Niacinamide
The amide form of vitamin B3 — a clean, non-flushing NAD+ precursor that bypasses the GPR109A-mediated flush of niacin. | Compound
Aliases (4)
▸ Overview TL;DR
The amide form of vitamin B3 — a clean, non-flushing NAD+ precursor that bypasses the GPR109A-mediated flush of niacin. At low doses (50-100 mg) it is general B-vitamin coverage; at high doses (500-1500 mg) it has been studied for skin (oral nicotinamide reduces non-melanoma skin cancer recurrence in the ONTRAC trial), early Alzheimer's (Phase 2), and as a NAD+ precursor for longevity. For Dylan: the low-dose form is fine insurance; the high-dose protocol is not currently justified.
▸ Mechanism of action
Niacinamide enters cells passively and is converted to NAD+ via the salvage pathway:
NAM → NMN (via NAMPT) → NAD+ (via NMNAT)
NAD+ is the cofactor for ~500 enzymes including:
- Sirtuins (SIRT1-7): NAD+-dependent deacetylases involved in metabolic regulation, mitochondrial biogenesis, and longevity. SIRT activity falls with age tracked by NAD+ decline.
- PARP enzymes: Use NAD+ for DNA-damage repair. Heavily activated PARPs (in stress, inflammation, age) deplete cellular NAD+.
- CD38: NAD+-degrading ectoenzyme that climbs with age — apigenin inhibits this.
- Mitochondrial complex I: NAD+/NADH redox cycle is the engine of oxidative phosphorylation.
Difference from niacin (nicotinic acid):
- Niacinamide does NOT activate GPR109A → no prostaglandin-mediated flush
- Niacinamide does NOT lower lipids (the lipid effect of niacin is GPR109A-mediated)
- Both raise NAD+, but niacinamide is the cleaner cosmetic/supplement form
Difference from NMN/NR:
- NMN and NR are downstream intermediates that bypass the rate-limiting NAMPT step
- Theoretically more efficient per mg, but recent PK work shows much of oral NMN/NR is broken back down to NAM in the gut and liver before reaching cells
- Niacinamide may be ~equivalent to NMN/NR for raising tissue NAD+ at a fraction of the cost — controversial but supported by Trammell 2016 and Liu 2018 mouse data
The "high-dose nootropic" hypothesis: At 500-1500 mg/day, niacinamide may achieve sufficient brain NAD+ elevation to drive measurable SIRT and mitochondrial benefit. Supported by some Alzheimer's-model rodent data and the 2020s skin-cancer literature.
▸ Pharmacokinetics No data
▸ What to expect Generic
- 1Week 1Tolerability and dose-response.
- 2Week 2-4Early effect window.
- 3Week 4-8Peak benefit assessment.
- 4Week 8+Cycle decision point.
▸ Side effects + safety
- Common (>10% users): None at supplemental doses. Exceptional safety profile.
- Less common (1-10%): Mild GI discomfort at >500 mg; mild flushing or warmth in sensitive users
- **Rare-serious (<1%):** Hepatotoxicity at >3 g/day chronic. Insulin resistance signal in some studies at >1.5 g/day chronic — clinically modest but real.
- Methyl-donor depletion: Chronic high-dose niacinamide is methylated to N-methyl-nicotinamide for excretion, consuming SAMe and methyl groups. Theoretical homocysteine elevation if folate/B12 status is suboptimal.
- Specific watch periods: Monitor ALT/AST + glucose + HbA1c if dosing >1 g/day for >3 months.
▸Interactions6 compounds
- NMN, NR:SynergisticSame NAD+ pathway from different angles; some users stack all three at lower doses each. Not strictly necessary but logical.
- Apigenin:SynergisticCD38 inhibition (apigenin) + NAD+ supply (niacinamide) — Sinclair-lab-style NAD+ stack covering both supply and preservation.
- B12, folate, methyl donors:SynergisticCounterbalance methyl-group demand at high doses.
- Resveratrol, pterostilbene:SynergisticSIRT activator co-stack — speculative but logical.
- Carbidopa, isoniazid:AvoidBoth interact with B6/B3 metabolism; clinically minor for niacinamide vs niacin.
- Other high-dose flushing niacin:AvoidRedundant.