Methionine is an essential amino acid—one of the building blocks of proteins and peptides that your body cannot manufacture from other chemicals. The body uses methionine to manufacture creatine and uses the sulfur in methionine for normal metabolism and growth.
One preliminary study suggests that methionine can prevent bacteria from sticking to urinary tract cells,1 which may make it useful for preventing bladder infections. ( Cranberry juice is thought to help reduce the incidence of bladder infections in a similar fashion.)
Depending on your body weight, you need between 800 and 1,000 mg of methionine daily for normal health. Deficiency is unlikely because enough methionine is generally available from the diet.
Meat, fish, dairy products, and other high-protein foods are good sources of methionine.
A proper therapeutic dosage of methionine has not been determined. One study relating to urinary tract infections used a dosage of 500 mg 3 times daily. A study enrolling people with HIV used a dose of 800 mg three times daily.
Because it seems to discourage bacteria from sticking to the wall of the bladder, methionine has been suggested as a treatment for recurrent bladder infections.2 However, the evidence that it works is limited to one small trial without a placebo control. (For information on why placebo-controlled trials are essential to prove a treatment effective, see Why Does This Database Depend on Double-Blind Studies?)
One study on rats suggests that methionine might protect the liver against the damaging effects of acetaminophen poisoning.3 On this slim basis, methionine has been proposed as a general liver protectant. However, in this particular study, the action of methionine was more to fight acetaminophen specifically than to protect the liver in general.
Methionine is thought to be generally safe. However, the maximum safe dosages for young children, pregnant or nursing women, or those with serious liver or kidney disease have not been established.
If you are taking:
1. Funfstuck R, Straube E, Schildbach O, et al. Prevention of reinfection by L-methionine in patients with recurrent urinary tract infection [in German]. Med Klin. 1997;92:574-581.
2. Funfstuck R, Straube E, Schildbach O, et al. Prevention of reinfection by L-methionine in patients with recurrent urinary tract infection [in German]. Med Klin. 1997;92:574-581.
3. Neuvonen PJ, Tokola O, Toivonen ML, et al. Methionine in paracetamol tablets, a tool to reduce paracetamol toxicity. Int J Clin Pharmacol Ther Toxicol. 1985;23:497-500.
4. Smythies JR, Halsey JH. Treatment of Parkinson's disease with L-methionine. South Med J. 1984;77:1577.
5. Meininger V, Flamier A, Phan T, et al. L-methionine treatment of Parkinson's disease: preliminary results [in French]. Rev Neurol (Paris). 1982;138:297-303.
6. Nutt JG, Woodward WR, Hammerstad JP, et al. The "on-off" phenomenon in Parkinson's disease: relation to levodopa absorption and transport. N Engl J Med. 1984;310:483-488.
7. Toborek M, Hennig B. Is methionine an atherogenic amino acid? J Opt Nutr. 1994;3:80-83.
8. Van Brummelen R, du Toit D. L-methionine as immune supportive supplement: a clinical evaluation. Amino Acids. 2006 Sep 29 [Epub ahead of print]
Last reviewed July 2012 by EBSCO CAM Review Board
Last Updated: 7/25/2012
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