The Hostynek and Maibach group at UCSF measured exactly this in 2011: human skin permeation of GHK-Cu as a function of skin layer, with the result that the peptide accumulates in the upper stratum corneum but does not pass through to viable epidermis or dermis in any meaningful quantity 4
J Neurosci 14(5 Pt 1):26972707 Melo IS, Santos YMO, Costa MA et al (2016) Inhibition of sodium glucose cotransporters following status epilepticus induced by intrahippocampal pilocarpine affects neurodegeneration process in hippocampus [J]

Over time, this supports steady, natural weight loss especially in stubborn areas like the belly GLP-1 PATHWAY SUPPORT: Formulated to support your natural GLP-1 pathway, the same hormone behind powerful weight-loss medicines, helping manage blood sugar levels and reduce hunger swings without injections or prescriptions CLINICALLY PROVEN INGREDIENTS: Contains Reducose and Berberine for GLP-1 support and slow carb absorption, Carnipure L-Carnitine to help burn stored fat, plus Apple Cider Vinegar and Chromium for better sugar balance and appetite control DIABETES CARE AND BLOOD SUGAR MANAGEMENT: Helps manage blood sugar levels by preventing post-meal sugar spikes, keeping your blood sugar steady throughout the day, and supporting better carbohydrate metabolism for Indians who enjoy traditional carb-rich foods CONVENIENT DAILY USE: Simply tear open one stick pack, mix with 200ml water, and drink before any meal

May Reduce Oxidative Stress What it is: Damage caused by free radicals to cells and tissues
[DOI] [PubMed] [Google Scholar] 81.Mar M., Cederbaum A.I