NAD+

Nicotinamide adenine dinucleotide (NAD+) is an essential coenzyme present in every living cell. It is central to energy metabolism (glycolysis, the TCA cycle, oxidative phosphorylation) where it shuttles electrons as NAD+/NADH, and it is also consumed as a substrate by enzymes such as sirtuins, PARPs (DNA repair), and CD38. Tissue NAD+ is reported to decline with age, which has made restoring NAD+ a prominent target in longevity research. Most human evidence concerns oral NAD+ precursors rather than NAD+ itself, chiefly nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). These precursors reliably raise blood NAD+ in trials and are generally well tolerated, but translation into clear functional benefits (strength, cognition, metabolic markers) has so far been modest and inconsistent. NAD+ administered directly is used clinically and in wellness clinics mainly as slow intravenous (IV) infusion, and increasingly as compounded subcutaneous/intramuscular injection. Pharmacokinetic work shows IV NAD+ is rapidly taken up and broken down into metabolites rather than circulating intact, which complicates interpretation of how much usable NAD+ a dose actually delivers. This profile is for research and educational reference only. NAD+ and its precursors are not approved drugs for anti-aging, and injectable NAD+ products are typically compounded rather than FDA-approved.