Acute nicotinamide riboside supplementation increases human cerebral NAD+ levels in vivo

Purpose: The purpose of this study was to determine the effect of acute nicotinamide riboside (NR) supplementation on cerebral nicotinamide adenine dinucleotide (NAD(+)) levels in the human brain in vivo by means of downfield proton MRS (DF H-1 MRS). Methods: DF H-1 MRS was performed on 10 healthy volunteers in a 7.0 T MRI scanner with spectrally selective excitation and spatially selective localization to determine cerebral NAD(+) levels on two back-to-back days: once after an overnight fast (baseline) and once 4 h after oral ingestion of nicotinamide riboside (900 mg). Additionally, two more baseline scans were performed following the same paradigm to assess test-retest reliability of the NAD(+) levels in the absence of NR. Results: NR supplementation increased mean NAD(+) concentration compared to the baseline (0.458 +/- 0.053 vs. 0.392 +/- 0.058 mM; p<0.001). The additional two baseline scans demonstrated no differences in mean NAD(+) concentrations (0.425 +/- 0.118 vs. 0.405 +/- 0.082mM; p=0.45), and no difference from the first baseline scan (F(2, 16) = 0.907; p=0.424). Conclusion: These preliminary results confirm that acute NR supplementation increases cerebral NAD(+) levels in healthy human volunteers and shows the promise of DF H-1 MRS utility for robust detection of NAD(+) in humans in vivo.