Overview
Nicotinamide riboside (NR) is one of the principal oral NAD+ precursors, sold most widely as Niagen / Tru Niagen by ChromaDex. Mechanistically it enters cells via specific transporters and is phosphorylated by nicotinamide riboside kinases (NRK1/2) to NMN and then to NAD+, bypassing the rate-limiting niacin pathway. Its inclusion in this 'peptide companion' library follows the same logic as NAD+ and NMN — community use stacks NR with peptide regimens, and most competitors lump NR in with peptides without disclosing it isn't one. NR has a substantial human-trial program, more than NMN: oral NR consistently raises blood NAD+ levels in healthy adults at 250–1000 mg/day. The harder question — whether the NAD+ rise drives clinically meaningful changes in metabolic health, cognitive function, or aging biomarkers — has produced largely null or modest results across multiple RCTs.
Mechanism
Enters cells via equilibrative nucleoside transporters (ENT1, ENT4) and the recently characterized SLC12A8 transporter (more relevant for NMN). Phosphorylated by nicotinamide riboside kinase (NRK1 or NRK2) to nicotinamide mononucleotide (NMN), which NMNAT enzymes convert to NAD+. This salvage pathway bypasses the rate-limiting nicotinamide phosphoribosyltransferase (NAMPT) step and produces NAD+ more efficiently than niacin (nicotinic acid) without the flushing.
Evidence by indication
We classify each indication separately. The same peptide can be Tier 1 for one use and Tier 4 for another. Tiers reflect the published literature, not the strength of community framing.
Cardiovascular / vascular function (older adults)
Martens 2018 reported reduced systolic blood pressure (~6 mmHg) and arterial stiffness improvements in middle-aged/older adults with elevated baseline BP. Effect size is modest; a few subsequent trials are mixed. Tier 3.
Raising blood NAD+ levels (biomarker)
Multiple human RCTs (Martens 2018, Trammell 2016, Conze 2019) consistently demonstrate dose-dependent increases in whole-blood NAD+ levels with oral NR at 250–1000 mg/day. The biomarker effect is robust. Tier 2 because the indication is biochemical, not clinical-outcome.
Cognitive performance / brain NAD+
Some MRS imaging studies report measurable brain NAD+ increases with oral NR; clinical cognitive endpoints are mixed. Brink 2022 in Parkinson's reported some symptomatic improvements at 1000 mg/day. Underpowered for definitive conclusions.
Skeletal muscle metabolism / insulin sensitivity
Multiple small RCTs in healthy and prediabetic adults show null to modest effects on insulin sensitivity. Inconsistent findings limit the indication to Tier 3.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
General anti-aging / longevity
Aggressive marketing positions NR as an anti-aging intervention. Evidence is mechanistic and biomarker-level; no longevity outcome trial in humans.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
Studied dose ranges
The ranges below come from published trial protocols where available, and from documented self-experimenter consensus where the literature does not include human dose-finding work. The notes flag which is which.
Human RCTs typically test 250–1000 mg/day. Note the unit math: 1000 mg = 1,000,000 mcg. This is supplement-scale dosing, not microgram-dose peptide territory.
Contraindications
- Pregnancy and breastfeeding (limited safety data at supplement doses)
- Active malignancy — NAD+ metabolism intersects with cancer biology in dose- and tumor-type-dependent ways; consult oncology
- Caution with chemotherapy regimens whose mechanism involves NAD+/PARP signaling
- Known hypersensitivity
Reported side effects
- Generally well tolerated at 250–1000 mg/day
- Mild GI upset (nausea, indigestion)
- Headache
- Flushing (less than niacin/nicotinic acid; sometimes still reported)
- Theoretical: long-term effects of sustained high cellular NAD+ on sirtuin activity, cancer biology, and immune signaling are not fully characterized in humans
Reconstitution & storage
Oral capsule supplement — no reconstitution.
Storage. Room temperature, dry, protected from light. Niagen and similar products typically have 2-year shelf life from manufacture.
Open the peptide calculator → to compute exact draw volumes for your specific vial and BAC water choice.
Editorial note
DRAFT — pending Wayne's review. NR is in the same 'companion supplement, NOT a peptide' bucket as NAD+ and NMN. The biomarker evidence is solid (raises NAD+ reliably); the clinical-outcome evidence is honestly mixed. Editorial position: respect the trials, name what they actually showed, refuse to soften the gap from 'NAD+ went up' to 'aging slowed.' The class field labels it explicitly as NOT a peptide.
Citations
- [1]Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adultsMartens CR, Denman BA, Mazzo MR, et al. · Nature Communications · 2018 · PMID 29467442Foundational human RCT — NR raises NAD+, modest BP/arterial stiffness improvement in older adults. Anchor for biomarker and CV indications.View source
- [2]Safety and metabolism of long-term administration of NIAGEN (nicotinamide riboside chloride) in a randomized, double-blind, placebo-controlled clinical trial of healthy overweight adultsConze D, Brenner C, Kruger CL · Scientific Reports · 2019 · PMID 31604941Long-term safety and pharmacokinetic data for NR in overweight adults — supports the biomarker indication and safety profile.View source
- [3]An exploratory study of the effect of high-dose nicotinamide riboside on motor function in patients with Parkinson diseaseBrink BG, et al. (NR-PD trial) · Nature Medicine · 2022 · PMID 35332179Pilot RCT of high-dose NR in Parkinson's — anchor for Tier 3 cognitive/neurologic indication.View source