Why raising NAD+ is not enough - the SIRT1 reserve problem

Lifespan.io · Article

A review in Biology argues that many NAD+ and SIRT1 therapies have disappointed because trials measure the wrong thing: how much NAD+ or SIRT1 is present, rather than whether SIRT1 can still respond under stress. The authors propose SIRT1 functional reserve - the remaining capacity of SIRT1-dependent processes to engage, coordinate and recover when a cell is challenged - as the metric that actually matters.

Key takeaways:

• Presence is not function: NAD+ sits in separate pools inside the cell, SIRT1 accumulates in less active forms with age, and a high total reading can hide low usable activity where it is needed
• Context changes the reading: the same SIRT1 level can produce different output depending on cell type, stress history and what else in the regulatory network has become the limiting factor
• The framework is a proposal, not a validated test: the authors set out experiments to measure reserve directly, and linking it to real functional outcomes in people remains the open translational question

Hype check: Proven - the compartment and isoform problems are documented in the literature the review synthesises. Promising - functional reserve as a measurable, trial-ready metric; it still needs experimental validation. Marketing - any claim that a supplement raising NAD+ levels has therefore restored youthful SIRT1 function; that inference is exactly what this review rejects.