Yes, glutathione is legal to purchase in the United States when sold as an oral dietary supplement under FDA regulations governing DSHEA (Dietary Supplement Health and Education Act)
The World Anti-Doping Agency (WADA) and USADA classify BPC-157 as a prohibited substance under the S0: Non-Approved Substances category
Here is what researchers most often study, all in animal or cell models: Cytoprotection: Much of the early work looked at how the peptide affects the stomach and gut lining in rodents
See these diagrams: Source: Clinical Procedures for Safer Patient Care by Doyle & McCutcheon
Glutathione may have potential benefits for improving cellular health, strengthening the immune system, reducing oxidative stress, improving liver function, enhancing skin health, fighting infections, supporting healthy blood vessels, reducing muscle damage, and more
However, there is already evidence that Epithalon activates gene for this protein