NAD+

This widely-cited review synthesizes the in vivo evidence for NAD+ precursors and other NAD+-boosting molecules across animal models of aging and metabolic stress. The authors describe NAD+ as a hub coenzyme that couples redox metabolism (NAD+/NADH balance, ATP generation) to the activity of NAD+-consuming enzymes — particularly the sirtuin deacylases (SIRT1–SIRT7), PARPs, and CD38. The review compiles preclinical data on nicotinamide riboside (NR), nicotinamide mononucleotide (NMN), nicotinic acid, and nicotinamide, summarizing reported effects on mitochondrial function, insulin sensitivity, vascular biology, and neuronal NAD+ pools in rodent models. The authors discuss the age-related decline in tissue NAD+ and the rationale for studying NAD+ repletion as a research target, while noting that translation from animal models to humans requires further controlled study.

NAD+ is a small molecule that every cell uses to shuttle electrons during energy production. It also acts as a fuel for a family of enzymes called sirtuins, which scientists study in connection with cellular aging. In animal studies, NAD+ levels drop in many tissues as the animal ages. This review collects the evidence from rodent studies where researchers gave NAD+ precursor molecules to animals and measured what happened to their cells. The authors describe consistent patterns across studies — improvements in mitochondrial measurements, metabolic markers, and stress responses — while emphasizing that these are animal findings and that human research is still in earlier stages.

This study reports the first-in-human pharmacokinetic characterization of an NAD+ precursor, nicotinamide riboside (NR), alongside parallel mouse data. In mice, oral NR produced distinct and superior hepatic NAD+ pharmacokinetics compared with equimolar doses of nicotinic acid and nicotinamide. In a clinical pharmacokinetic study, single oral doses of 100, 300, and 1000 mg of NR produced dose-dependent increases in the blood NAD+ metabolome in healthy adults. The authors also identified nicotinic acid adenine dinucleotide (NAAD) as a previously unappreciated metabolite formed from NR, and reported that NAAD elevation is a highly sensitive biomarker of effective NAD+ repletion. The study established that oral NAD+ precursors can elevate the blood NAD+ metabolome in humans in a dose-responsive way, providing a framework for downstream research into NAD+ pool dynamics.

Scientists wanted to know whether taking an NAD+ precursor by mouth would actually raise NAD+ levels in the body. They tested a molecule called nicotinamide riboside (NR) in both mice and healthy human volunteers. In mice, NR raised NAD+ in the liver more than two other forms tested. In humans, single oral doses produced dose-dependent increases in NAD+ and related metabolites measured in the blood, with bigger doses producing bigger rises. The researchers also discovered a related molecule, NAAD, that turned out to be a sensitive marker for tracking whether an NAD+ booster was actually working. This study laid the groundwork for measuring NAD+ pool changes in human research.