# Nicotinamide (NAM)

Nicotinamide (NAM, also called niacinamide) is the amide form of vitamin B3. It is a direct building block for NAD+, via a salvage-pathway enzyme called NAMPT. It is biochemically distinct from the other NAD+ precursors, NMN and NR. NR and NMN feed into the salvage pathway before NAM's entry point. But NAM is also the common waste product when sirtuins, PARPs, and CD38 consume NAD+. So at high levels inside the cell, NAM actually feeds back to inhibit SIRT1 and other sirtuins. That dual role, both precursor and sirtuin brake, makes supplement studies hard to interpret, and sets it apart from NR and NMN. NAM has established medical uses. Topical niacinamide is widely used for your acne and skin barrier. And oral high-dose nicotinamide (500 mg twice a day) cut actinic keratoses and non-melanoma skin cancers in a randomized trial in high-risk but immune-competent adults (Chen et al., 2015, NEJM). But a later phase 3 trial in organ-transplant recipients (ONTRANS; Allen et al., NEJM 2023) found no reduction in skin cancers or keratoses. So the earlier (ONTRAC) result may not generalize to that higher-risk group. Using NAM as a systemic longevity supplement is experimental, and its net effect on sirtuin processes at supplement doses in humans is not established.

## Sources

- Chen AC, Martin AJ, Choy B et al.. (2015). A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention. New England Journal of Medicine. https://doi.org/10.1056/NEJMoa1506197
- Allen NC, Martin AJ, Snaidr VA, et al.. (2023). Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients. New England Journal of Medicine. https://doi.org/10.1056/NEJMoa2203086

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_Canonical: https://longevity-switzerland.com/en/glossary/nicotinamide · Part of Longevity Cities · Updated 2026-06-22_