Homocysteine: Diagnostic Significance and Clinical Insights Advanced Health Academy 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, Glutathione: Physiological and Clinical Relevance Restorative Medicine One lab marker could reveal your risk for heart disease, brain decline, and poor detoxand most people have never heard of it.