What it is
NMN (nicotinamide mononucleotide) is a molecule cells convert into NAD+, a coenzyme central to energy metabolism and DNA repair that declines with age. Oral NMN is a popular supplement aimed at replenishing NAD+.
Why it matters for longevity
Because NAD+ supports sirtuins and mitochondrial function, raising it is an attractive idea, and in animals NAD+ precursors improve several age-related measures.
What the evidence shows
This is Experimental in humans. Small trials suggest NMN can raise NAD+ markers and showed a metabolic signal in one study (improved muscle insulin sensitivity in prediabetic women), but there is no evidence yet that it extends healthy human lifespan, and supplement quality varies widely.
What to ask a clinic
Ask what specific, measured outcome is expected, at what dose and from which product, and recognise that “raises NAD+” is a biomarker change — not a proven health outcome.