Follistatin 315 vs Humanin
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Anti-Aging & Longevity
Humanin- 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.
- Humanin is a mitochondria-derived peptide (MDP) encoded in the 16S rRNA region of the mitochondrial genome. It protects neurons and other cells from apoptosis, improves insulin sensitivity, and declines significantly with age. HNG (S14G-Humanin) is a synthetic analog with 1000x greater potency.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- ~4–8 hours (HNG)
- Admin Route
- SubQ, IM
- SubQ
- Research
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- Typical Dose
- No established human dosing protocol
- 2–8 mg
- Frequency
- Research use only
- 3–5 times 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
- Neuroprotection against amyloid-beta toxicity (Alzheimer's relevance)
- Inhibits cellular apoptosis
- Improves insulin sensitivity
- Reduces cardiovascular risk markers
- Anti-inflammatory effects
- Correlates with longevity in centenarian studies
- Protects against ischemic injury
- Potential cancer cell apoptosis sensitization
- 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 irritation
- Limited human safety data available
- Stacks With
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