Niacinamide is a non-flushing vitamin B3 used to rebuild a core energy and repair molecule. The human signal is not lifespan extension but fewer new common non-melanoma skin cancers among people with a working immune system and prior skin cancers at one gram per day. That finding disappeared after organ transplant. Unproven as a general longevity drug. (Full Review)
| Marker | Target | Why |
|---|---|---|
| ALT / AST | Often <25 U/L; stop or reduce if >3× ULN | Detect hepatotoxicity at high dose |
| Platelets | Track change from personal baseline; conventional 150–400 ×10⁹/L | Dialysis trials reported thrombocytopenia |
| Homocysteine | Functional often <8 μmol/L; conventional <15 | Proxy for methyl-donor strain from NNMT |
| HbA1c | Functional often 4.8–5.3%; conventional <5.7% | High-dose series reported minor insulin-resistance signals |
| Whole-blood NAD+ | No established target; track change from own baseline | Confirms precursor engagement |
| Skin examination | Individual's new keratinocyte-cancer and actinic-keratosis counts | The ONTRAC clinical endpoint |
Cadence: Labs at 3 months, then every 6–12 months at 1 g/day if enzymes are stable; sooner above 1.5 g/day, with liver disease, or on dialysis. Dermatology review every 3–12 months if chemoprevention is the goal.