Follistatin 315 vs LL-37
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Immune SupportRecovery & Repair
LL-37- Summary
- Follistatin 315 is a splice variant isoform of follistatin produced by alternative mRNA processing. Unlike Follistatin 344 which is tethered to cell surfaces via heparan sulfate proteoglycans, FST-315 circulates freely in the bloodstream and has broader systemic distribution. It is the predominant circulating form and exerts systemic myostatin inhibition as well as FSH suppression, making it relevant to both muscle growth and reproductive endocrinology.
- LL-37 is the only known human cathelicidin antimicrobial peptide. It kills bacteria, fungi, and viruses by disrupting their membranes, while simultaneously modulating immune responses. Used for antimicrobial protection, immune priming, and wound healing.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- Very short (~1–2 hours) in plasma due to protease degradation; topical use bypasses systemic clearance
- Admin Route
- SubQ, IM
- SubQ, Topical, Intranasal
- Research
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- Typical Dose
- No established human dosing protocol
- 100–300 mcg
- Frequency
- Research use only
- 2–3x per week
- Key Benefits
- Systemic myostatin inhibition for whole-body muscle growth
- Freely circulating — broader tissue distribution than FST-344
- Strong FSH-suppressive activity useful in certain hormonal protocols
- Potential for greater anabolic effect across multiple muscle groups simultaneously
- May be more relevant to reproductive endocrinology applications
- Studied in gene therapy approaches for muscular dystrophy
- Broad-spectrum antimicrobial (bacteria, fungi, viruses)
- Promotes wound healing and angiogenesis
- Immune system modulation — enhances innate immunity
- Reduces LPS-mediated endotoxemia
- Anti-biofilm activity against resistant organisms
- Promotes tissue regeneration and keratinocyte migration
- May protect against sepsis
- Side Effects
- Systemic FSH suppression — significant concern for fertility
- Greater potential for off-target effects vs FST-344 due to systemic distribution
- Limited human safety data
- Potential cardiac hypertrophy with prolonged high-dose exposure
- Injection site redness and irritation
- Mild inflammatory response at injection site
- Potential pro-inflammatory at high doses
- Rare: fever or flu-like symptoms at initiation
- Stacks With
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