NR (Nicotinamide Riboside)
A vitamin B3-derived NAD+ precursor sold as a supplement (e.g. Niagen). It is among the best-studied NAD+ boosters in humans, reliably and dose-dependently raising blood NAD+, but placebo-controlled trials have generally failed to show meaningful improvements in metabolic or functional aging endpoints.
01 Overview
Nicotinamide riboside is a pyridine nucleoside form of vitamin B3 that raises NAD+ through the salvage pathway. It has generally recognised as safe (GRAS) status in the US and is the most trialed NAD+ precursor, with multiple randomised, placebo-controlled human studies.
Across those trials NR is safe and dose-dependently elevates blood NAD+ (commonly doubling it at 500-1000 mg/day), but effects on insulin sensitivity, blood pressure, mitochondrial function, inflammation, and physical performance have been small or null. Animal data are more encouraging for muscle, metabolic, and neuroprotective endpoints. As with all NAD+ precursors, no human study has shown an effect on lifespan or age-related disease incidence.
02 Mechanism
Enters cells and is phosphorylated by NRK kinases to NMN, then converted to NAD+, augmenting the salvage pathway that sustains sirtuin and PARP activity.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common | 300–500 mg/day | Oral | Typical consumer dose; reliably raises NAD+. |
| High trial dose | 1000–2000 mg/day | Oral | Doses up to 2000 mg/day studied and tolerated in trials. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Dose-dependent NAD+ elevationConsistently and dose-dependently raises whole-blood NAD+ in randomised human trials. | up to ~2x blood NAD+ | Clinical | |
| Reduced circulating inflammatory markersSome trials report lowered pro-inflammatory cytokines; findings are inconsistent across cohorts. | modest | Clinical | |
| Neuroprotective / metabolic benefit (animal)Improves mitochondrial and neuronal outcomes in rodent models of aging and neurodegeneration. | moderate | Preclinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Flushing / itchingMild flushing or pruritus occasionally reported, less than with plain niacin. | Mild | Uncommon | Clinical | |
| GI discomfortNausea, bloating, or dyspepsia occasionally reported at higher doses. | Mild | Uncommon | Clinical |