Spermidine extends lifespan in yeast, flies, worms, and multiple mouse models. A large European observational study found higher dietary spermidine associated with lower all-cause mortality. And it is found in wheat germ, soybeans, and aged cheese. Here's what the science shows.
Spermidine has one of the more curious names in longevity science — it was first isolated from human semen in 1678, hence the name — and one of the more consistent cross-species longevity records of any supplement currently available. Lifespan extension in yeast, fruit flies, nematodes, and mice. A large European epidemiological study linking higher dietary spermidine to lower all-cause mortality. A small randomized trial showing improvement in cognitive function in older adults with memory complaints.
This is not a supplement built on a single mechanistic hypothesis. The cross-species data is real and replicated. Here is what spermidine is, how it works, and what the human evidence shows.
Spermidine is a polyamine — a naturally occurring compound with multiple amine groups — that is produced by all living cells and found in particularly high concentrations in wheat germ, soybeans, aged cheese (particularly cheddar), mushrooms, green peas, and some fermented foods. Dietary polyamine intake has declined over the past century as Western diets have shifted away from traditionally fermented and aged foods.
Intracellular spermidine levels fall with age, mirroring the decline in cellular autophagy capacity. Whether the decline is cause or effect of aging is still debated, but the correlation is consistent across tissues and species.
Spermidine's primary longevity mechanism is autophagy induction. It inhibits EP300, an acetyltransferase that suppresses autophagy gene expression. When EP300 is inhibited, autophagy genes are de-repressed and autophagy activity increases. This is a different mechanism than the rapamycin pathway (which inhibits mTOR upstream) or urolithin A (which acts on PINK1-Parkin mitophagy specifically) — making spermidine potentially additive to both.