acetaminophen lowers glutathione Tylenol, Autism, And The Connection • OC Integrative Medicine Let's provide some clarity here….

Why GHK-Cu

Multiple lines of evidence suggests that tumor cells have evolved to survive within the hypoxic and acidic environment, in part, by upregulating GSH-dependent antioxidant enzymes, including glutathione peroxidases and glutathione reductase and GSH content [157]

With one or more MTHFR mutations and a reduced ability to methylate, your body wont convert as much

So far GHK-Cu has the best research and it seems to have promise when used topically for cosmetic purposes

Dietary glutathione protects rats from diabetic nephropathy and neuropathy. The Journal of nutrition 132.5 (2002): 897-900

doi:10.1592/phco.31.6.591