In plain language
Follistatin 344 is a precursor isoform of follistatin that is processed in the body, including to the shorter cell-binding form. Like other follistatins it inhibits myostatin and activins to allow muscle growth. Evidence is largely preclinical and gene-therapy based, and injectable follistatin 344 peptide lacks human trials.
What it is explored for
Follistatin 344 is the precursor isoform that appears often in follistatin gene-therapy research, which keeps it in the spotlight for muscle science. The evidence is still early and mostly preclinical, with no human trials of the administered peptide, so its benefits are a research question rather than a settled fact. Here is where interest is concentrated.
- Muscle growth and lean mass
- Myostatin and activin research
- Gene-therapy muscle research
- Strength and performance interest
- Body-composition research
These are areas of active interest and reported use, not proven outcomes. This peptide carries a preliminary evidence rating, see the evidence summary below for how strong the science actually is.
How it works
Follistatin 344 is a precursor isoform that can be processed, including to the shorter FST-288 form that binds cell surfaces, and it inhibits myostatin and activins in the TGF-beta family.
- Myostatin and activin binding. Neutralizes myostatin and activins, factors that normally restrain muscle growth.
- Precursor processing. It can be cleaved to shorter forms, including the cell-surface-binding FST-288 isoform.
- Gene-therapy context. Follistatin 344 sequences are among those used in follistatin gene-therapy research for muscle.
Its behavior is characterized mainly in biochemical, animal, and gene-therapy studies. There are no human trials of administered follistatin 344 peptide.
Evidence summary
Evidence for follistatin 344 is preliminary. The follistatin and myostatin field shows strong animal effects, and follistatin 344 sequences appear in gene-therapy research, but there are no controlled human trials of administered follistatin 344 peptide for muscle or other outcomes. Benefit and safety in people are not established.
Reported safety & side effects
Human safety data for administered follistatin 344 is lacking. As a broad inhibitor of TGF-beta family signaling, theoretical concerns extend beyond muscle to other tissues and reproduction. Long-term effects in people are unknown.
Frequently asked
Is follistatin 344 FDA-approved?
No. Follistatin 344 is not approved by the FDA for any use. It is sold as a research chemical, and follistatin gene therapy remains investigational.
How is follistatin 344 different from follistatin 315?
They are different splice isoforms. Follistatin 344 is a precursor that can be processed to shorter cell-binding forms and acts more locally, while follistatin 315 is the freely circulating serum form with lower cell-surface affinity.
Is there human evidence for muscle growth?
No. The data is biochemical, animal, and gene-therapy based. There are no controlled human trials of administered follistatin 344 peptide, so muscle benefit and safety in people are not established.