The DAC form (albumin-bound, ~5.88.1-day half-life) has the only human data
This is why knowing your concentration is not just helpful
Stimulates Collagen and Elastin Synthesis: GHK-Cu upregulates genes associated with collagen, elastin, and glycosaminoglycan production, improving skin firmness and extracellular matrix integrity 3
Javed R, Zia M, Naz S, Aisida SO, Ain Nu, Ao Q
G., Lamberti, A., Maffulli, N
The B12-IF complex is absorbed by cells in the final section of the small intestine (the ileum), where IF is cleaved from B12 and subsequently, B12 passes into the blood where transport proteins bind to it and is distributed to cells all around the body (Obeid et al., 2015