NAD+ Precursor
NamNicotinamide
The cheap, flush-free B3 that most Nam → NAD+ routes lead to.
Nicotinamide is the amide form of vitamin B3 and the final product of most NAD+ catabolism. It re-enters the salvage pathway via NAMPT. While it reliably raises NAD+, it also inhibits sirtuins at high doses — a pharmacological trade-off.
What are the pharmacokinetics of Nam?
- Half-life
- ~4 hours
- Time to peak (Tmax)
- 30-60 min
- Clearance
- Hepatic methylation to MNA, urinary excretion
Nicotinamide is the least expensive and most predictable oral NAD+ precursor by pharmacokinetics, but the dose-dependent sirtuin inhibition makes it less favored in longevity protocols than NR or NMN.
What doses of Nam have been studied?
Typical use
500-1,000 mg/day for NAD+ elevation
Clinically studied
Up to 3,000 mg/day in dermatology trials (chemoprevention)
Safety ceiling
3,000 mg/day; hepatotoxicity risk above this threshold
How can Nam be delivered?
Which mechanisms does Nam affect?
What does the research on Nam show?
Journal of Biological Chemistry · 2002 · PMID 12235142
Nicotinamide inhibits sirtuin-mediated deacetylation through non-competitive feedback
Bitterman KJ, et al.
Established that nicotinamide is a product-feedback inhibitor of sirtuins — the paper that motivated the shift to NR and NMN.
DOI 10.1074/jbc.M205670200(opens in new tab)
Frequently asked questions
- How does NAD+ decline with age?
- Tissue NAD+ concentrations drop by roughly 50% between age 20 and 70 in measured human tissues. The decline is driven primarily by rising CD38 activity (an NAD+-hydrolyzing enzyme), reduced NAMPT expression, and increased PARP activation from accumulated DNA damage.
- What is the optimal NMN or NR dosage?
- Published human trials use 250-1,000 mg/day for both NMN and NR. The dose-response for NAD+ elevation plateaus around 500-600 mg/day in most studies — higher doses raise blood NAD+ further but with diminishing tissue-level returns. There is no established clinical dose for longevity outcomes.
- Is long-term NAD+ supplementation safe?
- Short-term (up to 12 weeks) NMN and NR supplementation at studied doses shows a favorable safety profile with no serious adverse events in published trials. Long-term (multi-year) human safety data does not yet exist. Known considerations include methyl donor depletion, potential sirtuin inhibition at very high nicotinamide doses, and unclear interactions with some chemotherapies.
- What is NAD+ and why does it matter?
- NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell. It shuttles electrons in metabolic reactions (the NAD+/NADH redox pair), and it fuels three critical enzyme families: sirtuins (deacylases governing longevity), PARPs (DNA damage sensors), and CD38 (immune signaling).
- Should NMN be taken sublingually or orally?
- Sublingual NMN bypasses gut degradation and first-pass liver metabolism, producing faster and higher peak plasma concentrations than oral capsules in the available human pharmacokinetic data. For most users, sublingual routes deliver more NMN to tissues per milligram dosed — though oral remains cheaper and more convenient.