Vitamin A
Vitamin A (Retinol/Beta-Carotene)
An essential fat-soluble vitamin critical for vision, immune function, skin health, and cellular growth.
Vitamin A is an essential fat-soluble vitamin that exists in two primary forms: preformed vitamin A (retinol, found in animal foods) and provitamin A carotenoids (like beta-carotene, found in plants). It's crucial for maintaining healthy vision (especially night vision), immune function, skin integrity, and cellular differentiation. Deficiency is rare in developed countries but can cause night blindness and immune dysfunction.
Mechanisms of Action
Visual Function
Essential for rhodopsin production
Immune Function
Maintains immune barriers and cell function
Gene Expression
Regulates cellular growth and differentiation
Recommended Dose
2500-5000 IU daily (retinol); up to 25000 IU (beta-carotene)
Loading: Not required; avoid high doses
Optimal Timing
- With fat-containing meal
- Any time of day
Take with food
Best Form
Mixed carotenoids or low-dose retinyl palmitate
Alternatives: Beta-carotene (provitamin A), Retinyl acetate, Cod liver oil
Beta-carotene is safer (no toxicity risk) but conversion varies. Preformed vitamin A is more reliable but has toxicity potential.
Duration
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Fat-soluble vitamin; requires dietary fat for absorption. Beta-carotene is safer as body regulates conversion.
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Vision Support
Maintained night vision and eye health
Immune Support
Enhanced immune defenses
Skin Health
Improved skin cell turnover
Toxicity Risk
Fat-soluble; can accumulate to toxic levels
AVOID high-dose retinol; beta-carotene is safer
Avoid high-dose beta-carotene supplements
Who Should NOT Take This
- Pregnancy (high-dose retinol is teratogenic)
- Liver disease
Drug Interactions
Do not combine; risk of vitamin A toxicity
May reduce absorption; take separately
Risk of vitamin A overdose, liver toxicity
Possible Side Effects
Tip: Stay below 10,000 IU/day preformed vitamin A
Tip: Harmless; reduce dose if concerned
Warnings
- Preformed vitamin A can cause birth defects
- Can accumulate to toxic levels
- High-dose beta-carotene linked to lung cancer in smokers
Top studies from 40+ peer-reviewed papers
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.”
Key Findings:
- 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).
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.”
Key Findings:
- 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.
- In addition, they further contribute to the ongoing discourse of choosing antenatal MMN over IFA as the standard of care in LMICs.
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.”
Key Findings:
- 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
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.”
Key Findings:
- 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.
- We do not currently have evidence of a treatment that is effective for preventing the development of oral cancer.
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.”
Key Findings:
- 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).
- Infant: We did not find evidence that vitamin A supplementation reduced infant mortality at two to 12 months (RR 1.08, 95% CI 0.77 to 1.52; 6090 participants; 5 RCTs; low-quality evidence).
Study Type Distribution
Goals This Supplement Supports
Related Goals
This information is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before starting any supplement.