A naturally occurring polyamine, studied for the same autophagy pathway that gives rapamycin its mechanistic case — with a much earlier-stage human evidence base.
Disabled macroautophagy is one of the twelve hallmarks of aging — and spermidine is one of the few compounds proposed to address it without touching mTOR directly.
Spermidine is a polyamine, naturally present in foods like wheat germ and aged cheese, studied for its autophagy-inducing properties through a mechanism distinct from rapamycin's direct mTORC1 inhibition. It is sold as a dietary supplement and is not FDA-approved for any indication. Its current human evidence comes primarily from Phase II work out of the Madeo lab, examining cognitive endpoints rather than hard mortality or morbidity outcomes.
Both compounds are studied as autophagy inducers, but through different routes: rapamycin acts by directly inhibiting mTORC1, the master suppressor of autophagy; spermidine acts through polyamine-related mechanisms that don't require mTOR inhibition at all. This distinction matters clinically — rapamycin's mTOR inhibition carries known immunosuppressive trade-offs from its transplant-medicine use; spermidine's pathway, at least mechanistically, doesn't carry that same baggage, though its human safety and efficacy data is considerably less mature.
Spermidine's safety profile in available human studies has been generally favorable, but "generally favorable in early studies" and "validated longevity intervention" are different claims. Geroevidence's profile remains under editorial review pending additional published human evidence — the same bar applied to every compound on the platform.