○ Evidence tier 4 — Human RCT — biomarker endpoint

Record verify: primary source pending

DesignRandomized, double-blind, placebo-controlled trial (biomarker)
DOI10.1038/s41598-023-29787-3
Citation statusdoi verified via Crossref 2026-07-12 (Sci Rep 2023;13, 'Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial'). PMID + NCT: needs_primary_fulltext.

Five-qualifier claim

Species / populationMiddle-aged and older adults (randomized, placebo-controlled trial).
Exposure, route, scheduleOral NMN (long-term supplementation) over the trial period.
Comparator / durationPlacebo-controlled, double-blind, randomized.
Endpoint / numeric resultChanges in NAD+ metabolism and an arterial-stiffness measure after long-term NMN supplementation.
What it did NOT establishBiomarker/surrogate vascular endpoints — no functional-disability, disease-outcome, or lifespan endpoint.

Primary reference

https://doi.org/10.1038/s41598-023-29787-3

Exact identifier confirmed against the primary record via Crossref/ClinicalTrials.gov where stated in the citation status; anything marked needs_primary_fulltext is not yet confirmed.