Adverse effect · Follistatin 344

How common is safety in humans with Follistatin 344?

D
Grade D — no human evidenceNone for the protein · effect size: not measurable · adverse
Short answerNo human evidence. As of 10 September 2026, only none for the protein exist for Follistatin 344 for safety in humans. Follistatin also neutralises activin, which regulates reproduction, inflammation and the pituitary. Systemic blockade in humans has never been characterised. The gene-therapy trial reported no adverse effects in six people over a limited follow-up — in muscle-restricted delivery.

What the studies show

Follistatin also neutralises activin, which regulates reproduction, inflammation and the pituitary. Systemic blockade in humans has never been characterised. The gene-therapy trial reported no adverse effects in six people over a limited follow-up — in muscle-restricted delivery.

Animal studies, cell studies, or anecdotes only. This is where almost every viral peptide sits. Promising and proven are different words for a reason.

In context

Follistatin is a natural protein that binds and blocks myostatin, the signal that limits muscle growth; animals engineered to overexpress it become dramatically muscular. 'Follistatin 344' is the full-length form, sold as a lyophilised injectable for muscle. No human trial has ever tested injecting it. The only clinical data is a 2015 gene-therapy study in six men with Becker muscular dystrophy, in which a virus carrying the follistatin gene was injected into the thigh muscles — some walked further, some did not, and it is not the product being sold. It is prohibited in sport.

Follistatin 344 is not approved; research reagent. Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is Follistatin 344 proven to cause safety in humans?
No. There is no human evidence for it (None for the protein); the claim rests on animal or cell studies and LYO grades it D.
What studies are behind the grade?
Follistatin also neutralises activin, which regulates reproduction, inflammation and the pituitary. Systemic blockade in humans has never been characterised. The gene-therapy trial reported no adverse effects in six people over a limited follow-up — in muscle-restricted delivery.
Is Follistatin 344 approved for this?
No. Follistatin 344 is not approved; research reagent; it is not an approved medicine for any indication in the jurisdictions LYO covers.

Other outcomes for Follistatin 344

Written and maintained by LYO Research — how pages are written and checked. Reviewed 10 September 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →