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, Transsulfuration Activity Can Support Cell Growth upon Extracellular Cysteine Limitation: Cell Metabolism 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 Glutathione Metabolism in Yeasts and Construction of the Advanced Producers of This Tripeptide Springer Nature Link The Glutathione System: A New Drug Target in Neuroimmune Disorders Molecular Neurobiology Springer Nature Link