NMN / NAD+ precursors

Tier 3 — weak evidence · Anti-aging / Longevity

Regulatory note: the FDA excluded NMN from supplements in 2022, then on 29 September 2025 concluded it is not excluded, because it was marketed as a supplement before the drug investigations. Sellers still have to meet new-dietary-ingredient rules. NMN and nicotinamide riboside are sold to boost NAD+, a cellular fuel that drops with age. The biology checks out: 2024–2026 meta-analyses confirm oral NMN reliably raises blood NAD+ within 2–4 weeks and is well tolerated. Whether that translates into feeling or functioning better is a different story. A 2025 meta-analysis in older adults…

Dose: 250–1,200 mg/day has been tested in trials; no established optimal dose. Blood NAD+ rises reliably within 2–4 weeks, but clinical benefits are small and inconsistent, so no dose–response sweet spot has been confirmed.