Long-term NMN helped aging mice preserve metabolic and physical function

Oral NMN was rapidly used to synthesize NAD+ in tissues. Over the year, treated mice showed less age-associated body weight gain, better energy metabolism, improved insulin sensitivity, healthier lipid profiles, higher physical activity, and protection against several declines in eye function. Skeletal muscle and other tissues also showed molecular patterns consistent with improved mitochondrial oxidative metabolism. Importantly, the authors did not report obvious toxicity or major adverse effects during the long intervention. The study did not show that NMN extended lifespan; it showed that a central metabolic cofactor could be replenished and that multiple healthspan-like readouts moved in a favorable direction. Because the intervention ran across a large fraction of the mouse lifespan, the result was harder to dismiss as a short metabolic spike after dosing.