Phase 1 Trial Maps How NR and NMN Reach the Brain After Supplementation
A completed pharmacokinetic study tracks NAD precursors NR and NMN from bloodstream to brain, filling a critical gap in human data.
Summary
NAD+ levels in the brain decline with age, potentially contributing to cognitive decline and neurodegeneration. While supplements like Nicotinamide Riboside (NR) and Nicotinamide Mononucleotide (NMN) can raise NAD+ in the blood, it has remained unclear whether they actually reach the brain in meaningful amounts. The NAD-brain trial, sponsored by Haukeland University Hospital in Norway, set out to answer this directly by measuring both blood and brain pharmacokinetics in healthy participants during Phase 1 testing. This is one of the first studies to rigorously track NAD replenishment therapy all the way into brain tissue, making it a landmark effort for anyone interested in using these supplements to support cognitive health and brain aging. Full results are not yet publicly available from the abstract alone.
Detailed Summary
NAD+ is a coenzyme central to cellular energy metabolism, DNA repair, and the activity of longevity-associated proteins called sirtuins. Levels of NAD+ fall significantly with age in most tissues, including the brain, and this decline has been linked to neurodegeneration, cognitive impairment, and reduced resilience to metabolic stress. Supplementing with NAD+ precursors such as Nicotinamide Riboside (NR) and Nicotinamide Mononucleotide (NMN) has gained enormous popularity as a strategy to restore these levels, but a fundamental question has persisted: do these compounds actually cross into the brain?
The NAD-brain study, a Phase 1 pharmacokinetic trial sponsored by Haukeland University Hospital in Norway, was designed specifically to address this gap. Enrolling healthy adult participants, the trial measured NAD-related metabolite levels in both blood and brain following oral supplementation with NR or NMN. This dual-compartment measurement approach is methodologically significant, as previous human trials have focused almost exclusively on blood or peripheral tissue NAD+ levels.
The trial has been listed as completed on ClinicalTrials.gov, though detailed results and outcome data have not yet been published in a peer-reviewed journal based on currently available information. The completion of the study itself is an important milestone, as pharmacokinetic data from brain tissue — likely obtained via cerebrospinal fluid sampling or advanced neuroimaging techniques — would provide the field with direct human evidence on central nervous system bioavailability.
If results confirm that NR or NMN meaningfully elevate brain NAD+ levels, this would strengthen the scientific rationale for using these supplements in strategies targeting brain aging, Alzheimer's disease prevention, and neuroprotection. Conversely, limited brain penetration would redirect focus toward delivery optimization or alternative compounds.
The study's caveat is that only the abstract is currently available, meaning no efficacy or safety outcomes can yet be evaluated. Clinicians and researchers should watch for the full publication.
Key Findings
- Phase 1 trial directly measured NAD+ levels in both blood and brain after NR or NMN supplementation in healthy adults.
- Study is now completed, making it one of the first human trials to assess brain bioavailability of NAD precursors.
- Results could confirm or challenge the assumption that oral NR and NMN meaningfully elevate brain NAD+ levels.
- Dual blood-and-brain pharmacokinetic design sets a new methodological standard for NAD supplement research.
- Full peer-reviewed results not yet published; findings remain pending public release.
Methodology
This is a Phase 1 pharmacokinetic study in healthy volunteers comparing NR and NMN supplementation, with NAD+ metabolite levels measured in both blood and brain compartments. The dual-compartment design likely involved cerebrospinal fluid collection or neuroimaging to assess central nervous system penetration. Sponsored by Haukeland University Hospital in Norway and registered on ClinicalTrials.gov (NCT05698771).
Study Limitations
This summary is based on the abstract only, as the full study results are not publicly available; no outcome, safety, or efficacy data can be assessed at this time. The trial enrolled only healthy participants, so findings may not generalize to individuals with neurological conditions or age-related cognitive decline. Study design details, dosing protocols, and brain measurement methodology remain undisclosed pending publication.
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