Isoform of follistatin, a natural protein that blocks myostatin, the brake on muscle growth. Tested as gene therapy in muscular dystrophies; the "peptide" that is sold has no human studies.
Regulatory status
In clinical trials
Family
Myostatin and activin inhibitor protein (follistatin isoform)
Scientific evidence
Low
Number of findings
1
Where it acts
Bones and muscles
Also known as
follistatin-344, FS344, FST-344
Regulatory status
FDA (US): Not approved
EMA (EU): Not approved
Dose
There is no established dose in humans.
Safety
The gene therapy showed no adverse effects in 6 patients. The commercial injectable product has no safety data or purity guarantees; because it affects activin, it may interfere with reproductive hormones. Its use only makes sense in research or under medical supervision; buying it is not recommended.
Differences between women and men
The only human trial was done in men with Becker dystrophy (an X-linked disease). Follistatin takes part naturally in the regulation of FSH. View the study →
Effect by goal · level of evidence
Walking in Becker muscular dystrophy (gene therapy)
improvesLowclinical trial (A)in people
+29 a +125 m
6 patients received the FS344 gene in the quadriceps: 4 improved on the 6-minute walk test (+29 to +125 m) and biopsies showed less fibrosis.
Binds to myostatin and activin and keeps them from acting. Without that brake, muscle can grow and regenerate better. Follistatin also naturally regulates FSH, a reproductive hormone.
What the evidence says
In people
Walking in Becker muscular dystrophy (gene therapy). 6 patients received the FS344 gene in the quadriceps: 4 improved on the 6-minute walk test (+29 to +125 m) and biopsies showed less fibrosis. PubMed 25322757