What is spermidine?
Spermidine is a natural compound found in every living cell and in foods like wheat germ, soybeans and aged cheese, that switches on autophagy, the cell's recycling system.
If autophagy is your cells' garbage collection, spermidine is like a reminder note telling the garbage trucks to come out and do their rounds.
Why it matters for aging
Spermidine belongs to a family of molecules called polyamines, which help cells grow, divide and stay stable. Your cells make it, your gut bacteria produce some, and you get the rest from food. Levels in some tissues seem to fall with age.
Because it triggers autophagy, it's sometimes called a "fasting mimetic", a compound that imitates some effects of fasting. The best food sources are wheat germ, soybeans and natto, aged cheese, mushrooms, legumes and whole grains.
A common myth
Spermidine supplements are proven to extend human life.
Spermidine extended life in mice, and people who eat more of it tend to live longer, but that link can't prove cause. A 12-month human trial found no improvement in memory.
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Updated Nov 9, 2026 · All terms