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Amino Acids


There are 8 Essential Amino Acids - that is amino acids which our bodies do not make on their own, these are Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan and Valine. Then there are 7 Semi- Essential Amino Acids - that is amino acids which under special circumstances may not be produced in adequate quantities by our bodies, these are Arginine, Carnitine, Cystine, Glycine, Histidine, Taurine and Tyrosine. There are at least 9 Non-Essential Amino Acids that are of general nutritional interest, these are Alanine, Aspartic Acid, Citrulline, Cysteine, GABA (gamma Aminobutyric Acid), Glutamic Acid, Ornithine, Proline and Serine.

There is much to tell on each of these and I will only attempt to write on *some* of the high points. However, PLEASE always remember 3 things:

  1. You need to know in general its pathway, that is, if possible, how does it function, what is it formed from, what is it transformed into and who are its "working partners"
  2. At some dose(s) it may be toxic (either too little, too much or both) and
  3. The metabolism is *highly* influenced by other nutrients, so taking a large dose of one may not have the desired effect.

Also we don't know as much as we should, hence consider that many salesmen, particularlly, if attempting to sell you a single amino acid supplement without well thought out reasoning, may be attempting to sell you the Golden Gate Bridge!!!


These 2 essential amino acids and Valine are often refered to as BCCAs, that is branched chain amino acids.

Leucine and isoleucine are major metabolic regulators. Isoleucine regulates some of the functions of niacin (Vitamin B3). Whereas, Leucine is primarily used in the muscles, where it functions as an energy source, stimulates protein synthesis and may be helpful in the release of Insulin. Leucine is primarily metabolized through fat pathways. Leucine inhibits the transport of Tryptophan in the brain and excess Leucine decreases the buildup of brain serotonin. Both Leucine and Isoleucine work synergistically with the B Vitamins, particularly B6 (Pyridoxine).

Lysine insures the adequate uptake of calcium. It helps in the formation of collagen and appears sometimes to be effective against Herpes. Together with Tryptophan, it may reduce cholesterol levels. Lysine is a precursor for Carnitine, and functions synergistically with Vitamins B6, B3, B2 (riboflavin) and C, Glutamic acid and iron. Lysine can be depleted by excess levels of Arginine and Ornithine.

Methionine is a sulfur containing amino acid. It has been found to reduce liver fats and help lower cholestrol levels by increasing the production of lecithin in the liver. It also chelates many environmental toxicants, including metals, in the liver.

Methionine is metabolized to and/or metabolically related to: serine, cystine, cysteine, taurine, choline, carnitine and glutathione. It is also functions synergistically with Vitamins B6, B12, folic acid and magnesium.

Used by the brain to produce Norepinephrine, which transmits nerve cell signals. Phenylalanine is an antidepressant and is thought to improve memory. Phenylalanine is a precursor for Tyrosine, which in turn, is the precursor for Cystine, both these latter amino acids are required by premature infants. Phenylalanine is depleted by caffeine and works synergistically with Vitamins B6, B3, C, some forms of folate and iron and copper. Phenylalanine supplements should not be taken with MAO (monoamineoxidase) drugs.

It is an important constituent of elastin, which is part of collagen. Threonine is an immune system stimulant and a primary nutrient for the thymus. It is a precursor for glycine and serine and works synergistically with Vitamin B6.

Due to the FDA ban this amino acid is not available over the counter. Tryptophan functions as a relaxant for anxiety, depression and migraine. It stimulates the immune system and reduces the risk of artery and heart spasms. Together with Lysine it can help reduce cholesterol levels. Tryptophan functions syngergistic with Vitamin B6, B3, magnesium and some forms of folate.

Valine is involved in the synthesis of vital proteins and peptides. It promotes mental vigor and muscle coordination. Valine, which is a branch chain amino acid (BCAA) and functions synergistically with Vitamin B6, B2, B1, biotin, copper and magnesium. Depleting factors include alcoholism, chronic liver diseases and stress.


Arginine is a part of the urea cycle and is derived from citrulline and aspartic and glutamic acids. Lysine is an antagonist. Arginine improves immune response to viruses and bacteria. It promotes wound healing and the regeneration of liver tissue by release of growth hormones. It occurs in very high quantities in seminal fluid. Depending on specific conditions arginine may sometimes be counted as an essential amino acid.

Carnitine is synthesized in the body from Lysine. It functions in the body is the provision of energy to the muscles, by the transport of fat into the mitochondria of the cells. Carnitine functions synergistically with lysine, methionine, Vitamins C, B3, iron and manganese. Carnitine is possibly an essential amino acid in premature infants.

Cystine is an oxidation product of Cysteine and it functions as an antioxidant. It is essential in premature infants. It can be metabolized from Tyrosine, which is itself metabolized from Phenylalanine.

Glycine helps produce carbohydrates in the body. It takes parts in the synthesis of glutathione and DNA/RNA precursors (purines). Glycine helps trigger the release of the oxygen required for cell production. Also it is important in the manufacture of the hormones required for the immune system. Glycine, proline and arginine help in wound healing. Depending on the specific conditions glycine may sometimes be counted as an essential amino acid.

It is essential in children and is a precursor of the vasodilator and neurotransmitter, histamine. It is essential for protein synthesis. Zinc at low doses may raise serum histidine levels. Histidine has been used in the treatment of rheumatoid arithritis. A deficiency in histadine can lead to hearing loss.

Taurine is a derivative of cysteine. Taurine influences blood sugar levels and is a neurotransmitter. It has been used in controlling epileptic seizures. Taurine functions synergistically with Vitamins B6, A, zinc and manganese. Taurine is probably an essential amino acid in premature infants. A supplement of taurine should not be taken together with aspirin, because of the potential for stomach ulcers from increased stomach acidity.

Tyrosine is a precursor of the brain neurotransmitters epinephrine, norepinephrine and dopamine. Thus it can help overcome depression and can improve memory. Tyrosine also promotes the functioning of the thyroid, adrenals and pituitary. Tyrosine is an essential amino acid in premature infants. It is metabolized from Phenylalanine and can be metabolized to Cystine. It functions synergistic with folic acid, copper and Vitamin C. It should not be taken as a supplement when taking MAO (monoamineoxidase) drugs.

Alanine is produced during carbohydrate metabolism. It is a source of energy for the muscles, brain and central nervous system (CNS). It takes part in the metabolism of glucose, Vitamin B6 and tryptophan and helps strengthen the immune system. Isoleucine stimulates the release of alanine from muscle tissues. Alanine inhibits taurine transport. When alanine, arginine and glycine are administered together, there is some evidence of cholesterol reduction.

Asparatic acid is synthesized from glutamate. It aids in the expulsion of ammonia via the urea cycle, thus increasing the resistance to fatigue and increasing endurance. Asparatic acid also, via the Krebs cycle, is involved in the metabolism of carbohydrates. Asparatic acid plays a part in brain neurotransmitters and perhaps in the thymus gland. It is synergistic with Vitamin B6, zinc, magnesium and potassium.

Citrulline is involved in the detoxification and elimination of ammonia, that is it functions in the urea cycle. Ornithine is its precursor and citrulline in its turn, can be metabolized to Arginine.

Cysteine, like methionine, contains a sulfur group. Cysteine is required for the formation of glutathione, coenzyme A, insulin, heparin, biotin, lipoic acid and enzymes with sulhydryl (-SH groups), such as monoamineoxidases (MAO). Cysteine is involved a brain neurotransmitter chemistry. It can be oxidized to cystine. Cysteine is syngergistic with Vitamin B6 and C. It is a very useful antioxidant. However, it is very soluble and easily eliminated in the urine.

GABA - Gamma-Aminobutyric Acid
This is a non-essential amino acid formed from glutamic acid. Vitamine B6 (pyridoxine) is a cofactor in the production of GABA in the brain, whereas, manganese, taurine and lysine can increase both the synthesis and effects of GABA.

GABA is the most widely distributed inhibitory neurotransmitter in the brain and drugs such as Valium, Librium and Xanax, mimic GABA, by attaching themselves to the same sensitive neurons and receptors in the brain as GABA does. GABA can play a part in the control of seizure disorders and is also involved in the proper functioning of the thymus, duodenum and pancreas.

In addition, research has shown that GABA is involved in the control mechanism of high blood pressure and orally given GABA can sometimes lower blood pressure.

GABA itself is not found in foods, but glutamic acid its precursor, is high in wheat gluten, wheat germ, cottage and ricotta cheese and meats. Fruits and most cereals are low in glutamic acid.

Doses of GABA supplement that have been used varied from 50mg to 500mg given up to 3 times per day, BUT TOTAL DOSES OF MORE THAN 3000mg PER DAY MAY PRODUCE ADVERSE EFFECTS.

Glutamic acid is very highly concentrated in the brain, where it is an excitory neurotransmitter. In the body it can be formed from aspartic acid, ornithine, arginine and proline. In the body it is converted into glutamine and GABA (gamma-aminobutyric acid). Glutamate is poorly transported from the blood to the brain, but easily transferred from the brain to the blood. Glutamic acid is synergistic with Vitamins B6, C and manganese. It is useful in the combat of fatigue and in the control of alcoholism, craving for sugar and in some forms of schizophrenia. In excess it is neurotoxic.

It is important in the urea cycle. Along with methionine it is involved in many processes related to cell proliferation. It is a precursor of citrulline, Glutamic acid and Proline. In some processes it is interchangeable with Arginine. Ornithine has an ability to enhance liver function. Lysine can, under some circumstances, inhibit Ornithine metabolism

Proline is synthesized in the body from L-glutamate or L-ornithine. Dietary proline is a precursor to collagen hydroxyproline. Thus, proline is involved in the functioning of the joints, tendons and heart muscles. Proline functions synergistically with Vitamins B6, B3 and C.

Serine is derived from glycine and it can also be converted to glycine. Serine can be metabolized into choline and phospholipids. It is important in the sheaths around nerve fibers. Serine is also important in the production of glucose. Serine functions with folic acid, methionine and Vitamins B6 and B3. Home Page

NOTE: All information on this page is copyrighted by RosettaStoneInc, and may not be duplicated

email Dr. Inge Harding-Barlow