Introduction

  •      2-amino-4-methylsulfanylbutanoic acid
         (C5H11NO2S)

  •      Methionine is a sulfur containing essential amino acid Racemethionine is a racemic mixture of d and l-methionine which are mirror images of each other.

  • Functions Of Racemethionine :-

    • Methyl (-CH3) donor – It is important in metabolic processes where methyl group is transferred to other compound (methylation).

    • A precursor to other important substances like S-adenosyl methionine (SAMe), glutathione and amino acids like taurine and cysteine.

  • Lipotropic Action :-

    • A lipotropic nutrient is one that promotes or encourages the export of fat from the liver. Methionine is necessary for the maintenance of a healthy liver as well as burning the exported fat for additional energy. Without lipotropics (like methionine), fats and bile become trapped in the liver, causing severe problems such as cirrhosis (death of cells) and blocking fat metabolism.

    • By breakdown of fats it prevents the build-up of fat in the arteries and in liver.

  • Liver Detoxification :-

    • Methionine acts as a chelator, binding to heavy metals and removing them from the body before they can build up and cause damage to tissues.

    • It removes heavy metals from the body since it can be converted to cysteine, which is a precursor to glutathione – the master detoxifier in the liver.

  • Antioxidant And Source Of Sulfur :-

    • Methionine reconstitutes an important antioxidant defense mechanism. It neutralizes a variety of oxidants forming methionine sulfoxide thus scavenges free radicals. Methionine sulfoxide is reconverted in to methionine again by enzyme action. This example points out that cyclic oxidation and reduction of methionine residues both scavenges H2O2, superoxide, ozone, hypochlorous acid, and chloramines2.

    • The median and maximum life spans in insects Zaprionus paravittiger increased with methionine feeding. It was accompanied by higher catalase and peroxidase enzyme activities. The findings indicate that a life-prolonging effect of methionine on Z. paravittiger may be by virtue of its free radical scavenging effect3.

  • Methionine Also Acts As Antioxidant By Being A Source of sulfur :-

    • The body uses sulfur to influence hair follicles and promote healthy hair, skin, and nail growth. Sulfur also increases the liver's production of lecithin (which reduces cholesterol), reduces liver fat, protects kidneys, helps body to excrete heavy metals, and reduces bladder irritation by regulating the formation of ammonia in the urine.

    • In women, it is beneficial for them who take oral contraceptives because it promotes the excretion of estrogen and thus reduces PMS (premenstrual syndrome).

  • Deficiency Symptoms :-

    • Severe deficiency may manifest in dementia, while lesser deficiencies may be known by symptoms like fatty liver, slow growth, weakness, edema and skin lesions. Diets deficient in this essential amino acid may result in a destructive breakdown and metabolism of protein.

  • Food Sources :-

    • Methionine is considered as essential amino acid because it cannot be manufactured in the body and must be obtained through diet. This particular amino acid is found only in meat, fish, eggs, and dairy products. It easily gets destroyed during cooking processes making supplementation more necessary.

    • Methionine supplements are often recommended for those who are not getting a proper diet, such as vegetarians who might not be getting a balance of complete protein, athletes, people under severe stress, and anyone whose alcohol intake level is moderate to high.

  • Side Effects :-

    • There appears to be no toxic dosage of methionine, but it may cause nausea, vomiting, drowsiness and irritability with higher dosage. Supplementation of up to 2 g methionine daily for long periods of time has not produced any serious side effects.

    • 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 – this theory has not been proven in humans.