NAD⁺ metabolism: mitochondrial mechanism

Definition

Category: Cofactor / signalling pathway

Also known as: NAD+, nicotinamide adenine dinucleotide

NAD+ is a central redox cofactor for OXPHOS and the substrate for sirtuins and PARPs. Tissue NAD+ tends to fall with age, which is the rationale for the precursors nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). The downstream sirtuin/mTOR signalling biology overlaps the mtorix cluster and is cross-referenced there rather than duplicated here.

Key points

NR and NMN are NAD+ precursors, but the measured compartment matters. The included Martens2018 NR trial increasedPBMC NAD+; in the included NMN2023 trial, serum nicotinamide increased while serumNAD+ andNMN were below quantification. These findings are not equivalent to a demonstrated functional or lifespan benefit.
The NAD+/sirtuin longevity narrative is shared with mtorix.com — see mtorix for the sirtuin/mTOR pharmacology; mitoix keeps the mitochondrial-cofactor view.
Raising a NAD+ biomarker is not the same as a demonstrated human healthy-aging outcome.

Related interventions

Sourcing

Standard NAD+ metabolism reviews (Verdin; Rajman et al.). NAD+/sirtuin pharmacology cross-referenced to mtorix.com.

Reference synthesis (mechanism context, not a human-trial evidence tier).