Healthspan.

Spermidine: promising in animals, unproven in people

Evidence grade: Emerging. Strong animal data and supportive observational studies, but a 12-month randomized human trial missed its primary outcome. No human data on aging or lifespan. See how we grade.

What spermidine is

Spermidine is a natural polyamine found in cells and in food. A 2009 study in Nature Cell Biology reported that its concentration inside cells declines during human aging, and that it triggers autophagy, the process cells use to clear out damaged parts [1]. Autophagy is the main reason spermidine gets attention in longevity circles.

The animal evidence

The animal data are the strongest part. Spermidine extended the lifespan of yeast, flies and worms, and of human immune cells in the lab, and it reduced oxidative stress in aging mice. Enhanced autophagy was crucial for these effects [1]. In a 2016 study in Nature Medicine, oral spermidine extended lifespan in mice and protected the heart in old mice. In rats prone to salt-driven high blood pressure, it lowered blood pressure and delayed progression to heart failure. Spermidine did not protect the heart in mice whose heart cells lacked Atg5, a protein needed for autophagy. That supports autophagy as the mechanism [2].

Human data: diet studies

In people, most data come from diet questionnaires. The same 2016 paper found that higher dietary spermidine was linked to lower blood pressure and a lower rate of cardiovascular disease [2]. In the Bruneck study, 829 adults aged 45 to 84 were followed from 1995 to 2015. Higher spermidine intake was associated with lower all-cause mortality, even after adjusting for lifestyle and other dietary factors. The finding was replicated in a second cohort. The authors estimated the mortality difference between the top and bottom thirds of intake was similar to that of being about 5.7 years younger [3].

These studies show association, not cause. People who eat more spermidine-rich foods may differ in other ways that also matter.

Human data: supplement trials

A pilot trial in 30 older adults with subjective cognitive decline tested a spermidine-rich plant extract for three months. Memory performance was moderately better than placebo [4]. The follow-up was larger and longer. The SmartAge trial randomized 100 adults aged 60 to 90 with subjective cognitive decline to a wheat-germ extract providing 0.9 mg of spermidine per day, or placebo, for 12 months. There was no significant change in memory, the primary outcome, or in secondary outcomes. Exploratory analyses hinted at effects on inflammation and verbal memory, which the authors said need testing at higher doses [5].

So the larger, longer trial did not confirm the pilot result. We found no trial testing spermidine on aging or lifespan in people.

Safety and regulation

In SmartAge, adverse events were balanced between the spermidine and placebo groups [5]. In Great Britain, spermidine-rich wheat germ extract is authorised as a novel food for food supplements for adults, excluding pregnant and breastfeeding women, up to the equivalent of 6 mg of spermidine per day [6]. That is a regulatory ceiling, not a recommended dose.

If you take medication or have a medical condition, talk to a doctor before adding a supplement.

Should you take it?

On current evidence, spermidine is a reasonable thing to be curious about and an unreasonable thing to expect much from. The habits in our foundations protocol and sleep protocol rest on far more human evidence.

If you decide to try a supplement, this is a product we can link to. We have not verified the manufacturer's health claims, and they go beyond the evidence above:

These are affiliate links. If you buy through them, we earn a commission, and you don't pay more.

Frequently asked questions

What does spermidine do?

Spermidine is a natural polyamine that triggers autophagy, the process cells use to clear damaged components. In yeast, flies, worms and mice it extended lifespan. Those effects have not been shown in people.

Does spermidine extend lifespan in humans?

There is no trial showing that. Observational diet studies link higher spermidine intake to lower mortality, but those studies cannot prove cause and effect.

Does spermidine improve memory?

A small 3-month pilot trial suggested a benefit, but the larger 12-month SmartAge trial found no significant effect on memory compared with placebo.

Is spermidine safe?

In the 12-month SmartAge trial, adverse events were balanced between the spermidine and placebo groups. In Great Britain it is authorised for adult food supplements up to 6 mg of spermidine per day, excluding pregnant and breastfeeding women. Talk to a doctor if you take medication.

Can I get spermidine from food?

Yes. Spermidine is found in food, and the human mortality data come from diet questionnaires, not supplements.

Sources

  1. Induction of autophagy by spermidine promotes longevity. Nature Cell Biology, 2009. https://pubmed.ncbi.nlm.nih.gov/19801973/
  2. Cardioprotection and lifespan extension by the natural polyamine spermidine. Nature Medicine, 2016. https://pubmed.ncbi.nlm.nih.gov/27841876/
  3. Higher spermidine intake is linked to lower mortality: a prospective population-based study. The American Journal of Clinical Nutrition, 2018. https://pubmed.ncbi.nlm.nih.gov/29955838/
  4. The effect of spermidine on memory performance in older adults at risk for dementia: A randomized controlled trial. Cortex, 2018. https://pubmed.ncbi.nlm.nih.gov/30388439/
  5. Effects of Spermidine Supplementation on Cognition and Biomarkers in Older Adults With Subjective Cognitive Decline: A Randomized Clinical Trial. JAMA Network Open, 2022. https://pubmed.ncbi.nlm.nih.gov/35616942/
  6. Authorised Regulated Food and Feed Products for Great Britain: Spermidine-rich wheat germ extract (NOVEL-130). Food Standards Agency (UK), 2025. Page last updated 1 April 2025. https://data.food.gov.uk/regulated-products/novel_authorisations/novel-130