Spermidine

What is spermidine and what does it do in the body?

Spermidine is a small, positively charged molecule counted among the natural polyamines together with spermine and putrescine; it is widely found in cells and organisms. Eisenberg and colleagues report that the intracellular concentration of spermidine declines during human aging. ^[7] This “decline” is a measurement; it does not mean that deficiency causes disease or that correcting it with a supplement provides benefit. Spermidine has not been defined as an essential nutrient like a vitamin or mineral; therefore there is no daily requirement or deficiency threshold.

The review by Madeo and colleagues in Science relays that spermidine has protective effects on the heart and nervous system in rodent models and works dependent on functional autophagy; Madeo and colleagues also relay that spermidine preserves mitochondrial function and shows anti-inflammatory properties; the review says that dietary polyamine intake in human epidemiological studies is associated with reduced cardiovascular and cancer-related death, and states that, because spermidine is already present in the daily diet, clinical studies increasing intake appear feasible. ^[8]

Does spermidine provide longevity?

The 2009 study by Eisenberg and colleagues reported that spermidine administration markedly extended the lifespan of yeast, flies, and worms and of human immune cells (in culture); in aging mice, it was seen to suppress oxidative stress. The study argues that the lifespan extension is linked to autophagy. ^[7] This study does not report lifespan extension in mice; the results are in simple organisms and cells in culture. A longevity effect is not an outcome that has been measured in humans; the evidence grade is E (not studied in humans).

The review by Madeo and colleagues says that, because spermidine is already present in human nutrition, clinical studies increasing intake appear feasible; that is, this 2018 review discusses studies to be planned, not a lifespan outcome in humans. ^[8]

Does spermidine protect memory and cognition?

12-month study (SmartAge). The phase 2b study by Schwarz and colleagues in JAMA Network Open is a single-center, double-masked, placebo-controlled RCT conducted in Germany. One hundred participants aged 60–90 with subjective cognitive decline (51 spermidine, 49 placebo; mean age 69; 49% women) received, for 12 months, a spermidine-rich supplement obtained from wheat germ (0.9 mg/day of spermidine) or a microcrystalline cellulose placebo; 89% of participants completed the study. The between-group difference in the primary outcome, mnemonic discrimination performance, was −0.03 (95% CI −0.11 to 0.05; p = 0.47); there was no significant change in secondary outcomes either. Exploratory analyses indicated a possible benefit for verbal memory and inflammation, and the authors wrote that these need confirmation in higher-dose studies. Adverse events were balanced between groups. ^[1] Among the limitations, the authors list that amyloid status was known in only 30% of participants, so there may be many people without amyloid or tau pathology, and that 12 months may have been too short to see change in cognition. ^[1]

Funding and conflict-of-interest statement: the study was supported by the German Federal Ministry of Education and Research; a company also provided funding for developing the extract, and some of the authors reported shareholding and consulting relationships with this company, and one author reported being the company’s managing director during the study; it was stated that the funders had no role in design, analysis, and publication. ^[1]

3-month pilot. In the pilot study by Wirth and colleagues, 30 people aged 60–80 who were cognitively intact but had subjective cognitive decline received a spermidine-rich plant extract or placebo for 3 months. Memory performance was moderately better in the group comparison (contrast mean 0.17; 95% CI −0.01 to 0.35; Cohen d 0.77), and mnemonic discrimination ability improved in the spermidine group (mean difference −0.11; 95% CI −0.19 to −0.03) and did not improve in the placebo group. ^[2] The confidence interval of the contrast mean includes zero; the sample is small, and the authors state that a 12-month follow-up study is needed. In the 12-month phase 2b study described above, the primary outcome was not significant.

Is spermidine from food associated with death and cancer risk?

The Bruneck study by Kiechl and colleagues is a prospective community cohort that followed 829 people aged 45–84 between 1995 and 2015; diet was assessed by dietitian-administered food frequency questionnaires repeated in 1995, 2000, 2005, and 2010, and 341 deaths were observed. As the tertiles of spermidine intake rose, the all-cause mortality rate fell from 40.5 to 23.7 and to 15.1 per 1,000 person-years. The HR adjusted for lifestyle and other factors was 0.76 per 1 SD higher intake (95% CI 0.67–0.86); the association was independently confirmed in the SAPHIR study in Salzburg (HR adjusted for age, sex, and caloric ratio 0.71; 95% CI 0.53–0.95). The difference between the upper and lower tertiles corresponded to being 5.7 years younger. ^[4] Two commentary articles are registered on PubMed for this paper. An observational association does not show dietary spermidine as a separate factor; a diet rich in spermidine may also reflect a different dietary pattern overall.

The Takayama study in Japan followed 13,355 men and 15,724 women aged 35 and older for 16 years (2,901 deaths in men, 2,438 in women); intake was mostly estimated using polyamine databases of Japanese foods. After adjustments, no polyamine’s intake was significantly associated with all-cause or cause-specific death; in women, a finding suggestive of a positive association (“suggestive”) between spermidine intake and cancer death was seen between the highest and lowest quartiles, with HR 1.38 (95% CI 0.99–1.93; trend p = 0.02). The authors write that their results do not support the view that dietary spermidine has a beneficial effect on mortality. ^[5] The lower limit of the confidence interval is below 1; the direction is toward an increase, but it is not definitive.

The Women’s Health Initiative observational study by Vargas and colleagues reported, in 87,602 postmenopausal women, that total dietary polyamine intake was not positively associated with colorectal cancer; the HRs in quintiles 2–5 versus the lowest quintile were 0.82 (0.68–1.00), 0.81 (0.66–0.99), 0.91 (0.74–1.12), and 0.80 (0.62–1.02); the decreased risk was not significant in all quintiles, and there was no significant association with cancer-related death either. ^[6] These data measure intake through diet; they do not measure supplement doses.

Does the supplement raise blood spermidine levels?

In the randomized, placebo-controlled, triple-blind, two-arm crossover study by Senekowitsch and colleagues, 12 healthy volunteers took 15 mg/day of spermidine in two 5-day periods (9-day washout). Compared with placebo, plasma spermine rose, spermidine and putrescine levels did not change, and there was no polyamine change in saliva. The authors suggest that spermidine is converted to spermine in the intestine and that effects may partly come from spermine; the authors state as their own interpretation that doses below 15 mg/day are unlikely to show short-term effects. The study received no external funding and declared no conflict of interest. ^[9]

In the study by Keohane and colleagues, 37 healthy men aged 50–70 were followed for 7 and 28 days with high-purity spermidine trihydrochloride (40 mg/day) or placebo. No significant change from placebo was seen in clinical, lipid, biochemistry, and hematology parameters, no product-related side effects were reported, and there was no marked change in serum and urine polyamine concentrations. ^[10] Two authors of the study are employees of the company that makes the product, and the other authors received funding from the company. The abstract does not state whether the 40 mg is the weight of the trihydrochloride salt or elemental spermidine; for this reason, it cannot be assumed to be in the same unit as the “spermidine equivalent” limit in Türkiye.

Is spermidine safe?

In the safety study by Schwarz and colleagues, the mouse toxicity study showed no illness, behavioral change, or increase in tumorigenic or fibrotic events at 28 days of repeated dosing. In the human part, in 30 people with subjective cognitive decline (aged 60–80), a plant extract containing 1.2 mg/day of spermidine was compared with placebo for 3 months: there was no difference in vital signs, weight, clinical biochemistry, hematology, and self-reported health, and adherence was above 85%. ^[3] The financial interests of four of the authors in the company developing the extract were declared. ^[3]

Overall picture: human data are short-term (high dose up to 28 days, low dose up to 12 months), small, and in mostly older or healthy volunteers; they are linked to manufacturers. For pregnancy and breastfeeding, the Türkiye list requires a “not to be used” label warning (below). Biologically, polyamines are needed for both normal and cancer cell growth; Vargas and colleagues relay this information as a rationale in the introduction of their study. ^[6] This is a mechanistic hypothesis and does not mean that the supplement increases or decreases cancer risk; the signal in the Takayama cohort does not show cause and effect either.

What is the regulatory status in Türkiye?

In Türkiye, spermidine appears in the Ministry of Agriculture and Forestry’s food supplement legislation under the name “spermidine-rich extract of wheat germ”; it is not a drug. In the September 21, 2026 version of the Ministry’s Restricted Substances List, the following conditions are written for this substance: it must comply with Annex-1 of the Turkish Food Codex Novel Foods Regulation; the label must carry the warning “Hamile ve emzirenler tarafından kullanılmamalıdır.” (should not be used by pregnant and breastfeeding women); the spermidine-rich extract of wheat germ and spermidine are declared as the active substance. The upper limit is the amount equivalent to 6 mg/day of spermidine and is written for ages 18 and older excluding pregnant and breastfeeding women; the publication date is May 5, 2025 and the update date is July 3, 2026. ^[11]

This limit is defined in different units and for a different purpose from the doses used in studies, 0.9 mg/day (12 months, extract), 15 mg/day (5 days), and 40 mg/day (up to 28 days, pure spermidine); the comparison is not a recommendation. This guide does not recommend products or places of supply.

Evidence table: claim, population, and limits

This guide does not recommend individual doses; the numbers above relay study results.