Follistatin 315 vs Thymagen
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Immune Support
Thymagen- 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.
- Thymagen is a dipeptide bioregulator (Glu-Asp) developed by Professor Vladimir Khavinson, tissue-specific for the thymus gland. It supports T-lymphocyte maturation, thymic function, and immune system normalization. As the thymus involutes with age (thymic atrophy), immune competence declines. Thymagen is used to support immune restoration, particularly in aging, post-illness recovery, and immunodeficiency states.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- Short (minutes); sustained gene-regulatory effects
- Admin Route
- SubQ, IM
- SubQ, Oral
- Research
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- Typical Dose
- No established human dosing protocol
- 10 mg per day
- Frequency
- Research use only
- Daily for 10–30 days
- 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
- Supports thymic epithelial cell function and T-cell maturation
- May partially restore thymic output reduced by age-related atrophy
- Normalizes T-lymphocyte subpopulation balance
- Supports immune recovery after illness, surgery, or chemotherapy
- Anti-aging effects on thymic tissue
- Complementary to Thymosin Alpha-1 and Thymalin in immune protocols
- May improve vaccine responsiveness in older individuals
- 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
- Generally well tolerated
- Mild injection site reactions
- No significant immunological adverse events reported
- Stacks With
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