Methionine

Some important facts about Methionine:
Threonine contains two chiral centers, so there are four possible stereoisomers of threonine, or two possible diastereomers of L-threonine. However, the name L-threonine is used for one single enantiomer, (2S,3R)-2-amino-3-hydroxybutanoic acid. The second diastereomer (2S,3S), which is rarely present in nature, is called L-allo-threonine. The threonine side chain can undergo O-linked glycosylation. Threonine can become phosphorylated through the action of a threonine kinase. In its phosphorylated form, it can be referred to as phosphothreonine.

Use of methionine:
1. It is used for treating endometriosis, a condition in which patches of endometrial tissue from the uterine lining grow outside the uterus.
2. It also helps in the breakdown of fats and thereby prevents the build-up of fat in the arteries, as well as assisting with the digestive system and removing heavy metals from the body since it can be converted to cysteine, which is a precursor to gluthione, which is of prime importance in detoxifying the liver.
3. The amino acid methionine is also a great antioxidant as the sulfur it supplies inactivates free radicals.
4. It may also be used to treat depression, arthritis pain as well as chronic liver disease - although these claims are still under investigation. Some studies have also indicated that methionine might improve memory recall.
5. It is also one of the three amino acids needed by the body to manufacture creatine monohydrate, a compound essential for energy production and muscle building.
6. It also helps to maintain healthy skin tone, well-conditioned hair, and strong nails.
7. It also helps to increase the flow of bile and cell-damaging toxins away from the liver.
8. It helps to relieve the bleeding, cramps, pain, and other complications of endometriosis.

Deficiency symptoms of methionine:
Severe deficiency may result in dementia, while lesser deficiencies may be known by symptoms like fatty liver, slow growth, weakness, edema and skin lesions.

Symptoms of high intake:
It has been suggested that a high intake of methionine, in the presence of B vitamin deficiencies, may increase the risk for arteriosclerosis (hardening of the arteries) by increasing blood levels of cholesterol and a compound called homocysteine
Excessive methionine intake, with an inadequate intake of folic acid, vitamin B6 and vitamin B12, may increase the rate of conversion of methionine to homocysteine - both these theories have not been proven in humans.

When more is needed:
People with liver problems, pancreatitis, HIV/AIDS as well as Parkinson's disease may require high amounts of methionine in their diet but they should consult their physician before taking higher doses. Older people may also benefit from a slightly higher intake of this nutrient. Women on birth control pills could also benefit from this nutrient, since it promotes the excretion of estrogen. People suffering from schizophrenia could require extra methionine since it reduces the level of histidine in the body, a level normally higher in people suffering from schizophrenia.

Daily requirement:
The daily dosage of methionine is about 12 mg per kilogram of body weight per day - which would translate to about 840 mg for a 70 kg male.

Other important facts :
It is used with choline and inositol.
It is important in the process of methylation where methyl is added to compounds as well as being a precursor to the amino acids cystine and cysteine.
There are no known drug or nutrient interactions associated with methionine.
If you have any serious illness or are pregnant, only take an amino acid such as methionine after consulting your physician. To be safe, never take methionine--or any single amino acid for that matter--for longer than three months unless you are under the direction of a doctor familiar with its use.

Sources of methionine:
Methionine is found in good quantities in meat, fish, beans, eggs, garlic, lentils, onions, yogurt and seeds.
Other sources of methionine are cheese, eggs, chicken, and beef