A sulfur containing essential amino acid that is important in many body functions. It is a chelating agent for heavy metals. [PubChem]
Indication
Used for protein synthesis including the formation of SAMe, L-homocysteine, L-cysteine, taurine, and sulfate.
Pharmacology
L-Methionine is a principle supplier of sulfur which prevents disorders of the hair, skin and nails; helps lower cholesterol levels by increasing the liver's production of lecithin; reduces liver fat and protects the kidneys; a natural chelating agent for heavy metals; regulates the formation of ammonia and creates ammonia-free urine which reduces bladder irritation; influences hair follicles and promotes hair growth. L-methionine may protect against the toxic effects of hepatotoxins, such as acetaminophen. Methionine may have antioxidant activity.
Toxicity
Doses of L-methionine of up to 250 mg daily are generally well tolerated. Higher doses may cause nausea, vomiting and headache. Healthy adults taking 8 grams of L-methionine daily for four days were found to have reduced serum folate levels and leucocytosis. Healthy adults taking 13.9 grams of L-methionine daily for five days were found to have changes in serum pH and potassium and increased urinary calcium excretion. Schizophrenic patients given 10 to 20 grams of L-methionine daily for two weeks developed functional psychoses. Single doses of 8 grams precipitated encephalopathy in patients with cirrhosis.
Affected Organisms
Humans and other mammals
Biotransformation
Hepatic
Absorption
Absorbed from the lumen of the small intestine into the enterocytes by an active transport process.
Other Notes Synthesis of labels for protonation studies by Fourier Transform Infrared Methods for L-glutaric-513C acid1; Spacer in isotachophoresis of serum proteins2; Essential in culture media for some malignant human cell lines3,4; Growth requirement of various microorganisms5
