NAD⁺ salvage
NAD+ is not mostly made from scratch; it is recycled, and this enzyme is the bottleneck in the recycling. That matters because it is also the one place in the whole NAD+ picture where there is real human evidence. Measured on muscle biopsies, NAMPT abundance falls with age — and twelve weeks of aerobic or resistance training raised it again in both young and older people.
In depth
The rate-limiting enzyme of the salvage pathway. It converts nicotinamide back into NMN so it can become NAD+ again — which is how most tissues keep their supply, since nicotinamide is what every NAD-consuming enzyme leaves behind.
What drives it
Training load increases it.
Twelve weeks of aerobic and resistance exercise training reversed the age-dependent decline in NAD+ salvage capacity in human skeletal muscle, raising NAMPT abundance. This is the most direct human intervention evidence anywhere in the NAD+ map, and it is exercise rather than a supplement. PMC6577427 — Aerobic and resistance exercise training reverses age-dependent decline in NAD+ salvage capacity in human skeletal muscle. PMC6577427
What it drives
It increases Cellular fuel.
The TAP. NAMPT catalyzes the rate-limiting step of the salvage pathway, converting nicotinamide to NMN, which the NMNATs then convert to NAD+. Most mammalian tissues depend on this route because NAM is itself the product of every NAD-consuming enzyme. The one piece of human evidence in this whole node set: NAMPT abundance in human skeletal muscle correlates negatively with AGE, and 12 weeks of aerobic or resistance exercise training raises it. Measured on muscle biopsies in young and older people. PMC6577427 — Aerobic and resistance exercise training reverses age-dependent decline in NAD+ salvage capacity in human skeletal muscle ; Chini 2024, Aging Cell, doi 10.1111/acel.13920 / PMC10776128 — NAD metabolism: role in senescence regulation and aging. doi 10.1111/acel.13920 · PMC6577427
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.