Follistatin 315 vs PGPIPN
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Immune Support
PGPIPN- 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.
- PGPIPN is a bioactive hexapeptide (Pro-Gly-Pro-Ile-Pro-Asn) derived from beta-casein during enzymatic digestion. It exhibits anti-inflammatory properties via opioid receptor modulation and cytokine suppression, making it relevant for gut health, systemic inflammation, and as a component of casein-derived functional foods.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- Estimated 30-120 minutes (peptide degradation)
- Admin Route
- SubQ, IM
- Oral, Subcutaneous (research)
- Research
- —
- —
- Typical Dose
- No established human dosing protocol
- 200-500 mg per day
- Frequency
- Research use only
- Once or twice daily
- 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
- Anti-inflammatory effects via cytokine suppression
- Gut mucosal protection and intestinal barrier support
- Opioid receptor modulation for gut motility regulation
- Potential analgesic activity via central and peripheral opioid pathways
- Explored for inflammatory bowel conditions and gut dysbiosis
- Natural origin (food-derived) with favorable safety profile
- 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 very well-tolerated given food-derived origin
- Theoretical opioid-mediated constipation at high doses
- Rare milk protein allergy in casein-sensitive individuals
- Stacks With
- —
- —