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Amino Acid Deficiencies and Imbalances
Definition
Amino acids are building blocks from which proteins are made as well as the end product of protein
digestion. The proper combination of amino acids is necessary for protein synthesis, and protein is vital to
the structure of all living things. Essential amino acids are amino acids that cannot be synthesized by the
body and must be acquired by the diet. They include isoleucine, leucine, lysine, methionine, phenylalanine,
threonine, tryptophan and valine. Two amino acids, arginine and histidine, are considered to be semi-
essential or conditionally essential amino acids. They are needed in increased amounts during pregnancy
and for children during their growth years.
The non-essential amino acids include alanine, asparagine, aspartic acid, cysteine (2 cysteine molecules can
bind to form a new amino acid called cystine), glutamic acid, glutamine (also considered to be a conditionally
essential amino acid), glycine, proline, serine and tyrosine. The non-essential amino acids are manufactured
by the body to build important proteins, such as hormones, hemoglobin, enzymes and antibodies. Taurine is
a non-essential sulfur-containing amino acid-like compound that is synthesized from methionine and cysteine
in the presence of vitamin B-6. Taurine is the most abundant intracellular amino acid in humans.
Clinical Applications/Research
Amino acids will always be an integral part of nutritional support in all patients. The use of specific amino
acids in pharmacologic doses may be beneficial to critically ill patients, indicating that such compounds are
conditionally essential (Surg Clin North Am 1991;71(3):459-76). The amino acid histidine is found in parsley,
and has been found to be a strong inhibitor of tumor development (Mutation Research 77:245-50, as cited in
(Heinerman, J. Heinerman’s Enc. of Fruits, Vegetables and Herbs. 1988. Parker Publ. West Nyack, NY p.
260).
"Arginine, glutamine, the long chain polyunsaturated omega-3 and omega-6 fatty acids, and, to a lesser
extent, ribonucleic acid and the vitamins E, C, and A have pharmacological effects when given in amounts in
excess of what is needed to prevent nutritional deficiency. These effects are exerted primarily via the
immune system. Immune enhancing diets that embody the recently developed principles of nutritional
pharmacology have been shown to reduce infectious complications by approximately 75% in surgical patients
and hospital stay by more than 20% in surgical patients and patients in the intensive care unit in three
independent, prospective, randomized studies, two of which were double-blinded. These findings suggest
that specialized diets can be designed that will be of benefit to patients with cancer, atherosclerosis, intestinal
diseases, autoimmune diseases, infections, and trauma" (Arch Surg 1993;128(11):1242-5).]
Essential Amino Acids
- LEUCINE, ISOLEUCINE, VALINE
Description
The branched-chain amino acids (BCAAs) include leucine, isoleucine and valine. BCAAs are essential amino acids that are needed for building and maintaining muscle tissue, during times of physical stress and intense exercise. The BCAAs are sometimes referred to as the "stress amino acids" because they are used up more rapidly during times of intense stress.
Sources
Dairy, red meat, whey protein, and egg protein
Dosage
Athletes in intense training -- 5 grams leucine plus 4 grams valine plus 2 grams isoleucine daily.
Side Effects
None reported.
How to Take
Take branched-chain amino acids with whole, complete proteins (animal sources), and a high-potency vitamin-mineral including a B-complex.
Clinical Applications
See individual amino acid in "Vitamins, Minerals and Specialty Nutrients" section for more information.
- LYSINE
Description
Lysine is an essential amino acid. Lysine helps the body absorb and conserve calcium and may help support blood vessel integrity. Lysine is a precursor to carnitine and citrulline. Lysine contributes to the synthesis of connective tissue, brain neurotransmitters and carbohydrate metabolism as a precursor to acetyl CoA. Lysine is metabolized with the help of vitamins B-2 and B-3.
Sources
Brewer’s yeast, dairy, wheat germ, fish, meat, eggs, poultry, cheese, lima beans, and shrimp
Dosage
Maintenance Dosage: 500 to 1,000 mg daily; Therapeutic Dosage: 1 to 6 grams daily.
Toxicity
Inborn errors of metabolism can lead to an elevation of lysine. High levels of lysine can result in mental retardation, delayed sex development, facial bone abnormalities, enlarged liver, and obesity.
- METHIONINE
Description
Methionine is an essential sulfur-containing amino acid. Methionine acts as a lipotropic factor, mobilizing the movement of fat through the liver to prevent accumulation. Methionine is needed to synthesize creatine monohydrate, a compound essential for energy production and muscle function. Methionine is incorporated into S-adenosyl methionine (SAM). SAM is an important biochemical methylating agent. SAM contributes to the synthesis of brain neurotransmitters and to detoxification reactions. SAM also has analgesic properties. Methionine serves as a sulfur donor, a methyl donor, a precursor for other sulfur amino acids, and a metabolizing agent for polyamines.
Sources
Meat, egg yolks, wheat germ, ricotta cheese, and sunflower seeds
Dosage
Maintenance Dosage: 800-1,000 mg of methionine daily (readily available in the average American diet); Therapeutic Dosage: 1 to 3 grams daily.
Toxicity
High methionine intake, with B vitamin deficiencies, may increase the risk for atherosclerosis by increasing blood levels of cholesterol and homocysteine. Excessive methionine intake, with inadequate intake of folic acid, vitamin B-6 and vitamin B-12, may increase homocysteine. Nausea and gastrointestinal irritation are signs of rarely-occurring methionine toxicity. Caution is indicated in bipolar patients because SAM may precipitate the manic phase. It is unclear if SAM has the same problems with elevated levels of homocysteine as methionine does. In cases of a strong family history of coronary heart disease, it is wise to check homocysteine levels before and during treatment.
- PHENYLALANINE
Description
L- phenylalanine is an essential amino acid. L-phenylalanine can be converted in the body into the amino acid L-tyrosine, which can be converted into L-dopa, norepinephrine, and epinephrine, three compounds critical to nervous system functioning. L-phenylalanine can also be converted, via a different biochemical pathway, into phenylethylamine, a brain compound that elevates mood. D-phenylalanine is not normally found in the body. When supplemented, it is converted predominantly into phenylethylamine (PEA), which also can elevate mood. D-phenylalanine influences brain biochemical pathways linked to pain sensation by inhibiting enzymes that break down enkephalins and endorphins that reduce pain. DLPA is a racemic mixture of L-phenylalanine and D-phenylalanine. DLPA has been used to treat depression. D-phenylalanine may be helpful for Parkinson’s disease and chronic pain (osteoarthritis and rheumatoid arthritis). DLPA can be used as a substitute for the D-form, as it contains 50% D-phenylalanine.
Sources
L-form - food
D-form - DLPA supplements
Dosage
L-form: 1 gram daily.
Depression: 1 to 6 grams daily DLPA.
Pain: 756-1,500 mg daily DLPA.
Parkinson’s: 750 mg three times daily of the L-form may help rigidity and depression, but not tremors.
Toxicity
Powerful effects on mood and the nervous system require close medical supervision. Large quantities of individual amino acids can cause nerve damage. Nerve damage has not been reported at 1,500 mg daily or less of DLPA. Mild side effects, such as nausea, heartburn, or transient headaches, have been reported at recommended doses. People with phenylketonuria must not supplement with phenylalanine.
- TRYPTOPHAN
Description
Tryptophan is an essential amino acid that is actively transported into the brain. Tryptophan competes with tyrosine, phenylalanine, valine, leucine and isoleucine for transport into the brain. Tryptophan is usually given with vitamin B-6 away from meals with a small amount of carbohydrate to facilitate uptake by the brain. Tryptophan is metabolized into niacin, serotonin, and melatonin. Major functions of tryptophan include:
- Precursor to serotonin and melatonin
- Substrate for cerebral biochemical functions
- Precursor to niacin
Sources
Fish, meat, dairy, eggs, nuts, and wheat germ
- Least abundant amino acid in foods.
- Low in most dietary proteins.
- Corn is particularly low. The small amount is more available if treated with lime.
Dosage
Relative to other amino acids, only small amounts are required to have a therapeutic effect.
- 0.5 to 4 grams daily, short term.
- Co-factors for metabolism: Vitamins B-3, B-6, and C.
- High carbohydrate/low protein food to enhance brain uptake.
- Foods with pre-formed serotonin may help uptake: bananas, walnuts, pineapples.
Toxicity
Low toxicity. 100 mg/kg/day can cause gastrointestinal upset and head twitching. Tryptophan may be teratogenic at 8 grams per day. Caution is advised during pregnancy. In women, 5-hydroxytryptophan (5HTP) may have fewer side effects. Foods containing tryptophan are carcinogenic to breast and bladder tissues when charbroiled or heated to high temperatures. Contraindications include female infertility, pregnancy, rheumatoid arthritis, cataracts, and psoriasis. Long-term supplementation increases plasma levels of other amino acids. This effect may be beneficial. Antidepressant pharmaceutical effects may be amplified. Tyrosine, phenylalanine, valine, leucine and isoleucine compete with tryptophan for transport into the brain.
- ARGININE
Description
Arginine is an amino acid that has many functions in the body. Arginine is essential for birds and is conditionally essential to most mammals and to humans. It is synthesized in the body from glutamic acid.
Sources
Meat, eggs, milk, cheese and nuts
Dosage
4 - 6 grams daily.
Toxicity
Herpes simplex: Arginine promotes the growth of Herpes simplex, especially if lysine levels are low. Excessive arginine (over 40 grams daily) may cause diarrhea. High serum cholesterol can be induced by arginine in patients with severe liver disease and kidney disorders.
- GLUTAMINE
Description
Glutamine is a conditionally essential amino acid that is synthesized from glutamic acid. Glutamine is the most abundant amino acid in skeleton, muscle and blood. Glutamine is 10 to 15 times more concentrated in the brain than in the blood. Glutamine is the preferred nutrient for mucosal cells of the stomach and small intestine (with alanine). Glutamine is also the preferred amino acid nutrient in the brain, involved in neurotransmitter biochemistry. Glutamine is essential during excessive stress - injury, septicemia, burns, and inflammatory bowel disease. Glutamine is needed by rapidly dividing cells - lymphocytes, macrophages, and thymocytes. Glutamine is involved with acid-base balance in the body and is essential for synthesis of vitamin B-3 within the body. Glutamine is also essential for the metabolism of uric acid and arginine. Glutamine promotes, in combination with N-acetyl cysteine, the synthesis of glutathione, a naturally occurring antioxidant.
Sources
Fish, meat, beans, and dairy
Dosage
5 to 12 grams daily.
Toxicity
None reported.
- HISTIDINE
Description
Histidine is a semi-essential amino acid. People produce adequate amounts except during periods of growth. Histidine is a precursor to histamine, a compound released by mast cells of mucous membranes during allergic reactions and the central nervous system during a migraine.
Sources
Meat, poultry, fish, and dairy
Dosage
1,000 mg two to three times daily
Toxicity
None reported.
- ASPARAGINE
Description
Asparagine is a non-essential amino acid that is synthesized from aspartate and glutamine. Asparagine is a required precursor for the synthesis of RNA, DNA and ATP (energy).
Sources
Milk protein and meats
- CYSTEINE
Description
Cysteine is a non-essential amino acid. Cysteine contains sulfur, which allows cysteine to help maintain the structure of proteins in the body. Cysteine is one of three amino acid components of the antioxidant glutathione, used by the liver to detoxify chemical toxins and waste compounds. Cysteine is used by the body to synthesize the amino acid taurine.
Sources
The body can synthesize cysteine from methionine. Cysteine is found in most high-protein foods.
Dosage
200 mg two to four times daily.
Toxicity
Daily amounts of 1.2 grams or more may lead to oxidative damage. Very large amounts have been toxic to nerve cells in rats.
- GLUTAMIC ACID
Description
Glutamic acid is a non-essential amino acid that the body uses to build proteins. Glutamic acid is structurally distinct from glutamine.
Sources
Meat, poultry, fish, eggs, and dairy
Dosage
For BPH -- 780 mg daily for two weeks and then 390 mg daily thereafter in combination with equal amounts of alanine and glycine.
Toxicity
Glutamic acid is free of side effects for most people. Persons with kidney or liver disease should not consume high amounts of amino acids without careful supervision.
- GLYCINE
Description
Glycine is a non-essential amino acid that is found abundantly in prostate fluid. Glycine may play a role in prostate health, in combination with alanine and glutamic acid.
Sources
Fish, meat, beans, and dairy
Dosage
BPH -- 780 mg daily for two weeks and then 390 mg daily, in combination with equal amounts of alanine and glutamic acid.
Toxicity
None reported. Persons with kidney or liver disease should be monitored carefully.
- TAURINE
Description
Taurine is a non-essential sulfur-containing amino acid that is synthesized from methionine and cysteine in the presence of vitamin B-6. Taurine is the most abundant intracellular amino acid in humans.
Sources
Animal and fish protein, especially organ meats, such as brains
Dosage
1.5 to 6 grams daily.
Toxicity
Taurine supplementation may contribute to ulcers in a patient taking aspirin concurrently.
- TYROSINE
Description
Tyrosine is a non-essential amino acid synthesized in the body from phenylalanine. Tyrosine supports the structure of almost all proteins in the body. Tyrosine is the precursor of the neurotransmitters L-dopa, dopamine, norepinephrine, and epinephrine. Tyrosine supports the synthesis of enkephalins, which have pain-relieving effects. It is the precursor to melanin pigment
in skin cells and a substrate for the synthesis of thyroid hormones.
The genetic condition phenylketonuria (PKU) obstructs the metabolizing of the amino acid phenylalanine. This state results in low tyrosine levels in many (but not all) PKU patients. Tyrosine supplementation may be beneficial in some people with PKU, although the evidence remains preliminary.
Sources
Dairy, meats, fish, wheat, and oats
Dosage
- 1 to 10 grams daily.
- 100 mg/kg body weight per day.
- Start with 2 grams per day and work up.
- Use short term.
- Vitamins B-3, B-6, and C; folic acid; and copper are needed for conversion of tyrosine into neurotransmitters.
Toxicity
Tyrosine has a very low toxicity. Very high intake may cause diarrhea, nausea, vomiting, or nervousness. Caution is indicated with concurrent antidepressant drugs. Theoretically, a hypertensive crisis is possible.
Copyright 1998-2004 HealthQuest, Inc.
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