Master cellular longevity through NAD+ science
The definitive, peer-reviewed knowledge base for Nicotinamide Adenine Dinucleotide (NAD+). Analyze molecular mechanisms, compare bioavailability across precursors, and track active clinical trials — rigorously reviewed, evidence-graded, and independent.
- Peer-reviewed papers
- 400+
- Precursors analyzed
- 5
- Comparison matrix
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Knowledge Matrix
Navigate the empirical data structures.
Knowledge Directory
Comprehensive breakdown of NAD+ precursors (NR, NMN, Nam, NA), their pharmacokinetic profiles, and cellular mechanisms.
Access directoryLive Comparison Matrix
Cross-reference NR, NMN, and NAD+ on bioavailability, pharmacokinetics, regulatory status, and clinical validation.
View matrixPrecursor Profiles
5 individually profiled NAD+ precursors with dosage ranges, half-life, delivery routes, and citation trails.
Browse precursorsLatest Clinical Breakthroughs
Curated summaries of recently published, peer-reviewed studies on NAD+ biosynthesis, precursor pharmacokinetics, and longevity metabolomics.
Read researchWhat is NAD+?
Nicotinamide adenine dinucleotide (NAD+) is a coenzyme present in every living cell. It shuttles electrons during energy metabolism, acts as the required substrate for three enzyme families central to aging — sirtuins, PARPs, and CD38 — and declines measurably with age across most human tissues. NAD+ cannot be supplemented directly with high oral bioavailability, so most interventions deliver precursors the body converts intracellularly.
For the full primer with citations and evidence grading, see our NAD+ primer.
Top questions
Answer-first responses to what you came here to ask.
Is NR or NMN better for raising NAD+?
Both reliably raise blood NAD+ at studied doses. NMN has a dedicated intestinal transporter (Slc12a8) and higher sublingual bioavailability, while NR has the longer human safety record and the most published placebo-controlled trials. Neither has been shown superior in head-to-head human data.
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.