What is the evidence for NMN and NAD+ supplements for longevity?

NMN (nicotinamide mononucleotide) and other NAD+ precursors have compelling animal model evidence for longevity benefits through NAD+ restoration (improving sirtuin activity, mitochondrial function, and DNA repair), but human clinical trials are short-term, small, and have shown NAD+ level increases in blood without demonstrated clinical longevity or disease outcomes, placing NMN in the Theoretical (4) category for human longevity benefit (Yoshino et al., Science, 2021).

David Sinclair's Harvard lab and the broader NAD+ research community have done genuinely interesting work. The problem is the gap between mouse models and human outcomes, mice have shorter lifespans, different metabolic scaling, and are typically inbred strains that do not represent human genetic diversity. NAD+ does decline with age in humans. Whether exogenous NMN supplementation corrects this decline in ways that translate to lifespan or healthspan benefit in humans, rather than just a blood biomarker change, is currently unknown. The products are expensive ($80–$150/month), the human evidence is preliminary, and the marketing significantly outpaces the evidence.

Honesty Scale: Theoretical (4) for NMN/NAD+ longevity benefits in humans. The mechanism is plausible and animal data is compelling; human trial outcomes are not yet established.

What to do: Do not purchase NMN supplements at their current premium price based on animal data and biomarker changes. Invest the same money in a gym membership (zone 2 training increases NAD+ through endogenous mechanisms), sleep quality, and evidence-Solid (1) supplements. If human RCT evidence emerges with clinical outcome data, this position will be updated.

For the full picture, read The Supplementation Deep Dive