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They contain about 100x higher levels of sulforaphane than mature broccoli

Pickart and Margolina's 2018 review in the International Journal of Molecular Sciences catalogues the wider picture, including clinical work in which a GHK-Cu facial cream applied over 12 weeks improved skin density, firmness, and the look of fine lines, and GHK-Cu is one disclosure-worthy case, which is covered in the disclosures section below

(PubMed) Vinceti M, Crespi CM, Malagoli C, Del Giovane C, Krogh V

Collagen is essential for maintaining skin elasticity and firmness, giving your complexion a smoother and more youthful appearance

This is one of the few studies using human cells, but it is an in vitro model, not a clinical outcome