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Lysine is an essential amino acid. This means that it must be obtained through the diet in adequate quantities to meet the body's needs.

Lysine is required in the body for the manufacture of carnitine, which is an amino acid used for the proper metabolism of fats. Lysine incorporated into proteins if often cross-linked, such as in the body proteins collagen and elastin (the major proteins of the body). Cross-linking of lysine to make proper collagen and elastin is dependent upon the enzyme lysloxidase, which requires copper. Copper deficiency, therefore, can result in imperfections in collagen or elastin. Lysine has also been found to stimulate the synthesis of cholesterol in the liver. High lysine to arginine ratio diets, as found in animal protein, stimulate cholesterol synthesis, whereas lower lysine to arginine ratio diets do not stimulate as much cholesterol synthesis.

Lysine deficiency can interfere with carnitine synthesis and have adverse impact upon fat metabolism to energy.

Lysine supplementation is helpful in the management of herpes infections. The mechanism of the action of lysine in the treatment of herpes infections is not yet known, but appears to have some effect upon the replication of the herpes virus in infected cells. Doses range between 400 and 1,000 mg.

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Method of Action

It is commonly a limiting amino acid in strict vegetarian diets in that it is in short supply in many vegetable grains. "Limiting amino acid" means that its shortage in the diet may limit the synthesis of body protein and enzymes.

An unusual feature of lysine metabolism is that the alpha-amino group does not equilibrate with the nitrogen pool, as it does with most amino acids. Lysine can actually be broken down by four different pathways and is one of the more closely regulated essential amino acids in intermediary metabolism. Lysine is used along with methionine in the manufacture of carnitine, which is important for fatty acid metabolism. Lysine is also very important for the synthesis of ribosomal proteins and its insufficiency in the diet can result in poor protein biosynthesis. By degradation of lysine to gamma-butyro betaine, it can then be converted on to carnitine. These steps require ascorbic acid (vitamin C) for their reactivity.

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Food Sources

Cottage cheese (dry) 3,500 mg/cup

Cottage cheese (crmd) 2,562 mg/cup

Fish & other seafoods 1,500-11,800 mg/lb

Meats 2,000-8,500 mg/lb

Poultry 4,500-6,500 mg/lb

Sesame seeds 1,200 mg/cup

Dry, whole lentils 3,000 mg/cup


Excessive intake of lysine can result in increased urinary spill of lysine and kidney problems; therefore, doses above 1,500 mg per day should not be used. Because lysine has an effect on cholesterol synthesis in the liver, its use may slightly elevated LDL cholesterol.

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