NAD+: Cellular Energy, Sirtuins, and Longevity Research Guide

Nicotinamide adenine dinucleotide (NAD+) is a dinucleotide coenzyme found in all living cells. It exists in two interconvertible forms: the oxidised NAD+ and reduced NADH. The NAD+/NADH ratio is a fundamental indicator of cellular redox state and metabolic activity.

Beyond its classical role as a redox carrier in glycolysis, the TCA cycle, and oxidative phosphorylation, NAD+ is a substrate for three classes of enzymes central to cellular regulation:

• Sirtuins (SIRT1-7) — NAD+-dependent deacetylases/deacylases regulating gene expression, metabolism, and stress responses
• PARPs — poly(ADP-ribose) polymerases consuming NAD+ to facilitate DNA strand break repair
• CD38/CD157 — NAD+ glycohydrolases involved in calcium signalling and immune cell function

NAD+ levels decline with age in multiple tissues, a finding that has generated substantial research interest in NAD+ replenishment as a strategy for studying and potentially counteracting age-related metabolic decline.

Sirtuins are often described as longevity regulators due to their roles in genome stability, mitochondrial biogenesis (SIRT1/SIRT3), inflammation suppression (SIRT1), and caloric restriction response pathways. SIRT1 and SIRT3 are the most studied in the context of metabolic disease and ageing.

The central importance of NAD+ to sirtuin function means that NAD+ availability directly governs sirtuin activity. Studies using NAD+ or precursor supplementation to elevate cellular NAD+ levels have demonstrated downstream sirtuin activation — including increased mitochondrial biogenesis markers, improved insulin sensitivity, and reduced inflammatory cytokine expression in preclinical models.

Research-grade NAD+ is used as a direct substrate in enzymatic assays measuring SIRT1/SIRT3 activity, allowing researchers to characterise sirtuin kinetics and screen for modulators under controlled conditions.

PARP enzymes consume large quantities of NAD+ during DNA repair — a fact with significant implications for NAD+ homeostasis under conditions of genotoxic stress. Excessive PARP activation can deplete cellular NAD+ to levels insufficient for normal metabolism, contributing to cell death pathways in ischaemia, inflammation, and neurodegenerative contexts.

Research investigating the interplay between PARP activity and NAD+ availability is relevant to understanding DNA damage response, chemotherapy sensitisation, and the metabolic consequences of genome instability.

Three forms are commonly used in NAD+ research:

• NAD+ — the active coenzyme. Used for direct enzymatic assays, in vitro supplementation, and applications where precursor conversion cannot be assumed
• NMN (nicotinamide mononucleotide) — a precursor converted to NAD+ intracellularly via NMNAT enzymes. More stable than NAD+ in solution; widely used in systemic animal studies
• NR (nicotinamide riboside) — a precursor converted via NRK → NMN → NAD+. Higher oral bioavailability in some models; used extensively in human biomarker studies

Research-grade NAD+ is the appropriate choice for in vitro enzymatic studies, cell-free systems, and precision metabolic assays where the conversion assumptions inherent to precursor use are not appropriate.

RetaLABS NAD+ 100mg is supplied as a lyophilised powder with >98% purity. Store at −20°C in a desiccated environment — NAD+ is hygroscopic and degrades with moisture exposure. Reconstitute with sterile water or PBS; use promptly or aliquot at −20°C. Each batch is accompanied by a COA, available on request.