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Head-to-head evidence comparison — which supplement is right for you?
Nicotinamide vs Vitamin C: Vitamin C has the stronger overall evidence (8 vs 5.5/10); they're alternatives for improve skin health — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Vitamin C wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Too few graded studies
2 of 2 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
8 of 11 studies with measurable effects showed benefit.
Top outcomes
500mg twice daily
Morning and evening with meals
Niacinamide tablets (500mg)
500-1000mg
With meals, Split doses if taking >500mg
Ascorbic acid or buffered vitamin C
3-12 months
8 weeks
Days
First days
Ongoing
1-2 weeks
4-8 weeks
With high doses (>2g)
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
Vitamin C supplementation for prevention and treatment of pneumonia.
The Cochrane database of systematic reviews (2021) · Systematic review · n=2655
Five studies with 2655 participants (2 RCTs, 3 quasi-RCTs). Three included children under five, one school-aged children and one adults.
Vitamin C supplementation in pregnancy
The Cochrane database of systematic reviews (2015) · Meta analysis · n=24300
29 trials involving 24,300 pregnant women.
Enhanced Vitamin C Delivery: A Systematic Literature Review Assessing the Efficacy and Safety of Alternative Supplement Forms in Healthy Adults
Nutrients (2025) · Systematic review
Most studies (77%) had a low risk of bias.
Vitamin C has a higher evidence score (8/10 vs 5.5/10) and wins in 2 of 3 categories.
For improve skin health, Vitamin C has a higher relevance score (75 vs 68).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
AREDS2 works for diagnosed AMD; lutein/screen-strain claims are weaker. Who actually benefits.
CoQ10, zinc, selenium, carnitine modestly help sperm parameters — but live-birth evidence is weak.
Zinc timing, vitamin D, the real vitamin C effect — and the elderberry caution.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.