Spermidine: A Promising Autophagy Signal That Is Still Mostly Food and Mice

Summary

Spermidine is one of the cleanest longevity leads in the lab, an autophagy-inducing polyamine that reproducibly extends lifespan in yeast, flies, worms and mice, and higher dietary spermidine tracks with lower mortality across independent human cohorts, but the human outcome evidence for a supplement is essentially absent: the one notable interventional trial (SmartAge, on cognition) was null on its primary endpoint, the cohort signal is exactly what whole-food diets and healthy-user behaviour would produce anyway, and a capsule of wheat-germ extract is not the whole-food pattern it was derive