Amino Acid Derivatives: Neurotransmitters, Nitric Oxide, and More The Medical Biochemistry Page Frontiers Metabolism of Amino Acids in Cancer Frontiers Cysteine Depletion, a Key Action to Challenge Cancer Cells to Ferroptotic Cell Death Our ancestors ate whole animals. Skin, cartilage, tendons, bones, organs. That meant they consumed massive amounts of glycine from collagen rich tissues. Modern humans eat almost exclusively muscle meat, which is extremely high