Nicotinamide Riboside is Uniquely Bioavailable in People and Mice

Nicotinamide riboside (NR) is in wide use as an NAD+ precursor vitamin. Here we conducted experiments to determine the time and dose-dependent effects of NR on blood, liver and heart NAD+ metabolism in people and mice. We report that human blood cell NAD+ can rise as much as 2.7-fold with a single dose of NR, that NR elevates mouse hepatic NAD+ with distinct and superior pharmacokinetics to those of nicotinic acid (NA) and nicotinamide (Nam), and that single doses of 100, 300, and 1000 mg of NR provide a dose-dependent increase in the blood cell NAD+ metabolome in the first clinical trial of NR pharmacokinetics. We also report that nicotinic acid adenine dinucleotide (NAAD), which was not thought to be en route for conversion of NR to NAD+, is formed from NR and that the rise in NAAD is a highly sensitive biomarker of effective NAD+ supplementation.