AMINO ACIDS WITH IMPORTANT METABOLITES
- Lysine – Herpes Killer
- Carnitine – Heart Tonic
- Histidine – Arthritis Fighter
Lysine – Herpes Killer
L-lysine is an essential amino acid. Experimental animals on a lysine-deficient diet showed depressed growth and altered immune system function for several generations.
Normal requirements for lysine have been found to be about 8 g per day or 12 mg/kg in adults. Children and infants need more- 44 mg/kg per day for an eleven to-twelve-year old, and 97 mg/kg per day for three-to six-month old. Lysine is highly concentrated in muscle compared to most other amino acids.
Lysine is high in foods such as wheat germ, cottage cheese and chicken. Of meat products, wild game and pork have the highest concentration of lysine. Fruits and vegetables contain little lysine, except avocados.
Normal lysine metabolism is dependent upon many nutrients including niacin, vitamin B6, riboflavin, vitamin C, glutamic acid and iron. Excess arginine antagonizes lysine.
Several inborn errors of lysine metabolism are known. Most are marked by mental retardation with occasional diverse symptoms such as absence of secondary sex characteristics, undescended testes, abnormal facial structure, anemia, obesity, enlarged liver and spleen, and eye muscle imbalance.
Lysine is particularly useful in therapy for marasmus (wasting) and herpes simplex. It stops the growth of herpes simplex in culture, and has helped to reduce the number and occurrence of cold sores in clinical studies. Dosing has not been adequately studied, but beneficial clinical effects occur in doses ranging from 100 mg to 4 g a day. Higher doses may also be useful, and toxicity has not been reported in doses as high as 8 g per day. Diets high in lysine and low in arginine can be useful in the prevention and treatment of herpes. Some researchers think herpes simplex virus is involved in many other diseases related to cranial nerves such as migraines, Bell's palsy and Meniere's disease. Herpes blister fluid will produce a fatal encephalitis in the rabbit.
Lysine also may be a useful adjunct in the treatment of osteoporosis. Although high protein diets result in loss of large amounts of calcium in urine, so does lysine deficiency. Lysine may be an adjunct therapy because it reduces calcium losses in urine. Lysine deficiency also may result in immunodeficiency. Requirements for this amino acid are probably increased by stress.
Lysine toxicity has not occurred with oral doses in humans. Lysine dosages are presently too small and may fail to reach the concentrations necessary to prove potential therapeutic applications. Lysine metabolites, amino caproic acid and carnitine have already shown their therapeutic potential. Thirty grams daily of amino caproic acid has been used as an initial daily dose in treating blood clotting disorders, indicating that the proper doses of lysine, its precursor, have yet to be used in medicine.
Low lysine levels have been found in patients with Parkinson's, hypothyroidism, kidney disease, asthma and depression. The exact significance of these levels is unclear, yet lysine therapy can normalize the level and has been associated with improvement of some patients with these conditions.
Abnormally elevated hydroxylysines have been found in virtually all chronic degenerative diseases and coumadin therapy. The levels of this stress marker may be improved by high doses of vitamin C.
Carnitine – Heart Tonic
Carnitine is not an essential amino acid; it can be synthesized in the body. However, it is so important in providing energy to muscles including the heart-that some researchers are now recommending carnitine supplements in the diet, particularly for people who do not consume much red meat, the main food source for carnitine.
Even the Physician's Desk Reference gives indication for carnitine supplements as "improving the tolerance of ischemic heart disease, myocardial insufficiencies, and type IV hyperlipoproteinemia. Carnitine deficiency is noted in abnormal liver function, renal dialysis patients, and severe to moderate muscular weakness with associated anorexia."
Carnitine has been described as a vitamin, an amino acid, or a metabimin, i.e., an essential metabolite. Vitamins are defined as substances essential to the body that the body cannot manufacture itself. Like the B vitamins, carnitine contains nitrogen and is very soluble in water, and to some researchers carnitine is a vitamin (Liebovitz 1984). It was found that an animal (yellow mealworm) could not grow without carnitine in its diet. However, as it turned out, almost all other animals, including humans, do make their own carnitine; thus, it is no longer considered a vitamin. Nevertheless, in certain circumstances-such as deficiencies of methionine, lysine or vitamin C or kidney dialysis--camitine shortages develop. Under these conditions, carnitine must be absorbed from food, and for this reason it is sometimes referred to as a "metabimin" or a conditionally essential metabolite.
Like the other amino acids used or manufactured by the body, carnitine is an amine. But like choline, which is sometimes considered to be a B vitamin, carnitine is also an alcohol (specifically, a trimethylated carboxy-alcohol). Thus, carnitine is an unusual amino acid and has different functions than most other amino acids, which are most usually employed by the body in the construction of protein.
Carnitine is an important amino acid made by the body from lysine. Its most important known metabolic function is to transport fat into the mitochondria of muscle cells, including those in the heart, for oxidation. This is how the heart gets most of its energy. Inborn errors of carnitine metabolism can lead to brain deterioration like that of Reye's syndrome, gradually worsening muscle weakness, Duchenne-like muscular dystrophy and extreme muscle weakness with fat accumulation in muscles. Borurn et al. (1979) have summed up the research by describing carnitine as an essential nutrient for pre-term babies, certain types (non-ketotic) of hypoglycemics, kidney dialysis patients, cirrhotics, and in kwashiorkor, type IV hyperlipidemia, heart muscle disease (cardiomyopathy), and propionic or organic aciduria (acid urine resulting from genetic or other anomalies). In all these conditions and the inborn errors of carnitine metabolism, carnitine is essential to life and carnitine supplements are valuable.
Carnitine therapy may also be useful in a wide variety of clinical conditions. Carnitine supplementation has improved some patients who have angina secondary to coronary artery disease. It may be worth a trial in any form of hyperlipidemia or muscle weakness. Carnitine supplements may be useful in many forms of toxic or metabolic liver disease and in cases of heart muscle disease. Hearts undergoing severe arrhythmia quickly deplete their stores of carnitine. Athletes, particularly in Europe, have used carnitine supplements for improved endurance. Carnitine may improve muscle building by improving fat utilization and may even be useful in treating obesity. Carnitine joins a long list of nutrients which may be of value in treating pregnant women, hypothyroid individuals, and male infertility due to low motility of sperm.
SEE ALSO MISC. NUTRIENTS SECTION
Histidine – The Arthritis Fighter
Histidine is an essential amino acid for infants but not adults. Infants four to six months old require 33 mg/kg of histidine. It is not clear how adults make small amounts of histidine, and dietary sources probably account for most of the histidine in the body. Inborn errors of histidine metabolism exist and are marked by increased histidine levels in the blood. Elevated blood histidine is accompanied by a wide range of symptoms, from mental and physical retardation to poor intellectual functioning, emotional instability, tremor, ataxia and psychosis.
Histidine in medical therapies has its most promising trials in rheumatoid arthritis where up to 4.5 g daily have been used effectively in severely affected patients. Arthritis patients have been found to have low serum histidine levels, apparently because of too-rapid removal of histidine from their blood. Histidine and other imidazole compounds have antiinflammatory properties. Histidine may accomplish this function through a complex interaction with threonine or cysteine and possibly copper. However, copper is usually elevated in rheumatoid arthritis patients and worsens the disease.
Other patients besides arthritis patients that have been found to be low in serum histidine are those with chronic renal failure. Histidine has been claimed to have been useful in hypertension because of its vasodilatory effects. Claims of its use to improve libido and counteract allergy are without proof at present.
Histidine may have many other possible functions because it is the precursor of the ubiquitous neurohormone-neurotransmitter histamine. Histidine increases histamine in the blood and probably in the brain. Low blood histamine with low serum histidine occurs in rheumatoid arthritis patients. Low blood histamine also occurs in some manic, schizophrenic, high copper and hyperactive groups of psychiatric patients. Histidine is a useful therapy in all low histamine patients.
Effective therapeutic doses of histidine may range from 1 to 5 g per day. Therapy can be guided by measuring plasma histidine levels.
SUMMARY OF AMINO ACID FUNCTIONS
*Treatment of Herpes Simplex
*Aid in promoting bone frowth
*Helps form collagen in connective tissue
*Assures adequate absorption of calcium
*Replaces L-Lysine destroyed in food processing
*Useful in the management of ischemic heart
*Prevents the accumulation of ketones during weight
*Improves fat metabolism
*Reduces blood triglycerides
*Helps use fat as an energy source for the heart
*Effective for cardiocirculatory diseases providing
vasodilating & hypotensive action.
*Effective in treating allergic disease.
*Treatment of peptic ulcer
*Treatment of anemia
*Treatment of rheumatoid arthritis
*Needed for production of red & white blood cells