Supplement evidence

046 / 575Experimental longevity

Spermidine

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The short answer

Early observational and small intervention studies examine cognition and aging biomarkers.

Evidence and scope: Emerging evidence
This status does not grade the ingredient for every goal, outcome, or person.
Important limitation: No adequate trial has shown extension of healthy human lifespan.
Before deciding: Long-term dose, product quality, and safety are not well established.

01 / PRACTICAL GUIDE

Dose, absorption, and combinations

These are indication-specific reference or studied ranges—not a personalized prescription. Start with the objective, then check the form, label, medicines, and health conditions.

Reference range by objective

Cognitive-performance researchAbout 0.9–6 mg/day supplemental spermidine in early trials

Reference or studied range—not a personalized prescription. The product label or a clinician may specify a different dose.

Dose source ↗

More is not automatically better. A clinician or product label may specify a different amount.

Absorption / solubilityWater-soluble

Water-soluble or readily water-dispersible. This does not mean excess is always harmless.

How it is commonly taken

Take consistently; food-derived and supplemental exposure differ.

Do not combine casually

No established therapeutic dose; pregnancy, cancer treatment, and long-term safety require clinician review.

Dose and use source ↗

Dose and use links lead to primary or official source material. Search links are discovery tools, not proof that every returned paper applies.

02 / EVIDENCE

What the research says

We keep supportive, mixed, negative, safety, and contextual findings together. The headline never replaces the underlying papers.

4research papers in this ledger

2unique primary studies represented

200unique participants represented

These are audited counts for this JIVANA collection, not search-result totals. Participants are counted once when multiple papers use the same cohort; review papers are not added again to participant totals.

Open the research timelineResearch timeline

Entries are ordered by publication year. A study period appears only when the source reports it.

2024

Evidence contextPMID 39594533

Human Supplementation with AM3, Spermidine, and Hesperidin

The combination changed several biomarkers and an Immunity Clock estimate. It cannot isolate spermidine, and an algorithmic age change is not evidence of longer life or fewer clinical events.

Published: 2024Duration: 2 monthsn=41 participants

Study design and methods

Design: Randomized placebo-controlled trial
Population: 41 adults aged 30–63
Intervention: AM3 150 mg, spermidine 0.6 mg, and hesperidin 50 mg twice daily versus placebo
Outcome: Immune, oxidative, inflammatory, and algorithmic biological-age biomarkers

Funding or conflict note: Excluded from totals because the three-ingredient intervention cannot identify a spermidine effect.

Open research record ↗

2022

Does not support the tested claimPMID 35616942 · NCT03094546

Effects of Spermidine Supplementation on Cognition and Biomarkers in Older Adults With Subjective Cognitive Decline

Spermidine did not improve the primary memory outcome or secondary outcomes. Exploratory verbal-memory and inflammation signals require validation and should not be presented as proven cognitive or anti-aging benefit.

Published: 2022Duration: 12 monthsn=100 participants

Study design and methods

Design: Randomized, double-masked, placebo-controlled phase 2b trial
Population: 100 adults aged 60–90 with subjective cognitive decline
Intervention: Wheat-germ extract providing spermidine 0.9 mg/day or placebo
Outcome: Mnemonic discrimination, other cognition and behavior, biomarkers, and safety

Open research record ↗

2018

Mixed or qualifiedPMID 30388439 · NCT02755246

The effect of spermidine on memory performance in older adults at risk for dementia

The small pilot suggested a memory effect, but the confidence interval included little or no benefit and the larger 12-month follow-up trial was null.

Published: 2018Duration: 3 monthsn=30 participants

Study design and methods

Design: Randomized, double-blind, placebo-controlled phase 2a pilot trial
Population: 30 cognitively intact adults aged 60–80 with subjective cognitive decline
Intervention: Spermidine-rich plant extract or placebo
Outcome: Mnemonic discrimination and memory performance

Funding or conflict note: Displayed as preliminary context and excluded from aggregate totals because the later SmartAge trial is the more definitive cohort-level evidence.

Open research record ↗

2017

Mixed or qualifiedPMID 29214104

A spermidine-based nutritional supplement prolongs the anagen phase of hair follicles in humans

The product increased anagen-phase follicles and related biomarkers. The study was preliminary, used a spermidine-based product, and did not establish patient-important outcomes for a diagnosed hair-loss condition.

Published: 2017Duration: 3 months, with a pull test at 6 monthsn=100 participants

Study design and methods

Design: Randomized, double-blind, placebo-controlled trial
Population: 100 healthy adults
Intervention: A spermidine-based nutritional supplement or placebo
Outcome: Hair-follicle growth phase, proliferation and apoptosis markers, and pull test

Funding or conflict note: Two authors were Giuliani employees, one was a consultant, and another received company travel support.

Open research record ↗

Unscreened discovery appendix—not evidence72 candidate publicationsSearch run: Aug 21, 2026

Complete for the displayed PubMed query at the search timestamp—not for all databases or every possible synonym. Candidates can be irrelevant, duplicate the same study, or report negative findings. They are never summed as evidence or participants until screened.

03 / SOURCES

Start with the source material

Official evidence overviewPubMed human-evidence index Live PubMed discovery searchNational Library of Medicine

The live search is for discovery only. Search-result counts change and are not included in the audited totals above.

Recent PubMed discovery recordsDirect links to the first 12 records returned by the reproducible search. These are discovery candidates—not reviewed summaries or a count of supportive findings.

04 / EXPERT CONTEXT

Expert context—not evidence

Expert positions are dated context—not scientific evidence. They never raise the evidence status or become consensus by repetition.

No direct, source-verified endorsement is currently recorded. Research authorship or discussion alone is not treated as endorsement.