Supplement analysis backed by scientific evidence · PT

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Moderate evidenceJoints & skin

Niacinamide

Niacinamide (nicotinamide) is the non-flushing amide form of vitamin B3, and at 500 mg twice daily it cut new skin cancers by about 23% in high-risk immunocompetent patients. That is its one strong indication — it failed in transplant recipients, and it does not do what niacin does for cholesterol.

What the science says

  • Prevents non-melanoma skin cancer in high-risk immunocompetent adults Moderate evidence

    The phase 3 ONTRAC trial randomised 386 people with at least two keratinocyte cancers in the previous five years to 500 mg nicotinamide twice daily or placebo for 12 months. New non-melanoma skin cancers fell by 23% (95% CI 4–38%, p=0.02), with actinic keratoses down 11–20%. The benefit disappeared within six months of stopping, so it is suppression rather than cure — and it rests on one well-conducted trial, not a body of them.

  • Prevents skin cancer in organ transplant recipients Moderate evidence

    ONTRANS tested the identical regimen (500 mg twice daily for 12 months) in 158 solid-organ transplant recipients and was stopped early for futility: new keratinocyte carcinomas were essentially identical between groups. Immunosuppressed patients — the highest-risk group of all — are exactly where this does not work, which is a useful check on how far the ONTRAC result generalises.

  • Topical niacinamide improves acne Limited evidence

    A Cochrane-based review of evidence-based topical acne treatments found 4% niacinamide gel roughly comparable to 1% clindamycin in a handful of small, short trials, with low-certainty evidence throughout. This applies to topical application, not the oral capsules — no good trial shows oral niacinamide clears acne.

  • Is a substitute for niacin for cholesterol Strong evidence

    It is not. Nicotinamide lacks activity at GPR109A, which is why it does not flush — and also why it has none of nicotinic acid's lipid effects. It does not raise HDL or lower LDL or lipoprotein(a). If a product markets a 'flush-free' B3 for cholesterol, the absence of flushing is the signal that it will not work for that purpose.

Dosage & safety

Studied doseSkin-cancer chemoprevention trials used 500 mg twice daily (1 g/day total) for 12 months. The RDA for niacin equivalents is 14–16 mg/day and B-complex products typically supply 20–50 mg. Topical formulations are 2–5%. Doses in the multi-gram range have been used experimentally but carry hepatic risk. Niacinamide is not stored, so the twice-daily split in the trials matters.
SafetyNo flushing, which is its main practical advantage over nicotinic acid. Hepatotoxicity has been reported at gram-level daily doses, particularly above 3 g/day — liver enzymes are worth checking on long-term 1 g/day use. Nausea and headache occur. In dialysis patients given 1–1.5 g/day as a phosphate binder, thrombocytopenia and GI effects were common. Very high doses consume methyl groups and can raise homocysteine. Interacts with carbamazepine (raised levels reported). Anyone taking 1 g/day for skin-cancer prevention should be doing so under dermatology follow-up, not instead of it — and sun protection and lesion surveillance remain the primary intervention. Not banned in sport.

Scientific references

Where to buy

NOW Foods, Niacinamide, 500 mg, 100 Veg Capsules

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