The NAD-brain pharmacokinetic study of NAD augmentation in blood and brain using oral precursor supplementation.
Level 4 - case-series / case-control
Small non-randomized phase I pharmacokinetic trial without a control group
PubMed 41858901 · doi:10.1016/j.isci.2026.114764
What was done
A phase I pharmacokinetic trial investigated systemic and cerebral NAD dynamics in 12 participants (6 healthy individuals and 6 individuals with Parkinson's disease). Participants received 1,200 mg/day of oral nicotinamide riboside or nicotinamide mononucleotide. Systemic blood and cerebral NAD levels and related metabolites were measured during treatment and after treatment discontinuation.
What was found
The abstract reports directional findings without specific numerical values, percentages, or statistical metrics. Blood NAD increased slowly and reached a plateau after approximately two weeks of treatment, declining with similarly slow kinetics after discontinuation. Cerebral NAD levels increased measurably after four weeks. NAD-related metabolites showed faster increases and washout dynamics compared to NAD itself. High interindividual variability was observed, which was not influenced by sex or disease status.
Why it matters
This study provides human pharmacokinetic data indicating that oral precursor supplementation can raise cerebral NAD, suggesting that brain-targeted clinical regimens require continuous once-daily dosing over at least two to four weeks.
Limits
The sample size is very small (n = 12 total, split between healthy participants and Parkinson's disease, and across two separate precursor drugs). There was no placebo control group, and the abstract reports no quantitative values, baseline levels, effect sizes, or formal pharmacokinetic parameters.
Cited by
- supports Imaging experiments show that oral NAD precursor supplementation increases NAD levels in the human brain.