BPC-157 has a reputation that runs well ahead of its evidence base. It is worth separating what has actually been measured from what gets repeated on forums.
What it is
BPC-157 is a synthetic fragment of a protein found in human gastric juice. The sequence is stable in stomach acid, which is unusual for a peptide and is the reason it was first investigated for gut conditions rather than for tendons.
Where the evidence is strongest
The gut work is the oldest and most consistent. Animal models have repeatedly shown protection of the gastric lining and accelerated healing of induced ulcers and fistulas.
The tendon and ligament work is more recent and is what drives most of the athletic interest. In rat models, BPC-157 increased tendon fibroblast outgrowth, cell survival and migration, with faster recovery of function after transection.
Almost all of the musculoskeletal evidence is preclinical. There are no large randomised human trials.
Where it runs out
This is the part usually skipped. The overwhelming majority of BPC-157 studies are in rats, at doses that do not translate cleanly to human use. Human data is limited to small, mostly uncontrolled reports. Anyone telling you the human dosing is settled is guessing.
The practical read
The mechanistic case is genuinely interesting and the safety signal in animal work has been mild. But "promising in rodents" is not the same as "proven in people", and the honest position is that BPC-157 sits in the experimental column.