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, A Functional Transsulfuration Pathway in the Brain Links to Glutathione Homeostasis* Journal of Biological Chemistry Amazon.com: Pure Encapsulations L Methionine Glutathione and Amino Acid Supplement for Joints, Liver and Pancreas Support, Antioxidants, and Nervous System* 60 Capsules : Health & Household 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 Methionine Wikipedia