Homocysteine and methionine are key amino acids with a vital connection to glutathione one of your body's most important substances! Methionine is abundant in many foods, so protein isn't the culprit, Frontiers Redox metabolism in cell senescence: focusing on contributions from the metabolomic field protein synthesis protein intake. you can eat a pound of steak and only ~32% of those amino acids actually become new protein in your body. the rest gets converted to glucose New Insights into the Roles of Cysteine and Homocysteine in Pathological Processes IntechOpen Critical Roles of the CysteineGlutathione Axis in the Production of Glutamyl Peptides in the Nervous System