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 reconstitution calculator.
Doses shown are those reported in published research, not a recommendation.
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.
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.
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).
Contraindications
- pregnancy
- active malignancy
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
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.
References
- A phase 1/2a follistatin gene therapy trial for Becker muscular dystrophy · Mendell JR, et al. · 2015