In yeast, nicotinamide riboside helps extend life and turn off certain genes, but only if it boosts NAD+ levels using two specific recycling systems in the cell.

What we've found so far is that in yeast, the anti-aging effects of nicotinamide riboside appear to depend on its ability to increase NAD+ levels through specific cellular recycling pathways [1]. Our analysis of the available research shows this effect only occurs when two particular systems—Nrk1 and Urh1/Pnp1/Meu1—are functional and actively involved in processing nicotinamide riboside [1]. The evidence we've reviewed suggests that nicotinamide riboside can extend lifespan in yeast and influence gene activity linked to aging, but only when these specific pathways are present and able to produce NAD+ [1]. Without them, the benefits are not observed, indicating that NAD+ production through these routes is a key factor in the process [1]. This means the cellular machinery responsible for recycling nicotinamide riboside into NAD+ must be working for any anti-aging effects to occur [1]. So far, all the evidence we’ve analyzed supports this idea, with no studies indicating otherwise [1]. However, the total number of assertions we’ve reviewed is limited, and our understanding may change as more research becomes available. We are cautious about drawing firm conclusions because the current evidence base is narrow, even though it points in a consistent direction. In everyday terms: if someone were thinking about how nicotinamide riboside might affect aging at the cellular level, the current evidence suggests it only works in yeast when specific recycling systems are active and producing NAD+. We don’t yet know how this translates beyond yeast, but it highlights the importance of these pathways in the process.