P21 vs Follistatin
Side-by-side comparison of key properties, dosing, and research.
Cognitive EnhancementAnti-Aging & Longevity
P21Anabolic & IGF
Follistatin- Summary
- P21 is a synthetic peptide derived from CNTF (ciliary neurotrophic factor) that promotes hippocampal neurogenesis, enhances memory and spatial learning, and may reduce amyloid-beta pathology. It is used as a neurogenic and cognitive enhancer with potential anti-Alzheimer's applications.
- Follistatin is an endogenous glycoprotein that acts as a potent inhibitor of myostatin and activin, two proteins that limit muscle growth. By binding and neutralizing myostatin, follistatin removes the primary brake on skeletal muscle hypertrophy, enabling significant muscle growth beyond normal physiological limits. It is distinct from its isoforms Follistatin 315 and Follistatin 344 in tissue distribution and binding affinity.
- Half-Life
- Not well characterized; likely short, but neurogenic effects persist long after administration
- ~3–5 hours (endogenous form)
- Admin Route
- SubQ, Intranasal
- IM, SubQ
- Research
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- Typical Dose
- 100–500 mcg
- 50–100 mcg per injection site
- Frequency
- Once daily
- Every other day or 2–3x per week
- Key Benefits
- Promotes hippocampal neurogenesis
- Enhances spatial memory and learning
- Increases BDNF expression
- Reduces amyloid-beta plaque formation (animal models)
- Anti-tau pathology potential
- Cognitive enhancement without stimulant effects
- Potential therapeutic for Alzheimer's and cognitive aging
- Potent myostatin inhibition enabling supraphysiological muscle growth
- Increases skeletal muscle mass and fiber size
- May accelerate recovery from muscle injury
- Potential benefits in muscular dystrophy and sarcopenia
- Synergistic with IGF-1 and growth hormone in anabolic protocols
- Animal studies show dramatic increases in muscle mass
- Reduces muscle fibrosis in dystrophic models
- Side Effects
- Generally well tolerated in animal studies
- Limited human clinical data
- Injection site reactions
- Potential mild fatigue at initiation
- Potential for excessive muscle growth if doses are not controlled
- FSH suppression with implications for fertility in women
- Theoretical risk of cardiac hypertrophy with prolonged high-dose use
- Limited human safety data available
- +1 more
- Stacks With
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