About NAD+ 500mg

Nicotinamide adenine dinucleotide (NAD+) is a coenzyme present in every living cell, serving as a critical mediator of energy metabolism and cellular signalling. First identified by Arthur Harden and William Young in 1906 during their studies on yeast fermentation, NAD+ has since been recognised as one of the most fundamental molecules in biology. It participates in redox reactions across the core metabolic pathways — glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation — shuttling electrons between reactions that convert nutrients into usable cellular energy.

Beyond its metabolic role, NAD+ functions as a substrate for several classes of signalling enzymes that regulate DNA repair, gene expression, stress responses, and circadian rhythm. This dual identity — as both a metabolic workhorse and a signalling molecule — has made NAD+ a focal point of research into ageing, cellular resilience, and metabolic dysfunction. A well-documented decline in NAD+ levels with age has driven substantial research interest in understanding both the causes of this decline and its functional consequences across tissues and organ systems.

NAD+ is supplied at 500mg in its direct, oxidised form for use in research applications. This distinguishes it from precursor compounds such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), which require enzymatic conversion before entering NAD+ pools. For researchers investigating NAD+-dependent processes in cell-free systems, enzyme assays, or direct supplementation studies, the direct form offers a way to bypass biosynthetic conversion steps entirely. This product is for research use only.

Research Summary

The metabolic role of NAD+ has been understood in broad terms for over a century, but the modern era of NAD+ research began with the discovery that it serves as an essential substrate for sirtuins — a family of NAD+-dependent deacetylase and ADP-ribosyltransferase enzymes. Pioneering work by Leonard Guarente at MIT identified Sir2 in yeast as an NAD+-dependent enzyme linking metabolic status to gene silencing and lifespan regulation. David Sinclair and colleagues at Harvard subsequently extended this work to mammalian systems, demonstrating that SIRT1 and other mammalian sirtuins regulate key processes including mitochondrial biogenesis, inflammatory responses, and DNA repair in an NAD+-dependent manner. These findings established NAD+ as more than a passive cofactor — it is an active regulator of cellular health.

NAD+ also serves as a substrate for poly(ADP-ribose) polymerases (PARPs), enzymes that play a central role in DNA damage detection and repair. When DNA strand breaks occur, PARPs consume NAD+ to synthesise poly(ADP-ribose) chains that recruit repair machinery to damage sites. Research has shown that heavy PARP activation under conditions of extensive DNA damage can substantially deplete cellular NAD+ pools, creating a competition for NAD+ between repair processes and other NAD+-dependent functions. The enzyme CD38, an NAD+ glycohydrolase, has been identified as another major consumer of NAD+ — work by Eduardo Chini’s group at the Mayo Clinic demonstrated that CD38 expression increases with age in multiple tissues and is a significant driver of age-related NAD+ decline.

The age-related decline in NAD+ levels is one of the most consistent findings in ageing research. Studies across rodent models and human tissues have documented progressive NAD+ depletion with advancing age, correlating with reduced sirtuin activity, impaired mitochondrial function, and increased susceptibility to metabolic stress. Research by Sinclair’s group demonstrated that restoring NAD+ levels in aged mice through precursor supplementation improved mitochondrial function, enhanced exercise capacity, and reversed certain molecular markers of ageing in skeletal muscle. These studies have generated significant interest in understanding whether NAD+ decline is a cause or consequence of ageing — and whether it represents a modifiable factor.

The comparison between direct NAD+ and its biosynthetic precursors — nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) — is an active area of investigation. NMN and NR enter cells through specific transporters and are converted to NAD+ through the salvage pathway, with NMN requiring only a single enzymatic step (catalysed by NMNAT enzymes) while NR requires phosphorylation by nicotinamide riboside kinases (NRKs) before conversion. Direct NAD+ has historically been considered too large to cross cell membranes efficiently, but recent research has challenged this assumption. Studies have identified potential NAD+ transport mechanisms, and in cell-free and in vitro systems, direct NAD+ remains the preferred form for enzyme activity assays, reconstituted metabolic pathway studies, and any application where biosynthetic conversion would introduce unwanted variables.

NAD+ biosynthesis operates through three main routes: the de novo synthesis pathway from tryptophan (via the kynurenine pathway), the Preiss-Handler pathway from nicotinic acid, and the salvage pathway that recycles nicotinamide back to NAD+ via NAMPT and NMNAT enzymes. Research into these pathways has revealed tissue-specific differences in their relative contributions and has identified NAMPT — the rate-limiting enzyme in the salvage pathway — as a key regulatory node. Studies in rodent models have shown that NAMPT expression declines with age in several tissues, providing a mechanistic link between ageing and reduced NAD+ synthesis capacity.

Beyond energy metabolism and DNA repair, NAD+ research has expanded into circadian biology, neurodegeneration, and immune function. Work by Joseph Bass and colleagues demonstrated that NAD+ oscillations driven by NAMPT expression are integral to circadian clock function, with disrupted NAD+ cycling associated with metabolic dysfunction in animal models. In neuroscience, research has explored NAD+ depletion as a factor in axonal degeneration, with the SARM1 enzyme identified as an NAD+-cleaving executioner in injured neurons. These diverse research threads underscore NAD+’s position as a molecule of truly cross-disciplinary significance. All findings referenced pertain to in vitro and animal model research; this product is supplied strictly for research use only.