Vitamin C provides antioxidant benefits, which are important to protect the skin from free radicals and environmental aggressors
Retinol: GHK-Cu can be used with Retinol, and many find they work synergistically

Nutritional Information Lamb meal, peas, chickpeas, lentils, sweet potatoes, powdered cellulose, potatoes, chicken fat (preserved with mixed tocopherols), flaxseed, natural flavor, ocean fish meal, menhaden fish oil (preserved with mixed tocopherols), DL-methionine, choline chloride, taurine, dried chicory root, L-Carnitine, glucosamine hydrochloride, kale, chia seed, pumpkin, blueberries, oranges, quinoa, dried kelp, coconut, spinach, carrots, papaya, yucca schidigera extract, dried Lactobacillus plantarum fermentation product, dried Bacillus subtilis fermentation product, dried Lactobacillus acidophilus fermentation product, dried Enterococcus faecium fermentation product, dried Bififidobacterium animalis fermentation product, vitamin E supplement, chondroitin sulfate, iron proteinate, zinc proteinate, copper proteinate, ferrous sulfate, zinc sulfate, copper sulfate, potassium iodide, thiamine mononitrate (vitamin B1), manganese proteinate, manganous oxide, ascorbic acid, vitamin A supplement, biotin, niacin, calcium pantothenate, manganese sulfate, sodium selenite, pyridoxine hydrochloride (vitamin B6), vitamin B12 supplement, riboflflavin (vitamin B2), vitamin D3 supplement, folic acid

Methods Enzymol 252:3853 Ulusu NN, Tandogan B (2007) Purification and kinetic properties of glutathione reductase from bovine liver