Spermidine dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Spermidine is a natural compound in foods like wheat germ and aged cheese that helps cells clean house. A year-long memory study found no benefit. One diet study linked it to fewer deaths, and a bigger one did not.
Evidence grade for Spermidine: Moderate. The rule: at least one finished study in people, and at least 100 people who took it. The sum on this page: 2 completed trials, 130 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 130
- Human studies
- 2
- Found nothing
- 0
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
2 completed trials, 130 people given it
4 effects reported, 2 unwanted, 2 wanted, by people using it, not a trial
Goal pages: Brain, memory and mood, Ageing and longevity
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Spermidine is a compound in wheat germ and aged cheese. It turns on the cell's clean up process. People take pills of it to think better and live longer. It is a supplement.
What people take it for
- A longer life, from diet studies.
- Better memory.
- A fasting like effect without fasting.
What studies in people showed
People first. The biggest trial is SmartAge. It put 100 older adults on 0.9 mg a day for 12 months. The main memory test did not change. The gap was minus 0.03. Before that, a small 30 person memory study looked promising. A town diet study found people who ate more of it died less often. That is watching, not a trial. A later Japanese diet study found no link with death once other facts were counted. Nobody has shown a pill of it makes a person live longer. In mice, spermidine made them live longer in a 2016 paper.
What people report
Reports, not study results
The good
- It is in food already, so a wheat germ habit is cheap.
- The pills are usually easy on the stomach.
The bad
- The dose in pills is tiny next to the animal work.
- People stack it with everything else, so nobody can tell what did what.
Where these come from: The trial and diet numbers are on this page. The stack habit is from longevity forums.
My bottom line
The mouse story is real. The human memory trial that was built to confirm the small first study missed. I would eat the food and skip the pill.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Spermidine has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Memory and thinking130 people · 2 studies
What people using it report
Real people telling you what happened to them. Nobody checked it, and the people who post are not a fair sample, so it cannot prove anything works. It is still the best guide on this page to what people actually do with Spermidine, what they expect, and what goes wrong. The full account, including the negative reports, is below.
Animal and lab work, not yet tested in people
Real results, but from animals or cells, not people. What works in a mouse often does not work the same way in a person. Nobody can patent this, so nobody would ever earn back the cost of a study in people. That is usually why there is none.
- Cell energy and mitochondria1 animal or lab study
- Living longer1 animal or lab study
33 of the 36 indexed goals have no study of any kind behind Spermidine
No study in people, animals or cells on this page reports a result for these. That does not prove Spermidine does nothing for them. It does mean anything you have heard about Spermidine and one of these did not come from a study cited here.
Show full evidence
What is Spermidine?
Spermidine is a natural compound in foods like wheat germ and aged cheese that helps cells clean house. A year-long memory study found no benefit. One diet study linked it to fewer deaths, and a bigger one did not.
Spermidine is found in foods such as wheat germ and aged cheese. It turns on autophagy, the cell's way of cleaning out old parts. In 100 older adults with memory worries, a year of 0.9 mg a day did no better than a dummy pill. A smaller three-month study in 30 people had looked hopeful. In one town, people who ate more spermidine were less likely to die during the study. But a much bigger study in Japan, of 13,355 men and 15,724 women over 16 years, found no link. In mice, spermidine helped them live longer and kept their hearts working. It is sold as a supplement. The case in cells is strong. Proof that it helps people live longer is not there yet.
How does Spermidine work?
It turns on autophagy by blocking certain enzymes called acetyltransferases. That helps cells clear out damaged parts linked to ageing.
What have studies in people found about Spermidine?
A year-long memory study missed. A small memory study looked hopeful. One diet study linked spermidine to fewer deaths, and a later, bigger one did not. No study has tested whether it helps people live longer.
- Takayama, Japan: 13,355 men and 15,724 women followed for 16 years. After other factors were counted, spermidine in the diet was not linked to death.
- SmartAge: 100 older adults took 0.9 mg a day or a dummy pill for 12 months. The main memory test did not change. The gap was minus 0.03, which is no real difference.
- Bruneck: people who ate more spermidine were less likely to die during the study, after other factors were counted. This tracked diet. Nobody was given a pill.
- Schwarz 2018: 30 older adults, three months. Memory scores leaned toward spermidine, by a medium amount. The study was too small to be sure.
What this does not tell you: Diet studies cannot pull spermidine apart from everything else on the plate. The one real test of memory used a low dose and missed the main thing it measured. Nobody has given people spermidine and tracked how long they live.
What do people who took Spermidine report?
This is what real people say happened to them, good and bad. Nobody measured it. A report cannot tell a real effect from the lift people get just from expecting it to work, from a diet or training change made at the same time, or from what was really in the vial. We still put it near the top. It is the next best thing to a study in people: what happens when real people use it, including what goes wrong.
- The dominant argument is about source rather than effect: whether to buy a wheat germ extract capsule or simply eat wheat germ. People work through the arithmetic openly, noting that a couple of tablespoons of wheat germ contain roughly as much as a supplement serving, and that the supplements deliver a fraction of a milligram to about a milligram per serving.
- The doses discussed are small, around a milligram a day, taken from the human study figures rather than from anything scaled up.
- Reports of no perceived benefit are explicit, including from someone who ate wheat germ consistently for a period and noticed nothing.
- Two explanations circulate for that, and they pull in opposite directions: that the body absorbs little of it from food, or that a supplement delivering half a milligram cannot be expected to do anything either. Neither is resolved.
- There is essentially no side effect discussion, and no accumulated account of harm. In a compound taken at food-level amounts that is unsurprising and should not be read as a safety finding.
- The overall character of this discussion is people reasoning about labels and milligrams rather than describing outcomes, which is the most accurate thing to say about it.
Sources: Supplements and retailer discussion threads on LongeCity, reached through site-restricted search extracts of the threads because the site itself would not load from this environment, September 2026. Nothing above is attributed to any specific post and no post is reproduced.
The evidence, in charts
Fig. 1a · how many people
15,854people, across 3 studies in people cited here
| Study | People | Share |
|---|---|---|
| British Journal of Nutrition 2024 | 15,724 | 99% |
| JAMA Network Open 2022 | 100 | 1% |
| Cortex 2018 | 30 | 0% |
One study holds 99% of these people, so the total rests more on one study than its size suggests. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. 1 more study in people gives no headcount and is not counted here. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
4 of 6 sources here are studies in people. The rest are not.
- Study in people · done in people467%
- Animal study · done in animals233%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 5 different years, 2009 to 2024, counted from the list of sources on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Supplement
- Molecule weight
- 145.2 Da
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
No amino acid sequence is on file for Spermidine, which is expected: a supplement is not built from amino acids.
The studies we cite
- Study in people2018Higher spermidine intake is linked to lower mortality: a prospective population-based study
Nobody was given anything in this study. Researchers followed a town's people for years, recorded what they ate, and found that those eating more spermidine were less likely to die during that time. The catch is the usual one with diet research. People who eat more of something differ in many other ways, and no amount of number crunching catches them all. A link is not a cause.
Bruneck cohort: hazard ratio for all-cause death 0.76 per 1 SD higher dietary spermidine after adjustment; observational.
- Study in people2018The effect of spermidine on memory performance in older adults at risk for dementia: a randomized controlled trial
A tiny memory study looked hopeful. 30 older adults who felt their memory was slipping took a spermidine plant extract, or a dummy pill, for three months. Memory scores leaned toward the extract, by a medium amount. The authors said a bigger study would have to confirm it. That bigger study is the next card.
Phase IIa pilot. 30 adults aged 60 to 80 with subjective cognitive decline, three months of a spermidine-rich plant extract or placebo. Memory performance contrast mean 0.17 (95% CI -0.01 to 0.35), Cohen's d 0.77. NCT02755246.
- Study in people2022Effects of spermidine supplementation on cognition and biomarkers in older adults with subjective cognitive decline: a randomized clinical trial
The bigger memory study missed. SmartAge put 100 older adults on 0.9 mg of spermidine a day, or a dummy pill, for 12 months. 89 finished. The main memory test did not change. The gap was minus 0.03. Side effects were the same in both groups. Side looks at word memory and swelling markers are not the result the study was built to test.
SmartAge. 100 adults, mean age 69, with subjective cognitive decline randomised to 0.9 mg/day spermidine or placebo for 12 months. Primary mnemonic discrimination difference -0.03 (95% CI -0.11 to 0.05, p = 0.47). Secondary outcomes also null. NCT03094546.
- Study in people2024Dietary polyamine intake and all-cause and cause-specific mortality in Japanese adults in the Takayama study
A second diet study did not repeat the Bruneck survival link. Researchers followed 13355 men and 15724 women in Japan for 16 years and estimated spermidine in the diet. After other facts were counted, intake was not linked to death. A diet link in one town is not a pill result, and here the link did not travel.
Takayama cohort. 13,355 men and 15,724 women, 16 years of follow-up. After covariate adjustment, estimated dietary spermidine was not associated with all-cause or cause-specific mortality.
- Animal study2009Induction of autophagy by spermidine promotes longevity
In yeast, flies and worms, spermidine made them live longer. In a dish, human immune cells lived longer too. It worked by turning on the cell's clean-up process.
Spermidine extended lifespan in yeast, flies, worms and human immune cells by inducing autophagy.
- Animal study2016Cardioprotection and lifespan extension by the natural polyamine spermidine
In mice, spermidine given by mouth made them live longer and kept their hearts working better. It did this by boosting clean-up inside heart cells.
Oral spermidine extended mouse lifespan and preserved cardiac function through enhanced cardiac autophagy and mitophagy.
Common questions
Has Spermidine been tested in people?
Yes. 130 people given it across 2 completed trials cited here, 0 of which found nothing. Spermidine is a natural compound in foods like wheat germ and aged cheese that helps cells clean house. A year-long memory study found no benefit. One diet study linked it to fewer deaths, and a bigger one did not.
What is the Spermidine dosage?
No human dose established. Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose. 2 completed trials, 130 people given it
Is Spermidine FDA-approved?
Sold as a supplement or as part of food; not an approved drug
Does spermidine extend lifespan in people?
Not proven. It turns on cell clean-up. One diet study linked it to fewer deaths, but that does not show it was the cause, and a bigger diet study found no link. The evidence in people is still early.
Latest reading on Spermidine
Blog posts about Spermidine, newest first.