L-Glutathione exists in the body in 2 forms that recycle back and forth, a reduced (or "active") form and an oxidized form
One study found that the seminal plasma copper concentration had a positive effect on sperm parameters, including volume and motility (130)
Safety, Stability, and Storage This copper peptide has a favorable safety profile across decades of research
The copper content of GHK-Cu formulations has been a theoretical safety consideration, given that excessive copper can be toxic - however, the amounts used in cosmetic and research applications are extremely small, the copper is tightly chelated by the peptide (reducing free copper availability), and topical absorption of copper from these products appears minimal and well below levels that would cause systemic copper accumulation or toxicity
According to a study by the Journal of Applied Physiology, BPC-157 has been shown to promote tendon healing
Some experts suggest NAC might be more consistent at boosting intracellular glutathione than valid oral glutathione supplements (WebMD