Vitamins, Minerals and Dietary Supplements
What is methionine? Why do we need it?
Methionine is one of the essential amino acids. It is responsible
for supplying sulfur and other elements used by the body for
metabolism and growth. Methionine belongs to a collection
of compounds called lipotropics, a group that includes choline
and inositol.
People with AIDS have been shown to have low methionine levels,
which has led some researchers to speculate that some AIDS-related
nervous disorders are caused by a lack of methionine. A small
study published in 1997 demonstrated that methionine supplements
could improve memory in AIDS patients. An early study published
in 1984 hinted that methionine may treat some symptoms of
Parkinson's disease; however, subsequent studies have
shown that another form of methionine, S-adenosylmethionine
(or SAMe) may actually worsen Parkinson's symptoms.
How much methionine should I take?
The required amount of amino acids depends on a person's
body weight; researchers believe the average adult requires
approximately 800-1,000mg of methionine per day. Since this
amount is exceeded by most Western diets, it is believed that
methionine supplementation is usually not necessary.
What are some good sources of methionine?
What forms are available?
Meat, fish and dairy products are all good sources of methionine.
Methionine capsules are also available at most health food
stores.
What can happen if I don't get enough
methionine? What can happen if I take too much? Are there
any side-effects I should be aware of?
Low intakes of methionine during pregnancy have been associated
with neural tube defects in newborn children. Excessive amounts
of methionine in the diet may increase blood cholesterol levels,
which could lead to atherosclerosis and cardiovascular disease.
This effect appears to be present especially if there is an
inadequate intake of folic acid, vitamin B6 and vitamin B12.
At present, there are no known drug interactions with methionine.
References
- Cheng H, Gomes-Trolin C, Aquilonius SM,
et al. Levels of L-methionine S-adenosyltransferase activity
in erythrocytes and concentrations of S-adenosylmethionine
and S-adenosylhomocysteine in whole blood of patients with
Parkinson's disease. Exp Neurol 1997;145:580—5.
- 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.
- 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.
- 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.
- Toborek M, Hennig B. Is methionine an
atherogenic amino acid? J Optimalt Nutr 1994;3(2):80—3.
