Longevity Dietary supplement

Spermidine

Spermidine HCl

Evidence: Studied in humans. Example dose: finalize with a provider. Not a fact-check stamp.

1mg – 1-2 mg Oral Daily

Spermidine is a naturally occurring polyamine (chemical name: N-(3-aminopropyl)butane-1,4-diamine) synthesized endogenously in nearly all human cells and obtained dietarily from foods such as wheat germ, aged cheese, soybeans, mushrooms, mature fermented foods, and natto. Discovered in human seminal fluid in the late 1600s by Antonie van Leeuwenhoek (hence the name 'spermine' family), spermidine is now recognized as a master regulator of cellular autophagy - the housekeeping process by which cells clear damaged proteins and organelles.

Quick Start

Route

Oral

Start low

1mg Oral

Frequency

Daily

Timing

Anytime

Take with breakfast or lunch. Most clinical trial protocols use 1-2mg/day from wheat germ extract or synthetic. No fasting required, but autophagy effects synergize with intermittent fasting / time-restricted eating windows.

❋

Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first

Conservative start

1mg · Oral · Daily

conservative starter

1mg

Daily

Standard

Autophagy Induction

1-2 mg · Oral · Daily

human clinical trial · Schwarz et al. 2022 (JAMA Netw Open); NCT03094546; PMID 35616942

THE DEFINITIVE TRIAL WAS NEGATIVE. SmartAge randomised 100 adults for 12 months and found no significant change in the primary memory endpoint (difference -0.03, 95% CI -0.11 to 0.05, P=.47) or in any secondary outcome. An earlier smaller pilot was positive, which is how the optimistic claims spread. Separately, 15 mg/day for 5 days did not measurably raise circulating spermidine, so oral absorption is itself in question.

1-2 mg

Daily

◆

How it works

Spermidine's primary mechanism is direct activation of cellular autophagy through inhibition of the histone acetyltransferase EP300 (also called p300/CBP). EP300 normally acetylates autophagy-related proteins to keep autophagy suppressed; spermidine binding to EP300 reduces this inhibition, derepressing autophagy gene expression via TFEB (transcription factor EB), the master regulator of lysosomal biogenesis and autophagy. The autophagy induction is dose-dependent, conserved across yeast, worms, flies, mice, and humans, and is the proposed mechanism for spermidine's lifespan extension in model organisms.

Beyond autophagy, spermidine modulates histone H3 acetylation patterns, leading to broad transcriptional changes in genes regulating cellular stress resistance, metabolism, and longevity. Spermidine also supports mitochondrial respiration efficiency, increases mitophagy (selective clearance of damaged mitochondria), and stabilizes RNA structure through polyamine-RNA interactions. In immune cells, spermidine promotes a shift toward anti-inflammatory phenotypes and supports T-cell function with age.

Cardiovascular effects involve restoration of titin elasticity in cardiomyocytes (improving diastolic function), reduction of cardiac hypertrophy, improvement of endothelial function via increased nitric oxide signaling, and reduction of arterial stiffness. In the brain, spermidine crosses the blood-brain barrier (limited but present) and supports memory consolidation, synaptic plasticity, and clearance of protein aggregates implicated in Alzheimer's and Parkinson's disease.

What to expect

Early

Days 1–7

Weeks 1-2: subclinical autophagy induction. No subjective change.

Evidence

HumanModerate

AnimalPresent

In-vitroPresent

Each reference below was re-fetched from its PubMed record, and the quoted sentence was confirmed to appear in that abstract and to support the claim it sits under. Follow any of them to read the source.

One hundred participants were randomly assigned (1:1 ratio) to 12 months of dietary supplementation with either a spermidine-rich dietary supplement extracted from wheat germ (0.9 mg spermidine/d) or placebo (microcrystalline cellulose).

One hundred participants were randomly assigned (1:1 ratio) to 12 months of dietary supplementation with either a spermidine-rich dietary supplement extracted from wheat germ (0.9 mg spermidine/d) or placebo (microcrystalline cellulose).

Effects of Spermidine Supplementation on Cognition and Biomarkers in Older Adults With Subjective Cognitive Decline: A Randomized Clinical Trial. JAMA network open · 2022 · PMID 35616942

Evidence scope. Randomized trial in older adults with subjective cognitive decline; wheat-germ dietary supplement at 0.9 mg/day for 12 months, closely matching but not exactly the card's 1 mg amount.

Claims we could not support

No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.

Complete regimen: 1mg via Oral, Daily. The verified row supports only the narrower dose/route boundary stated above, not every element of the displayed regimen.

Mechanism: Spermidine's primary mechanism is direct activation of cellular autophagy through inhibition of the histone acetyltransferase EP300 (also called p300/CBP). EP300 normally acetylates autophagy-related proteins to keep aut. No checked live abstract supported this full mechanistic claim at the card's formulation/route without extrapolation.

Primary safety claim: Generally very well tolerated at standard doses (1-2mg/day). No checked live abstract directly established this as the primary concern for the card's exact formulation and regimen.

Interactions & stacking

Two different questions: what is documented about running these together, and what is documented about drawing them into the same syringe. A good pharmacological partner can still have to be pinned separately.

Documented together

NMN / NRDifferent mechanism (NAD+ replenishment via NMN/NR vs autophagy via spermidine). Compatible without expected conflicts; some practitioners stack both for broad longevity support.

Omega-3 Fatty AcidsAnti-inflammatory effects complement spermidine's anti-inflammatory profile. No known interactions.

ResveratrolBoth activate autophagy through complementary mechanisms (spermidine via EP300, resveratrol via SIRT1). Synergistic autophagy induction in preclinical models.

RapamycinBoth are autophagy inducers (rapamycin via mTOR inhibition, spermidine via EP300). Theoretical synergy though high-dose rapamycin makes spermidine somewhat redundant.

Keep separate

DFMO (eflornithine)DFMO inhibits ornithine decarboxylase, blocking endogenous polyamine synthesis. Counterproductive to spermidine supplementation goals (though clinically rare combination - DFMO is used in cancer chemoprevention/treatment).

Antibiotics (gut-modulating)Theoretical interaction: gut bacteria contribute to polyamine pool. Broad-spectrum antibiotics may transiently reduce gut-derived spermidine. Not a clinical concern, but timing supplementation away from antibiotic courses is reasonable.

Check any specific pair in the Stack & Interaction Checker, which answers both questions separately. Absence of a documented conflict is not evidence of safety.

Pharmacokinetics

Illustrative plasma concentration · 26 h

Half-life

~6 hours

Systemic plasma

Peak · Tmax

~1-2 hours

Oral

Elimination

~24-36 hours

Parent compound and metabolites

Bioavailability

Moderate (~30-40% oral) - intestinal absorption supplemented by gut bacterial production. Tissue uptake mediated by polyamine transporters.

Duration of action

Autophagy induction effects accumulate with daily dosing; cellular benefits sustained for hours to days post-dose. Long-term effects (cardiovascular, cognitive) require continuous intake.

Clearance

Hepatic and tissue metabolism via spermidine N1-acetyltransferase (SAT1) and polyamine oxidase pathways. Renal excretion of metabolites and conjugates.

Storage. Store at room temperature (20-25C) in a cool, dry place. Wheat germ extract capsules are shelf-stable for 18-24 months. Synthetic spermidine trihydrochloride is stable for 2+ years. Protect from moisture and light.

Regulatory status

Classified as a dietary supplement in the US (not FDA-approved for any medical condition). Available over the counter. Generally Recognized as Safe (GRAS) status not formally established for synthetic spermidine; wheat germ extract has long history of dietary use. EU has authorized spermidine-rich wheat germ extract as a novel food ingredient.

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The guide & community

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