L-Methionine

L- Methionine is classified as an essential amino acid and therefore must be required by the diet. L-methionine is an amino acid that contains sulphur in the chemical structure and is minimally soluble in water. The molecular formula is C5H11NO2S, and its molecular weight is 149.21 daltons. L-methionine is also known as (S)-2-amino-4-(methylthio)butanoic acid, 2-amino-4-(methylthio)butyric acid, alpha-amino-gamma-methylmercaptobutyric acid, and gamma-methyl-thio-alpha-aminobutyric acid. It is abbreviated as Met and its one letter abbreviation is M. The terms L-methionine and methionine are used interchangeably.

The mineral sulphur, which is found within the methionine structure, is a vital nutrient for our bodies. Sulphur protects the cells from pollution such as exhaust and industrial smoke. It has been found to slow down the aging process in the cells and aids in the production of protein. Sulphur is needed for healthy skin, bones, organs, and hair. Sulphur also helps to transport important elements such as selenium and zinc around the body, and, in compound form, has been found to protect the body against radiation. Every day, we use up or excrete about 100 mg of sulphur. Besides sulphur being in methionine it is also found in the amino acids cysteine, cystine, and taurine.

Function- As levels of toxic substances in the body increase, the need for methionine increases. The body can convert methionine into the amino acid cysteine, a precursor of glutathione. Glutathione is a key neutralizer of toxins in the liver; thus protecting the liver from the damaging effects of toxic compounds. Methionine therefore prevents glutathione depletion if the body is overloaded with toxins. Toxins can be in the form of pollution, preservatives, medication, drugs, and heavy metals. Unfortunately, in day to day life, we are exposed to these toxins in large amounts. Methionine is an excellent chelator, which means that it can locate these damaging elements then literally grab onto them and eliminate them from the body.

In addition to its role as a precursor in protein synthesis, L-methionine participates in a wide range of metabolic reactions including the production of S-adenosylmethionine (SAM or SAMe), L-cysteine, glutathione, taurine and sulfate. SAMe itself is involved in the synthesis of creatine, epinephrine, adrenalin, melatonin and the polyamines spermine and spermidine, among several other substances. L-methionine is also a glycogenic amino acid and may participate in the formation of D-glucose and glycogen.

Because the body uses methionine to create a brain food called choline, it is wise to supplement the diet with choline or lecithin (which is high in choline) to ensure that the adequate supply of methionine is not depleted. L-methionine has been found to reduce the liver toxic effects from medications such as acetaminophen and methotrexate.

Deficiency- Conditions related to a methionine deficiency are hyperactivity, skin and nail conditions, emphysema, premature aging, chronic depression, premature ejaculation, elevated levels of toxins and heavy metals, arthritis, neurological disorders, brittle hair, allergies, adrenal fatigue, exhaustion and liver dysfunction. Low levels of methionine are found in those suffering from mental disorders and schizophrenia. Methionine is effective in decreasing the elevated levels of histamine in these patients.

Sources- Methionine is found in eggs, fish, garlic, lentils, meat, poultry, onions, soybeans, seeds, yogurt, cheese and most dairy products. Vegetarians will almost certainly benefit from supplementing their normal diets with methionine because it is low in most vegetables and legumes.

Precautions- Methionine should be avoided by those with elevated homocysteine levels (homocystinuria). Homocysteine is a normal by product of methionine metabolism, however, if this pathway accumulates an excessive amount of homocysteine it relates significantly to cardiovascular disease. This is not the fault of methionine but a deficiency in synergistic nutrients.

Requirements- There is no Recommended Dietary Allowances (RDA) listed. Individual needs may differ due to clinical conditions, biochemical individuality and absorption. All sources of nutrients should be consumed in their most natural state, in the form of a variety of foods or supplements when necessary. Free form amino acid supplements are immediately absorbed by the body and should be consumed with natural occurring cofactors for best results. Consulting with a physician that is properly trained in the natural healing sciences and amino acid therapy may be needed for optimum results.

Written by Jerome Rerucha D.C.

References-
1. Batova A, Diccianni MB, Nobori T, Vu T, Yu J, Bridgeman L, Yu AL 1996 Frequent deletion in the methylthioadenosine phosphorylase gene in T-cell acute lymphoblastic leukemia: strategies for enzyme-targeted therapy. Blood 88: 3083-3090.
2. Guranowski A, Paszewski A 1982 Metabolism of 5'-methylthioadenosine in Aspergillus nidulans. An alternative pathway for methionine synthesis via utilization of the nucleoside methylthio group. Biochim. Biophys. Acta 717: 289-294.
3. Myers RW, Wray JW, Fish S, Abeles RH 1993 Purification and characterization of an enzyme involved in oxidative carbon-carbon bond cleavage reactions in the methionine salvage pathway of Klebsiella pneumoniae. J. Biol. Chem. 268: 24785-24791.
4. Wray JW, Abeles RH 1995 The methionine salvage pathway in Klebsiella pneumoniae and rat liver. Identification and characterization of two novel dioxygenases. J. Biol. Chem. 270: 3147-3153.
5. 1. Farley D. Benefit vs. risk: How the FDA approves new drugs. FDA Consumer Special Issue: From Test Tube to Patient: New Drug Development in the United States. 2nd ed U.S. Food and Drug Administration
6. Kurtzweil P, An FDA guide to dietary supplements. U.S. Food and Drug Administration.
7. Overview of dietary supplements. U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition.
8. Di Padova C. S-Adenosylmethionine in the treatment of osteoarthritis, A review of the clinical studies. Am J Med. 1987;83(suppl 5A):60-65.
9. Konig B. A long-term (two years) clinical trial with S-adenosylmethionine for the treatment of osteoarthritis. Am J Med. 1987;83(Suppl 5A):89-94.
10. Frezza M, Surrenti C, Manzillo G et al. Oral S-adenosylmethionine in the symptomatic treatment of intrahepatic cholestasis, A double-blind, placebo controlled study. Gastroenterology. 1990;99:211-215.
11. Arthritis Foundation- SAM-e (S-adenosyl-methionine). Arthritis Foundation. Available: URL. http://www. arthritis.org/resource/statement /sam%5Fe.asp. Accessed 1999 June.
12. Clausen, T., Huber, R., Prade, L., Wahl, M.C., and Messerchmidt, A. (1998) Crystal structure of cystathionine g-synthase from E. coli at 1.5 Å resolution. EMBO J. 17, 6827-6838.
13. Nakayama, T., Esaki, N., Tanaka, H., and Soda, K. (1988) Chemical modification of cysteine residues of L-methionine g-lyase. Agric. Biol. Chem. 52, 177-183.
14. MacKie, A.E., Edlind, T., Walker, J., Mottram, J.C., and Coombs, G.H. (1998) The primitive Protozoon Trichomonas vaginalis contains two methionine g-lyase genes that encode members of the g-family of pyridoxal 5'-phosphate-dependent enzymes. J. Biol. Chem. 273, 5549-5556