Spermidine is a natural compound in many foods that switches on autophagy, your cells' recycling system. In mice, it extended lifespan and protected the heart. In an Italian population study, people who ate the most spermidine had a lower risk of dying during follow-up, but that kind of study can't prove cause. The first 12-month human trial of a spermidine supplement found no improvement in memory. Eating spermidine-rich whole foods is reasonable; supplements are unproven.
- SymptomWorn-out cells and stiffening heart with age
- Before thatDamaged parts aren't cleared
- Before thatThe cell's recycling system slows
- RootAutophagy declines with age
What spermidine is
Spermidine is a small molecule found in every living cell, including yours. It belongs to a family called polyamines. You get it from your diet, your gut bacteria make some, and your cells produce it, though levels in some tissues seem to fall with age.
Its claim to fame: it switches on autophagy, the recycling system that clears out your cells' broken parts. That's the same process fasting is thought to boost, which is why spermidine gets called "autophagy from your plate".
The promising animal data
In a 2016 study, mice given spermidine in their drinking water lived longer, even when they started late in life, and had healthier, less stiff hearts. When the researchers blocked autophagy, the heart benefits disappeared, which suggests the recycling system is how spermidine works.[1] That's grade C evidence: real, but in mice.
What we know in people
Diet and survival in northern Italy
B · ObservationalIn 829 adults followed for about 20 years, those who ate more spermidine had a lower risk of dying during follow-up, even after accounting for other lifestyle factors.[2] But this was an observational study, which watches what people do rather than testing a treatment, and people who eat more spermidine also tend to eat more whole grains, beans and vegetables, so this can't prove spermidine itself was responsible.
Spermidine supplements are proven to extend life by boosting autophagy.
Proven in mice. In humans, a promising link with diet, and a 12-month trial that found no memory benefit.
Food first: where to find it
| Food | Spermidine level |
|---|---|
| Wheat germ | Very high |
| Soybeans, natto | High |
| Aged cheese (e.g. cheddar, parmesan) | Moderate to high |
| Mushrooms | Moderate |
| Peas, lentils, beans | Moderate |
| Whole grains | Moderate |
Conveniently, these are foods with plenty of other health benefits, so eating more of them is a low-risk bet whatever spermidine itself turns out to do.
The bottom line
Spermidine is one of the more scientifically interesting longevity molecules because it acts on a real upstream process, cellular recycling, and works in mice. In humans, the evidence is a promising dietary link and one disappointing supplement trial. Eat the foods; hold off on expensive supplements until better trials arrive. For the bigger picture on cell recycling, read how long you have to fast for autophagy.
Frequently asked questions
What foods are highest in spermidine?
Wheat germ is the richest common source. Others include soybeans and natto, aged cheeses, mushrooms, legumes such as peas and lentils, and whole grains.
Do spermidine supplements work?
In mice, spermidine extended life. In humans, the only long trial so far, in older adults with memory complaints, found no improvement in memory after 12 months, though doses were low. Better human trials are needed.
Is spermidine safe?
Spermidine from food is part of a normal diet. Supplements at studied doses were well tolerated in trials. Talk to your doctor before using them, especially if you have cancer or are being treated for it, since spermidine affects cell growth processes.
Does spermidine trigger autophagy like fasting?
In cells and animals, yes, it activates autophagy, which is why it's sometimes called a fasting mimetic. Whether food or supplement doses do this meaningfully in humans hasn't been shown.
Sources
- Eisenberg T, et al. Cardioprotection and lifespan extension by the natural polyamine spermidine. Nature Medicine, 2016.
- Kiechl S, et al. Higher spermidine intake is linked to lower mortality: a prospective population-based study. American Journal of Clinical Nutrition, 2018.
- Schwarz C, et al. Effects of spermidine supplementation on cognition and biomarkers in older adults with subjective cognitive decline: a randomized clinical trial. JAMA Network Open, 2022.