Nutritional Supplement

Methionine

Also indexed as: L-Methionine

Possible Deficiencies

Most people consume plenty of methionine through a typical diet. Lower intakes during pregnancy have been associated with neural tube defects in newborns, but the significance of this is not yet clear.8

Side Effects

Animal studies suggest that diets high in methionine, in the presence of B-vitamin deficiencies, may increase the risk for atherosclerosis (hardening of the arteries) by increasing blood levels of cholesterol and a compound called homocysteine.9 This idea has not yet been tested in humans. Excessive methionine intake, together with inadequate intake of folic acid, vitamin B6, and vitamin B12, can increase the conversion of methionine to homocysteine—a substance linked to heart disease and stroke. Even in the absence of a deficiency of folic acid, B6, or B12, megadoses of methionine (7 grams per day) have been found to cause elevations in blood levels of homocysteine.10 Whether such an increase would create a significant hazard for humans taking supplemental methionine has not been established. Supplementation of up to 2 grams of methionine daily for long periods of time has not been reported to cause any serious side effects.11

References

1. Muller F, Svardal AM, Aukrust P, et al. Elevated plasma concentration of reduced homocysteine in patients with human immunodeficiency virus infection. Am J Clin Nutr 1996;242-6.

2. Revillard JP. Lipid peroxidation in Human Immunodeficiency Virus infection. J Acquired Immunodef Synd 1992;5:637-8.

3. Singer P, Katz DP, Dillon L, et al. Nutritional aspects of the acquired immunodeficiency syndrome. Am J Gastroenterol 1992;87:265-73.

4. Tan SV, Guiloff RJ. Hypothesis on the pathogenesis of vacuolar myelopathy, dementia, and peripheral neuropathy in AIDS. J Neurol Neurosurg Psychiat 1998;65:23-8.

5. Keating JN, Trimble KC, Mulcahy F, et al. Evidence of brain methyltransferase inhibition and early brain involvement in HIV-positive patients. Lancet 1991;337:935-9.

6. Dorfman D, DiRocco A, Simpson D, et al. Oral methionine may improve neuropsychological function in patients with AIDS myelopathy: results of an open-label trial. AIDS 1997;11:1066-7.

7. Valesini G, Barnaba V, Benvenuto R, et al. A calf thymus lysate improves clinical symptoms and T-cell defects in the early stages of HIV infection: Second report. Eur J Cancer Clin Oncol 1987;23:1915-9.

8. Shaw GM, Velie EM, Schaffer DM. Is dietary intake of methionine associated with a reduction in risk for neural tube defect-associated pregnancies? Teratology 1997;56:295-9.

9. Toborek M, Hennig B. Is methionine an atherogenic amino acid? J Optimal Nutr 1994;3:80-3.

10. McAuley DF, Hanratty CG, McGurk C, et al. Effect of methionine supplementation on endothelial function, plasma homocysteine, and lipid peroxidation. J Toxicol Clin Toxicol 1999;37:435-40.

11. Leach FN, Braganza JM. Methionine is important in treatment of chronic pancreatitis. Br Med J 1998;316:474 [letter].

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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2025.