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, Methionine dietary supplementation potentiates ionizing radiation induced gastrointestinal syndrome American Journal of Physiology Gastrointestinal and Liver Physiology American Physiological Society Methionine an overview ScienceDirect Topics Transsulfuration Pathway an overview ScienceDirect Topics