Comparison
Spermidine vs Thymosin Alpha-1
Side-by-side of Spermidine and Thymosin Alpha-1. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Spermidine
Spermidine supplement benefits cover autophagy induction, longevity signals, and cognition. Wheat germ extract data, doses, and human trials reviewed.
Thymosin Alpha-1
Thymosin alpha-1 peptide (Zadaxin, thymalfasin): 28-amino-acid TA1 immunomodulator. Dosing, T-cell effects, hepatitis B and HCV adjunct evidence.
Effects at a glance
Spermidine
- •Endogenous polyamine that induces autophagy via EP300 acetyltransferase inhibition and TFEB activation
- •Concentrated in wheat germ, soybeans, aged cheese, and mushrooms; ~10 to 15 mg/day in Mediterranean diets
- •Eisenberg 2016 reported dietary spermidine extended mouse lifespan and improved cardiac function
- •Wirth 2018 pilot (n=28) reported cognitive signal at 0.9 mg/day in older adults at risk for dementia
- •Larger Wirth 2019 follow-up (n=85) did not replicate the memory benefit at 12 months
- •Generally regarded as safe at supplemental doses; food-source position is reassuring
Thymosin Alpha-1
- •28-amino-acid synthetic peptide identical to thymic-derived immunomodulator
- •Approved in over 35 countries as Zadaxin for hepatitis B, hepatitis C adjunct, and immune support
- •Not FDA approved in US; compounded by 503A/503B pharmacies for off-label immune support
- •Modulates T-cell maturation, NK activity, and Th1 polarization in immunocompromised states
- •Standard label dose: 1.6 mg subcutaneously twice weekly
- •Cleanest safety profile in the peptide class with hundreds of regulated trials behind it
Side-by-side
| Attribute | Spermidine | Thymosin Alpha-1 |
|---|---|---|
| Category | supplement | peptide |
| Also known as | spermidine trihydrochloride, wheat-germ-extract spermidine | Talpha1, Ta1, Zadaxin, Thymalfasin |
| Half-life (hr) ↗ | 6 | 2 |
| Typical dose (mg) ↗ | 1.2 | 1.6 |
| Dosing frequency | daily, typically morning with food | 2x weekly |
| Routes | oral | subcutaneous, intramuscular |
| Onset (hr) | 2 | 24 |
| Peak (hr) | 4 | 168 |
| Molecular weight | 145.25 | 3108.32 |
| Molecular formula | C7H19N3 | C129H215N33O55 |
| Mechanism | Induces macroautophagy via inhibition of EP300 histone acetyltransferase and activation of TFEB-mediated lysosomal biogenesis. Substrate for hypusination of eIF5A, required for translation of mitochondrial respiration proteins. | Synthetic peptide modulator of innate and adaptive immunity. Promotes T-cell maturation and CD4/CD8 production, modulates Th1/Th2 balance, stimulates NK cell activity, and modulates TLR2/TLR9 signaling in dendritic cells. |
| Legal status | OTC dietary supplement (wheat-germ extract has GRAS status in US) | Approved in 35+ countries as Zadaxin (hepatitis B, hepatitis C adjunct, immune support); not FDA approved in US; compounded by 503A/503B pharmacies for off-label use; not on WADA Prohibited List |
| WADA status | allowed | unknown |
| DEA / Rx | OTC supplement (not scheduled) | Rx only via international approval or US compounding (no controlled-substance schedule) |
| Pregnancy | Insufficient data; not routinely recommended at supplemental doses | Not recommended; insufficient data |
| CAS | 124-20-9 | 62304-98-7 |
| PubChem CID | 1102 | 16130571 |
| Wikidata | Q411089 | Q913854 |
Safety profile
Spermidine
Common side effects
- mild GI upset (rare)
- headache (rare)
Contraindications
- wheat-germ allergy or celiac disease (for wheat-germ-extract products)
- active cancer (theoretical)
- pregnancy and lactation (insufficient data)
Interactions
- DFMO (difluoromethylornithine): competing polyamine metabolism; do not combine without oncology guidance(moderate)
Thymosin Alpha-1
Common side effects
- mild injection-site irritation (rare)
- transient mild fatigue (rare)
- occasional headache (rare)
Contraindications
- pregnancy
- lactation
- active organ transplant rejection therapy
- systemic immunosuppression for autoimmune disease (relative)
- severe active autoimmune disease (caution)
Interactions
- interferon-alpha: additive immune effect; used clinically in approved combination protocols(minor)
- calcineurin inhibitors (cyclosporine, tacrolimus): theoretical destabilization of immunosuppression; avoid(major)
- antimetabolites (azathioprine, mycophenolate): theoretical destabilization of immunosuppression; avoid(major)
- vaccine administration: may augment vaccine response in elderly or immunocompromised; coordinate with clinician(minor)
Which Should You Take?
Spermidine comes out ahead for most readers on the criteria we weight: 2 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-A outcome catalogued. Thymosin Alpha-1 is the right call when one of the conditionals below applies.
- → If your priority is healthspan extension, pick Spermidine.
- → If your priority is focus or working memory, pick Spermidine.
- → If your priority is immune support, pick Thymosin Alpha-1.
- → If your priority is post-training recovery, pick Thymosin Alpha-1.
Edge case: If you want to avoid Approved in 35+ countries as Zadaxin (hepatitis B, hepatitis C adjunct, immune support); not FDA approved in US; compounded by 503A/503B pharmacies for off-label use; not on WADA Prohibited List, Spermidine is the more accessible choice.
Default choice: Spermidine. Lower friction to source, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Thymosin Alpha-1 only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Spermidine and Thymosin Alpha-1?
Spermidine and Thymosin Alpha-1 differ in category (supplement vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Spermidine or Thymosin Alpha-1?
Spermidine half-life is 6 hours; Thymosin Alpha-1 half-life is 2 hours.
Can you stack Spermidine with Thymosin Alpha-1?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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