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Head-to-head evidence comparison — which supplement is right for you?
Vitamin A wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
2 of 3 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
9 of 18 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Nicotinamide and Vitamin A have evidence — compare verdict strength side-by-side.
500mg twice daily
Morning and evening with meals
Niacinamide tablets (500mg)
2500-5000 IU daily (retinol); up to 25000 IU (beta-carotene)
With fat-containing meal, Any time of day
Mixed carotenoids or low-dose retinyl palmitate
3-12 months
8 weeks
Days
First days
2-4 weeks
2-4 weeks
4-8 weeks
With chronic excess
A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention.
The New England journal of medicine (2015) · Rct · n=386
ONTRAC: phase-3, double-blind RCT randomizing 386 patients with ≥2 prior non-melanoma skin cancers to 500 mg nicotinamide twice daily or placebo for 12 months
Skin Cancer Prevention and Antiaging: Role of Nicotinamide.
International journal of molecular sciences (2026) · Review
Review of the biological rationale and clinical evidence for nicotinamide and NAD+ precursors in photoaging and cutaneous carcinogenesis
Topical nicotinamide compared with clindamycin gel in the treatment of inflammatory acne vulgaris.
International journal of dermatology (1995) · Rct · n=76
Double-blind RCT of 76 patients randomized to 4% nicotinamide gel or 1% clindamycin gel twice daily for 8 weeks for moderate inflammatory acne
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
BMJ open (2024) · Meta analysis · n=672
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.
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
Nutrients (2020) · Meta analysis · n=451723
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.
Vitamin A supplements for reducing mother-to-child HIV transmission
The Cochrane database of systematic reviews (2017) · Meta analysis · n=6601
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 ONTRAC RCT used 500 mg twice daily (1000 mg/day total) and reduced new non-melanoma skin cancers by 23%. Effect requires continuous use; it disappeared after discontinuation. Curve is indicative — only the 1000 mg/day regimen is directly RCT-supported.
AI-estimated from published studies. Interpret as directional guidance.
Vitamin A has a higher evidence score (7/10 vs 5.5/10) and wins in 2 of 3 categories.
For healthy aging, Vitamin A has a higher relevance score (80 vs 50).
No known interactions between Nicotinamide and Vitamin A have been documented in our database. However, always consult a healthcare provider before combining supplements.