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 Reactive metabolites and antioxidant gene polymorphisms in Type 2 diabetes mellitus ScienceDirect Molecular Genetics of Abnormal Redox Homeostasis in Type 2 Diabetes Mellitus Frontiers Glutathione deficiency in the pathogenesis of SARS CoV 2 infection and its effects upon the host immune response in severe COVID 19 disease Cholesterol metabolism and its role in type 2 diabetes mellitus development Food, Nutrition and Health Springer Nature Link