Follistatin 315 vs TB-500
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Recovery & Repair
TB-500- 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.
- TB-500 is a synthetic fragment of Thymosin Beta-4, a naturally occurring peptide found in nearly all human and animal cells. It promotes cell migration to injury sites, accelerates tissue regeneration, and reduces chronic inflammation.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- 2–3 hours
- Admin Route
- SubQ, IM
- SubQ, IM
- Research
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- Typical Dose
- No established human dosing protocol
- 2–2.5 mg
- Frequency
- Research use only
- Twice weekly
- 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
- Enhances muscle tissue regeneration
- Accelerates healing of wounds and injuries
- Reduces inflammation and pain
- Improves flexibility and mobility
- Promotes new blood vessel formation
- Supports hair growth and skin health
- May improve cardiac function after injury
- Systemic healing effect — works at distance from injection site
- 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 discomfort
- Fatigue (rare)
- Headache (rare)
- Stacks With
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