NAD+ Precursors (NMN)New

Nicotinamide mononucleotide—direct NAD+ precursor showing promise for cellular energy, DNA repair, and aging reversal in preclinical studies. EVIDENCE UPDATE (September 20, 2026): Peer-reviewed, and it concerns MONITORING rather than efficacy. Nature Metabolism 2026;8:1282-1290 (Tretowicz, Schomakers et al.; Houtkooper lab, Amsterdam UMC) quantified NAD+ across seven independent human cohorts using a rigorously validated UHPLC-high-resolution MS method designed to account for real-world analytical variability, and found whole-blood NAD+ STABLE with chronological age and UNCHANGED by lifestyle interventions, while responding as expected to nicotinamide riboside supplementation. The authors conclude blood NAD+ is not a useful biomarker of ageing or lifestyle, and that much of the age-related decline in the prior literature is plausibly assay variability. Scope: this does not refute tissue or intracellular NAD+ decline, does not test NMN specifically, and evaluates no clinical outcome of precursor supplementation - the preclinical NMN rationale is untouched. What it removes is the use of a blood NAD+ level as a biological-age readout, as evidence a patient "needs" NMN, or as proof a product is working; a supplement-induced rise confirms absorption, not benefit. Counterweight: GeroScience 2026 (Itabashi Longitudinal Study on Aging, 16 Sept 2026) found lower median whole-blood NAD+ in the 32 of 529 community-dwelling adults aged 65+ (6.0%) meeting revised J-CHS frailty criteria, surviving adjustment for age, sex and fasting time plus spline, Firth penalised-likelihood and haematological sensitivity analyses - the clearest human association to date between circulating NAD+ and a functional outcome, though cross-sectional, small in the frail subgroup, untested for reverse causation, and involving no supplement. Human NMN evidence remains short-duration surrogate endpoints.