The amino acid methionine is required in the diet and thus is considered an essential amino acid. Methionine helps in the biochemical breakdown of fats in the body; this action prevents the accumulation of fat in the liver and in the arteries - a situation that may actually obstruct the blood flow towards the brain, the heart and the kidneys. The availability of methionine in the body may affect the biochemical synthesis of the amino acids cysteine and taurine. The digestive system is also aided by this amino acid. Methionine also aids in the rapid detoxification of harmful compounds such as lead and any other heavy metals which may cause toxic side effects due to their presence in the body. Methionine also actively reduces the onset of muscular weakness, it prevents metabolic events that induce brittle hair and also protects against radiation. Methionine is also believed to be beneficial for people affected by osteoporosis or those affected by chemical allergies. The amino acid is also said to be beneficial for treating rheumatic fever and toxemia arising during pregnancy in women.
A notable role of methionine is its powerful antioxidant action against free radicals produced in the natural metabolic processes of the body. The amino acid methionine is also an excellent source for the essential mineral sulfur, which quickly inactivates free radicals produced in the body. People affected by Gilbert's syndrome, which results in an anomaly of liver functioning are also benefited by supplements of the amino acid methionine. The amino acid is also required during the synthesis of nucleic acids, collagen and different proteins found in almost every cell of the human body - it is a constituent of many enzymes and proteins found in different parts of the body. Women who take oral contraceptives also benefit from supplements of the amino acid methionine as it promotes the excretion of estrogen from the body. The amino acid methionine also reduces the level of histamine present in the body, this property of the amino acid is considered very useful for people affected by schizophrenia and related conditions, in whom the levels of histamine are generally higher than those found in normal healthy adults.
The requirement for methionine tends to increase when accumulated levels of different toxic substances found in the body increase. Methionine in the body can be converted into the amino acid cysteine, which itself is a precursor of the vital compound called glutathione. Glutathione is thus afforded a level of protection by methionine, as levels of methionine prevent the depletion of glutathione when the body becomes overloaded with accumulated toxins and chemicals. Glutathione is also a vital neutralizer of toxins present in the liver; the chemical thus protects the liver from the damaging effects of toxic compounds produced as a result of general metabolism.
Methionine is not synthesized in the human body and is considered to be an essential amino acid. It needs to be obtained in the diet from methionine rich food sources or via dietary supplements of methionine or protein rich complexes. Food sources which abound in methionine include foods such as beans, eggs and fish, various lentils, poultry and meat, onions and garlic, soybeans, seeds and yogurt. Methionine is used by the body to synthesize a particular molecular brain food called choline. Diets must be supplemented either with choline or lecithin - another compound high in choline - so as to ensure an adequate supply of methionine at all times.
The levels of the neuro-transmitting substances such as dopamine, nor-epinephrine and epinephrine are increased by methionine. The amino acid is also utilized in controlling hypertension; it is used to lower the potency of allergic symptoms in people affected by such conditions. Methionine is also used to bring relief from chronic pain and as an aid to reduce all kinds of inflammation. It is also used to lower cholesterol and to protect the person from the bad effects of aspirin and related chemicals. Methionine supplements are also beneficial in the treatment of Parkinson's disease and schizophrenia especially in the early stages.
A lot of methionine is generally consumed by the majority of people as a part of total proteins in the average diet. However, neural tube defects in new born babies has been linked to lowered intake of methionine - the real significance of this observation is still not charted and there may be a possible relation between normal fetal development and levels of methionine in the body of expectant mothers.
The body weight of a person determines their daily amino acid requirements and this requirement spans a range of values for different body types. Approximately 800 - 1,000 mg of methionine is required by an average sized adult per day; this is an amount of the amino acid that is exceeded by the total methionine intake found in the majority of diets in the western world. Methionine supplementation is therefore unlikely to be of great benefit to the majority of people in the West.
The evidence gained from animal studies suggests that normal diets that are high in methionine content, especially when accompanied by deficiencies of the B vitamin complex, could possibly heighten the risk of atherosclerosis - which is the hardening of the arteries. This situation may come about due to an increase in the levels of cholesterol in the blood and higher levels of a compound called homocysteine in the body. Human tests conducted in the laboratory have not sufficiently tested out this hypothesis and further study is needed. The evidence however points to the fact that high methionine intake in the diet, if combined with deficiency in folic acid, vitamin B6 and vitamin B12 levels in the body, can lead to a great increase in the conversion of methionine to the compound called homocysteine. This compound is a chemical substance connected to heart disease and stroke in patients. The link between supplemental methionine and this relationship with deficiencies of the B vitamins has not been studied and whether or not this connection is a qualified hazard for humans using supplements of methionine must be established in further studies. No severe effects health wise has been registered in any patients who supplemented with up to two grams of methionine per day, even for long periods of time.