Follistatin vs Thymulin

A detailed comparison to help you understand the differences and choose the right peptide for your research goals.

Follistatin

Follistatin is a glycoprotein that inhibits myostatin, the protein responsible for limiting muscle growth. By blocking myostatin, follistatin can theoretically allow for increased muscle development beyond natural limits.

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Thymulin

Thymulin (Facteur Thymique Sérique) is a zinc-dependent nonapeptide hormone produced by thymic epithelial cells. It plays important roles in T-cell differentiation and immune system maturation.

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Side-by-Side Comparison

AspectFollistatinThymulin
MechanismBinds to and neutralizes myostatin and activin, both of which are negative regulators of muscle mass. This removes the natural brake on muscle growth, allowing for enhanced hypertrophy.Requires zinc for biological activity. Promotes T-cell differentiation, modulates cytokine production, and influences neuroendocrine function. Levels decline significantly with age.
Typical DosageResearch protocols typically use 100-300mcg daily, though optimal dosing is not well established. Gene therapy approaches have also been studied.Research protocols vary. Often studied alongside zinc supplementation. Typical research doses in the microgram range.
AdministrationSubcutaneous injection. Different isoforms exist (FS344, FS315) with varying properties. Requires careful sourcing due to complexity.Subcutaneous or intramuscular injection in research settings. Requires adequate zinc status for activity.
Side EffectsLimited human data. Theoretical concerns about effects on other organs where activin signaling is important.Limited data on exogenous administration. Theoretical effects on immune function require monitoring.
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Key Differences

Unique to Follistatin:

Unique to Thymulin:

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