Follistatin-344: Myostatin Blockade and a Product Problem
A myostatin-blocking peptide with real biology behind it, but the injectable product sold to researchers has essentially no human evidence of its own.
What is Follistatin-344?
Follistatin-344 is a peptide that binds and neutralizes myostatin, the protein that acts as the body's natural brake on muscle growth, blocking myostatin is the same biological logic behind naturally myostatin-deficient animals (and rare human cases) developing dramatically increased muscle mass. The biology is real, but the human evidence gap is unusually wide: the only human data supporting follistatin's muscle effects comes from a one-time gene-therapy trial in Becker muscular dystrophy patients, a virus delivering the follistatin gene directly into muscle, which is a completely different intervention from the injectable peptide sold by research vendors. That injectable product has no published human studies of its own at any dose.
Quick facts
- Class
- Myostatin-neutralizing peptide (FST-344 splice variant)
- Brand Names
- No trademarked brand, sold as a research compound
- Legal Status
- Not FDA-approved for human use, research use only (RUO). The injectable peptide has no published human studies of its own
- Category
- Performance / Muscle
- Storage
- Store the lyophilized vial refrigerated (2-8°C) or at -20°C, away from light. Once reconstituted, keep refrigerated at 2-8°C and use promptly.
Dosing at a glance
1mg vial + 2mL bacteriostatic water = 500mcg/mL. Run the numbers in the Follistatin-344 reconstitution calculator.
Store the lyophilized vial refrigerated (2-8°C) or at -20°C, away from light. Once reconstituted, keep refrigerated at 2-8°C and use promptly.
What the evidence supports
| Claim | Grade | Basis |
|---|---|---|
| Muscle Growth | Fgrade | Mendell 2015 (Mol Ther, n=6): gene therapy (viral follistatin gene delivery) improved a 6-min walk test in Becker muscular dystrophy, a different intervention entirely from the injectable peptide. |
Follistatin-344 Mechanism of Action
Blocking the Body's Brake on Muscle Growth
Follistatin-344 binds and neutralizes myostatin, a protein that normally restrains skeletal muscle growth by signaling through the activin receptor pathway. Animals and rare humans with naturally low myostatin activity show dramatically increased muscle mass, this real biology is the entire rationale behind follistatin as a muscle-growth research compound.
A Real Peptide, Unlike Steroidal Myostatin-Adjacent Compounds
Unlike steroidal compounds that claim myostatin-pathway effects as a side mechanism (e.g. YK-11), follistatin-344 acts directly and specifically on myostatin itself as its primary, dedicated mechanism, the most mechanistically 'clean' myostatin-inhibition approach among peptides sold in this space.
Follistatin-344 Dosage and Protocols
Research Protocol Range
Research-vendor products are commonly dosed at 100-300mcg subcutaneous once daily. Since the injectable peptide has no published human dose-finding study at all, this range reflects informal research-community convention only.
Follistatin-344 Side Effects and Safety
No Human Safety Data for the Injectable Peptide
Because the injectable peptide has never been studied in humans, there is no characterized human side-effect profile for this specific product. The gene-therapy trial (a different intervention) reported generally mild tolerability, but this doesn't transfer to the injectable peptide's safety profile. Active malignancy is treated as a precautionary contraindication given myostatin's broader role in cell growth regulation.
Contraindications
Reported contraindications: pregnancy, active malignancy.
Follistatin-344 Research Evidence
The Human Data Is From a Different Intervention Entirely
The only human evidence connecting follistatin to muscle improvement comes from Mendell et al. (2015, Molecular Therapy), a gene-therapy trial in 6 Becker muscular dystrophy patients, a virus delivering the follistatin *gene* directly into muscle tissue, a one-time genetic intervention. 4 of 6 patients walked farther on a 6-minute walk test. This is fundamentally different from injecting the follistatin *peptide* itself, which is what research vendors actually sell.
Regulatory and Legal Status
Follistatin-344 has no FDA-approved indication and is not approved for human consumption. It is sold exclusively as a research-grade compound (RUO), and, importantly, the injectable peptide product itself has no published human studies at any dose. This is one of the largest gaps between marketing claims and actual product-specific evidence among compounds in this catalog. Researchers and users should verify the legal status of follistatin-344 in their jurisdiction and weigh this evidence gap carefully.
Trials and reviews
- Mendell follistatin gene therapyMolecular Therapy2015
4 of 6 Becker MD patients walked farther on a 6-min walk test, gene therapy, not the injectable peptide
Follistatin-344 Stacking and Combinations
Sometimes Paired With GH Secretagogues
Follistatin-344 is sometimes combined with GH secretagogue blends like CJC-1295 (no-DAC) + Ipamorelin in research protocols targeting muscle growth through two separate pathways, myostatin inhibition plus GH/IGF-1 stimulation. No formal combination trial data exists.
Follistatin-344 Pharmacokinetics
Not Established for the Injectable Peptide
No human pharmacokinetic study, absorption, half-life, clearance, has been published for the injectable follistatin-344 peptide. The gene-therapy trial doesn't produce comparable PK data since it's a fundamentally different delivery mechanism (viral gene expression vs. direct peptide injection).
Legal status
Not FDA-approved for human use, research use only (RUO). The injectable peptide has no published human studies of its own
Regulatory standing is a statement about how a compound may be sold and prescribed, not about whether it works. See how we grade evidence.
Frequently asked questions
What is a typical Follistatin-344 dose?
Published research protocols report 100–300 mcg, 1x daily. This is the range described in the literature, not a recommendation.
What is the half-life of Follistatin-344?
Not established in humans for the injectable peptide form.
Is Follistatin-344 backed by strong evidence?
Follistatin-344 carries a REGEN research grade of F. REGEN Research Tier F, real mechanism, but the sold injectable peptide has no human evidence of its own.
How is Follistatin-344 administered?
Routes reported in the literature: subcutaneous.
Who should avoid Follistatin-344?
Contraindications noted in the literature include pregnancy, active malignancy.