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NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every cell of your body, essential for energy metabolism, DNA repair, and the activity of sirtuins—proteins strongly linked to longevity. Its levels decline dramatically with age, and that decline appears to accelerate many hallmarks of aging. The good news: precursors like NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) can meaningfully raise NAD+ levels in humans. The harder question: does raising them actually extend healthspan?
Evidence Assessment
Evidence Strength
Moderate
Study Type
Clinical Review
Confidence
High
Key Findings
- NAD+ levels drop ~50% between age 25 and 55 in human muscle tissue
- NMN (250mg/day) improved muscle insulin sensitivity in postmenopausal women (Yoshino et al., Science 2021)
- CD38 enzyme drives much of age-related NAD+ decline and is worsened by chronic inflammation
- Exercise activates NAMPT, the rate-limiting enzyme in NAD+ biosynthesis
Practical Takeaways
- 250–500mg NMN or NR daily is the best-studied supplementation range
- Exercise is the most potent free way to boost endogenous NAD+ production
- Quercetin (500mg/day) may inhibit CD38 and enhance NAD+ levels
Limitations & Caveats
- Long-term human RCT data is lacking
- Theoretical cancer concern unresolved
- Consult oncologist if active cancer