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amino acid
lysine
Nutrition
definition
L-Lysine: an essential amino acid
» metabolism:
Lysine is one of the essential amino acids. It is found highest in muscles with only glutamic acid and aspartic acid being higher. Lysine is degraded to acetyl CoA, a critical intermediate in the Kreb cycle. Enzymes involved with acetyl CoA have been found in decreasing order in the liver, kidneys, heart, adrenal glands, thymus gland, brain and skin. Lysine is the precursor to carnitine and citrulline. Minor amounts of lysine can be made into pipecolic acid, a neurotransmitter in the brain, and it works with the help of niacin. Arginine and ornithine are antagonistic to lysine and if given in large amounts can lead to a deficiency of lysine.
There are some inborn errors in metabolism which can lead to an elevation of lysine. High amounts of lysine can result in mental retardation along with a host of different physical abnormalities including delayed sex development, facial bone abnormalities, enlarged liver and obesity. Lysine is metabolized with the help of vitamins B-2 and B-3.
» function:
Lysine is involved with the synthesis of connective tissue, brain neurotransmitters and carbohydrate metabolism through its role as a precursor to acetyl CoA.
Precursor to citrulline and carnitine
» Chinese:
Nourishes the Xue (Blood); promotes the growth of new tissue; may benefit the Jing (Essence).
» requirements:
RDA:
Adults: 840 mg/day or 12 mg/kg body weight per day.
Children below twelve: 44 mg/kg per day.
Infants: 97 mg/kg per day.
Average intake in the U.S.: 70 mg to 80 per day.
» food sources:
Wheat germ, meat, eggs, fish, poultry, cheese, lima beans, shrimp, mung bean sprouts, cottage cheese, yeast
Best Sources of Lysine together with Arginine
Food Amount mg Lysine mg Arginine Ratio Arg/Lys
Turkey 3 oz 2100 1457 .69
Halibut, baked 3 oz 2083 1357 .65
Salmon 3 oz 2014 1311 .65
Liver, beef 3 oz 1671 1363 .82
Cheese 3 oz 1650 600 .4
Cheese, Ricotta 1/2 cup 1600 800 .5
Pork 3 oz 1586 1320 .83
Cheese, cheddar 3 oz 1497 729 .49
Wild game 3 oz 1300 962 .75
Cheese, cottage 1/2 cup 1200 700 .6
Sardines, canned in oil 3 med 814 531 .65
Meat, luncheon 3 oz 740 592 .8
Yogurt 1 cup 700 250 .35
Milk, whole 1 cup 650 300 .45
Beans, red canned 1/2 cup 630 510 .8
Oatmeal flakes 1 cup 600 600 1.0
Carrot juice 1/2 cup 600 480 .8
Granola 1 cup 500 900 1.85
Wheat germ, toasted 1/4 cup 500 675 1.3
Bacon 3 slices 500 525 .9
Duck 3 oz 480 407 .85
Sausage 3 oz 420 315 .8
Egg 1 med 400 400 1.0
Chicken 3 oz 370 278 .8
Peanuts 1/4 cup 363 1080 3.0
Avocado 1 med 200 100 .5
Cashews 10 nuts 185 490 2.6
Almonds 18 nuts 145 683 4.7
(USDA: Composition of Foods. USDA Handbook #8 Washington DC, ARS, USDA, 1976-1986)
» deficiency:
Certain vegetarian foods can be found to be deficient in lysine.
Refined grains, corn, sunflower seeds, peanuts, and vegetables are generally low in lysine.
In vegetarian diets legumes are used to supply the needed lysine.
Deficiency symptoms usually show a decreased immune function as well as decreased growth.
Special note: Lysine is involved in a reaction in foods called Caramelization. This reaction is also called the Maillard Reaction or Browning Reaction. It takes place in foods such as pastries, doughnuts, cookies, puffed and flaked cereals which contain lysine and simple sugars. When, during preparation, these foods are heated, a sugar hooks onto the lysine moiety of the protein chain. The body is unable to hydrolyze the protein chain that contains this caramelized lysine molecule. Absorption of this peptide can trigger immune responses or allergies.
In addition, if a person already has borderline lysine levels, these foods can cause a deficiency in lysine. In fact, a study done in the '70's by Dr. Constance Kies of the University of Nebraska and Dr. William Caster of the University of Georgia examined 38 cereals on the growth of rats. The cereal was their sole source of nutrition. 20 of the cereals failed to keep the rats alive, while another 12 provided little or no growth. The only cereals that did well were fortified with soy protein which made up for the deficiency of lysine that occurred because of the Maillard reaction. Others, such as wheat germ, which do not have any sugars, did not cause a lysine deficiency. There may also be a connection with lysine deficiency and kidney stones (calcium oxalate) as well. (Marz, p. 82-83, 1997)
» therapeutics:
Herpes Simplex: 3-9 g per day in divided doses for acute conditions. For prevention 500-1500 mg per day Lysine is a well known inhibitor of the herpes virus. Patient should consume foods high in lysine, low in arginine: fish, cheese, brewer's yeast.
Osteoporosis: Lysine may effect calcium metabolism by increasing absorption and decreasing excretion. In animal studies lysine deficiency results in an increased excretion of calcium.
Aphthous ulcers: In rare cases lysine may have dramatic effects.
Atherosclerosis
Marasmus
Cranial nerve disorders: migraines, Bell's palsy, Meniere's disease
» dosage:
Maintenance: 500 mg-1 g/day
Therapeutic Range: 0.5-4 g/day
Herpes: 1 - 6 g/day during outbreak
500 mg/day to prevent attack
» toxicity:
In mice and chicks high intakes of lysine can cause increased cholesterol levels. In humans lysine has very little toxicity, even at high doses. Doses up to 8 g per day seem to be innocuous.
1.9 gm/kg IV given to rats (140 g in man equivalent dose) increase kidney toxicity to aminoglycoside antibiotics. In the absence of antibiotics no toxic effects have been noted.
» contraindications:
None known.
» interactions:
Lysine is an antagonist to arginine and could result in an arginine deficiency if taken in high amounts with borderline intakes of arginine.
As mentioned previously, lysine in cereals and other carbohydrate foods can interact and actually cause a lysine deficiency. Too many cereals, especially if they contain significant quantities of simple sugars can cause a lysine imbalance.
footnotes
Braverman and Pfeiffer, pp. 289-301
Marz, Russell. Medical Nutrition From Marz. Second Edition. Portland, OR. 1997
USDA: Composition of Foods. USDA Handbook #8. Washington DC, ARS, USDA, 1976-1986