superiority to placebo in reducing the diarrhea.
- Most interventions analyzed (except vitamin A, micronutrients, prebiotics, and kaolin-pectin) showed evidence of superiority to placebo in reducing the diarrhea.
- With moderate-to high-quality of evidence, SB+ZN and SM+ZN, demonstrated the best combination of evidence quality and magnitude of effect while symbiotics, loperamide and zinc proved being the best single interventions, and loperamide was the most unsafe.
- Nonetheless, the effect of zinc, SB+ZN and SM+ZN might only be applied to children in LMIC.
The Efficacy of Multivitamin, Vitamin A, Vitamin B, Vitamin C, and Vitamin D Supplements in the Prevention and Management of COVID-19 and Long-COVID: An Updated Systematic Review and Meta-Analysis of Randomized Clinical Trials
Sinopoli A et al. • Nutrients (2024)
Better-designed studies are needed to clarify these vitamins' potential effects against SARS-CoV-2.
- Inverse-variance random-effects meta-analyses were conducted to estimate pooled risk ratios (RRs) and 95% confidence intervals (CIs) for all-cause mortality between supplemented and non-supplemented individuals.
- A few positive findings were reported in some vitamin C trials but results were inconsistent in most outcomes, excluding all-cause mortality (RR = 0.84; 95% CI: 0.72-0.97).
- Vitamin D results were mixed in most aspects, including mortality, in which benefits were observed in regular administrations only (RR = 0.67; 95% CI: 0.49-0.91).
Efficacy and Safety of Prophylactic Agents in Prevention of Retinopathy of Prematurity: A Systematic Review and Meta-analysis of Randomised Controlled rials
Batais WT et al. • BMJ open ophthalmology (2024)
Lipids show promise in reducing severe ROP in preterm infants, while vitamin A and propranolol were not effective.
- No significant reduction in ROP incidence at any stage was found in the intervention groups compared with placebo (RR=0.83; 95% CI= (0.69 to 1.00); p=0.05; I²=0%).
- Lipids significantly reduced severe ROP incidence (RR=0.48; 95% CI= (0.28 to 0.80); p=0.005), while vitamin A (RR=1.14; 95% CI= (0.51 to 2.54); p=0.75) and propranolol (RR=0.69; 95% CI= (0.29 to 1.65); p=0.41) did not.
- There were no significant differences in adverse events (RR=0.83; 95% CI= (0.59 to 1.17); p=0.28) or mortality (RR=0.93; 95% CI= (0.67 to 1.30); p=0.68) across all groups.
Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age
Imdad A et al. • The Cochrane database of systematic reviews (2022)
This update identified no new eligible studies and the conclusions remain the same.
- Studies were set in 19 countries: 30 (63%) in Asia, 16 of these in India; 8 (17%) in Africa; 7 (15%) in Latin America, and 2 (4%) in Australia.
- At longest follow-up, there was a 12% observed reduction in the risk of all-cause mortality for VAS compared with control using a fixed-effect model (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.83 to 0.93; high-certainty evidence).
- Nine trials reported mortality due to diarrhoea and showed a 12% overall reduction for VAS (RR 0.88, 95% CI 0.79 to 0.98; 1,098,538 children; high-certainty evidence).
The Relationship of Vitamin A and Neonatal Respiratory Diseases: A Meta-Analysis
Li Y et al. • The clinical respiratory journal (2024)
The Clinical Respiratory Journal published by John Wiley & Sons Ltd.
- The sensitivity analysis results showed that excluding some special article had some effect on the final pooled effect.
- But generally speaking, the result of meta-analysis was stable.
- There is a statistical correlation of vitamin A on the neonatal respiratory diseases from two aspects of etiological exploration and effect evaluation of treatment.© 2024 The Author(s).
Association of variant vitamin statuses and tuberculosis development: a systematic review and meta-analysis
Zhou Y et al. • Annals of medicine (2024)
This meta-analysis indicated that people with tuberculosis exhibited low levels of vitamins A and D, while vitamin D deficiency was identified as a risk factor for tuberculosis.
- The random-effect model showed that people with tuberculosis may exhibit vitamin A deficiency (OR = 10.66, 95%CI: 2.61-43.63, p = .001), while limited cohort studies showed that vitamin A supplementation may reduce tuberculosis occurrence.
- Additionally, vitamin D deficiency was identified as a risk factor for tuberculosis development (RR = 1.69, 95%CI: 1.06-2.67, p = .026), and people with tuberculosis generally had lower vitamin D levels (OR = 2.19, 95%CI: 1.76-2.73, p < .001) compared to other groups.
- This meta-analysis indicated that people with tuberculosis exhibited low levels of vitamins A and D, while vitamin D deficiency was identified as a risk factor for tuberculosis.
Interventions to prevent mother-to-child transmission in breastfeeding mothers with HIV: a systematic review and meta-analysis of randomized controlled trials
Xu F et al. • Revista do Instituto de Medicina Tropical de Sao Paulo (2024)
However, the effectiveness of different ART regimens or other therapies, including high-dose vitamin A, is unclear.
- The postnatal HIV transmission rate was found to be 0.01 (95%CI: 0.00 - 0.02).
- Analysis of funnel plots and Egger's test (p = 0.589) showed no evidence of publication bias.
- The results suggest that the use of ART significantly reduces the risk of postnatal HIV transmission compared with placebo.
From A to E: Uniting vitamins against stroke risk-A systematic review and network meta-analysis
Tripathi S et al. • European journal of clinical investigation (2024)
Our study has established noteworthy connections between vitamin A, vitamin B-complex, vitamin B6, folate, vitamin C, and vitamin D in the realm of stroke prevention.
- Our study has established noteworthy connections between vitamin A, vitamin B-complex, vitamin B6, folate, vitamin C, and vitamin D in the realm of stroke prevention.
- These findings add substantial weight to the accumulating evidence supporting the potential advantages of vitamin interventions in mitigating the risk of stroke.
- However, to solidify and validate these observations, additional research is imperative.