Well, there may be more or less than 20 on this list, but that's ok.
Alanine
It is required for the metabolism of glucose and tryptophan and beta-alanine is a constituent of vitamin B5 (pantothenic acid) as well as coenzyme A. It has also demonstrated a cholesterol-reducing effect in rats.
People suffering from Epstein Barr (also sometimes referred to as glandular fever) as well as chronic fatigue syndrome, have been linked to excessively high levels of alanine while having low levels of tyrosine and phenylalanine.
Deficiency of alanine
None known.
Dosage
Dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Most people do not need to supplement with alanine since it is well provided for in the diet, and can be synthesized from pyruvic acid (formed in the breakdown of carbohydrates).
Toxicity and symptoms of high intake
Alanine does not have many side effects, but people with kidney or liver disease should not consume high intakes of amino acids without consulting a health care professional.
When more may be required
People on a very low protein diet, could be at risk of a deficiency.
Other interesting points
It has been found that alanine is present in prostate fluid, and it may play a role in the role of the prostate. In one study of men with benign prostatic hyperplasia, it was found that 780 mg of alanine per day for two weeks and then 390 mg for the next two and a half months, taken together in combination with equal amounts of glycine and glutamic acid reduced the symptoms.
Food sources of alanine
As with the other amino acids, excellent sources of alanine include meat, poultry, fish, eggs, and dairy products. Some protein-rich plant foods like avocado also supply alanine.
Arginine
It is extremely useful in enhancing the immune system, and it increases the size and activity of the thymus gland, which is responsible for manufacturing T lymphocytes – the much talked about T-cells, which assist the immune system. For this reason it might be an important nutrient for people suffering from AIDS and other malignant diseases which suppress the immune system.
In the pancreas it is used to release insulin and in the pituitary gland it is a component of human growth hormone, and is used in sexual stimulants, as people report longer and more intense orgasms when their intake of arginine is increased.
It is also important in liver health and assists in neutralizing ammonia in the liver, while it is also involved in the skin and connective tissue – making it important in healing and repair of tissue as well as the formation of collagen and building of new bone and tendons.
Arginine is found in seminal fluid and L-arginine is used in the treatment of male sexual health and has been used in the treatment of sterility.
It is required in muscle metabolism – maintaining the nitrogen balance, and helping with weight control since it facilitates the increase of muscle mass, while reducing body fat.
Deficiency of arginine
Rare – but signs may include impaired insulin production as well as possible hair loss.
Dosage
Dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Toxicity and symptoms of high intake
Rare, but symptoms of massive dosages may include skin thickening and coarsening of the skin, weakness, diarrhea, nausea, as well as increasing the activity of some viruses. For this reason people suffering from herpes should avoid high dosage. Pregnant and lactating women and people suffering from schizophrenia should also avoid high dosage.
Other interesting points
Arginine pyroglutamate, in addition to having cognitive enhancing effects, is an excellent growth hormone releaser because it is carried more efficiently across the blood-brain barrier than arginine alone. In Italy, this form of amino acid is used to treat senility, mental retardation, and alcoholism. Arginine pyroglutamate is an arginine molecule combined with a pyroglutamate molecule. Arginine alone does not produce cognitive enhancing effects.
This nutrient is gaining popularity as a non-prescription treatment for high cholesterol as animal studies and preliminary studies in humans suggest that it may improve coronary blood flow and lower cholesterol levels with its antioxidant property, and helping to keep blood-vessel tissue elastic.
Food sources of arginine
Whole-wheat, nuts, seeds, peanuts, brown rice, popcorn, soy, raisins, chocolate, carob.
Aspartic Acid
It is of paramount importance in the metabolism during construction of other amino acids and biochemicals in the citric acid cycle. Among the biochemicals that are synthesized from aspartic acid are asparagine, arginine, lysine, methionine, threonine, isoleucine, and several nucleotides.
It is needed for
stamina, brain and neural health and assists the liver by removing excess ammonia and other toxins from the bloodstream. It is also very important in the functioning of RNA, DNA, as well as the production of immunoglobulin and antibody synthesis.
Deficiency of aspartic acid
Symptoms may include fatigue and depression.
Dosage
Dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Food sources of aspartic acid
It is found in dairy, beef, poultry, sprouting seeds
Cysteine
Your skin, as well as detoxification of your body, requires cysteine. It is found in beta-keratin, the main protein in nails, skin as well as hair. It not only is important in collagen production but also assists in skin elasticity and texture.
Cysteine is also required in the manufacture of the amino acid taurine and is a component of the antioxidant gluthione. It is useful to detoxify the body from harmful toxins and help protect the brain and liver from damage from alcohol, drugs etc.
It has also been found that it may help in strengthening the protective lining of the stomach as well as intestines, which may help prevent damage caused by aspirin and similar drugs.
Cysteine is also critical to the metabolism of a number of essential biochemicals including coenzyme A, heparin, biotin, lipoid acid, and glutathione.
Deficiency of cysteine
No direct deficiencies have been reported as such.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
General dosage is not known but as supplement cysteine is used at 200 mg two to three times per day.
Toxicity and symptoms of high intake
None known, but damage to nerve cells in rats has been reported in very high dosage, and research data is still being waited upon.
People suffering from diabetes and cystinuria should be careful of cysteine supplements.
Best used with
Best taken with selenium vitamin B6 and vitamin E.
When more may be required
People suffering from AIDS/HIV may benefit from cysteine in proper amounts, as low levels are normally reported in people with this problem.
Food sources of cysteine
The body can synthesize cysteine from the amino acid methionine but is also found in high protein foods such as poultry, wheat, broccoli, eggs as well as garlic, onions and red peppers.
GABA
GABA is required as an inhibitory neurotransmitter to block the transmission of an impulse from one cell to another in the central nervous system, which prevents over-firing of the nerve cells.
It is also used for brain metabolism and to treat both epilepsy and hypertension where it is thought to induce tranquility in individuals who have a high activity of manic behavior and acute agitation.
In combination with inositol and nicotinamide it helps with blocking anxiety and stress related impulses from reaching the motor centers of the brain.
Gamma-Aminobutyric Acid can be used to calm a person, much like tranquilizers, but without the possibility of addiction.
Deficiency of GABA
It has been suggested that a shortage of GABA may cause panic attacks, since an intake of tranquilizers can increase the level of GABA in the body. GABA may also be effective in treating PMS in women.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Dosage has not been established, but it is interesting to note that some research suggests that the supplement Kava (kava is a herbal root used as a supplement) causes more GABA receptors to form in the brain.
Toxicity and symptoms of high intake
Toxic levels have not been established, but very high intake of GABA may cause anxiety, tingling of extremities, shortness of breath as well as a numb feeling around the mouth.
Other interesting points
It is sometimes used as sexual a stimulant because of its relaxing capabilities, as well as with prostate problems, since it also assists with the release of sex hormones.
Glutamic Acid
It is an important excitatory neurotransmitter, and glutamic acid is also important in the metabolism of sugars and fats.
It helps with the transportation of potassium across the blood-brain barrier, although itself does not pass this barrier that easily. It also shows promise in the future treatment of neurological conditions, ulcers, hypoglycemic come, muscular dystrophy, epilepsy, Parkinson's, and mental retardation.
Glutamic acid can be used as fuel in the brain, and can attach itself to nitrogen atoms in the process of forming glutamine, and this action also detoxifies the body of ammonia. This action is the only way in which the brain can be detoxified from ammonia.
The fluid produced by the prostate gland also contains amounts of glutamic acid, and may play a role in the normal function of the prostate.
Deficiency of glutamic acid
None known.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Toxicity and symptoms of high intake
High dosages of glutamic acid may include symptoms such as headaches and neurological problems.
Although no major side effects are reported on supplementation of this nutrient, people with kidney or liver disease should not consume high intakes of amino acids without first consulting a medical professional.
People suffering from personality disorders as well as child behavior disorders may find benefit from this nutrient.
Food sources of glutamic acid
Excellent sources of glutamic acid include meat, poultry, fish, eggs, and dairy products, as well as some protein-rich plant foods.
Glutamine
It is converted to glutamic acid in the brain, which is essential for cerebral functions, and increases the amount of GABA (gamma-aminobutyric acid), which is required for brain functioning and mental activity.
It is used in the muscles for the synthesis of muscle proteins, and is of use for the treatment of wasting muscles after illness or post-operative care.
Although the body requires nitrogen, free nitrogen in the body can be harmful since it forms ammonia – especially toxic to the brain. The liver normally converts ammonia to urea, excreted in the urine – but glutamic acid attaches itself to nitrogen and forms glutamic acid, while removing ammonia from the brain.
It further is used in the body to balance the acid/alkaline level and is also the basis or building blocks of RNA and DNA.
It serves as a source of fuel for cells lining the intestines and it is also used by white blood cells and is important for immune function.
Deficiency of glutamine
Deficiency of this nutrient is rare, since it can be manufactured by the body but deficiencies can develop during periods of fasting, starvation, strict dieting, cirrhosis, and weight loss associated with AIDS and cancer.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
In the presence of good health, supplementation of glutamine should not be necessary.
Toxicity and symptoms of high intake
No clear toxicity has emerged in glutamine studies, but it should not be taken by people suffering from liver or kidney problems.
When more may be required
People suffering from arthritis, fibrosis, connective tissue disease, peptic ulcers, ulcerative colitis, as well as epilepsy, fatigue, impotence and senility may find benefit from an increase of this nutrient, as well as people busy with alcohol abuse withdrawal and patients living with HIV.
Other interesting points
Monosodium glutamate (MSG), a salt of glutamic acid, is sometimes used as a condiment for flavoring foods. It imparts no flavor of its own, but enhances the flavors of meats, fish, and vegetables. Some people have an allergic reaction to MSGs, and should be avoided by such individuals.
L-glutamine supplements are also referred to as “smart drugs” since it is thought to improve the functioning of the brain.
In animal research, glutamine has anti-inflammatory effects. Glutamine also decreases the craving for sweets and sugar, which is beneficial to people wishing to lose weight.
Food sources
Glutamine is found in many high protein foods, such as fish, meat, beans, and dairy as well as in vegetables such as raw parsley and spinach.
Glycine
It is required to build protein in the body and synthesis of nucleic acids, the construction of RNA as well as DNA, bile acids and other amino acids in the body. It is further found to be useful in aiding the absorption of calcium in the body.
It helps in retarding degeneration of muscles since it helps to supply extra creatine in the body.
It is also found in fairly large amounts in the prostate fluid and may for this reason be important in prostate health.
The glycine amino acid is also used by the nervous system and its function as an inhibitory neurotransmitter makes it important to help prevent epileptic seizures and it is also used in the treatment of manic depression and hyperactivity.
Deficiency of glycine
Few people are glycine deficient, in part because the body makes its own supply of the non-essential amino acids, and because it is abundant in food sources.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Toxicity and symptoms of high intake
No clear toxicity has emerged from glycine studies, however individuals with kidney or liver disease should not consume high intakes of amino acids without consulting a health care professional.
When more may be required
In a study where men were given extra glycine over a period of time, it reduced the symptoms of prostatic hyperplasia.
Other interesting points
If the amino acid serine is required in the body, it can be converted from glycine.
Food sources of glycine
High protein food contains good amounts of glycine and is present in fish, meat, beans, and dairy products.
Histidine
Histidine is also a precursor of histamine, a compound released by immune system cells during an allergic reaction.
It is needed for growth and for the repair of tissue, as well as the maintenance of the myelin sheaths that act as protector for nerve cells.
It is further required for the manufacture of both red and white blood cells, and helps to protect the body from damage caused by radiation and in removing heavy metals from the body.
In the stomach, histidine is also helpful in producing gastric juices, and people with a shortage of gastric juices or suffering from indigestion, may also benefit from this nutrient.
Deficiency of histidine
None known, but it is reported that an increase in the intake of this nutrient helps with the lengthening of orgasms and also more intense sexual enjoyment.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Some people take 1,000 mg of histidine two to three times per day in capsule or tablet form but it is best to work out the dosage requirements as 8-10 mg per day per kilogram of body weight.
Toxicity and symptoms of high intake
There are no reported side effects with histidine, but too high levels of histidine may lead to stress and mental disorders such as anxiety and people with schizophrenia have been found to have high levels of histidine.
People suffering from schizophrenia or bipolar (manic) depression should not take a histidine supplement without the approval of their medical professional.
Best used with
Best taken with vitamin B3 (niacin) and B6 (pyridoxine).
When more may be required
Although not conclusively proven – it is thought that histidine may be beneficial to people suffering from arthritis and nerve deafness.
Other interesting points
Histidine is also used for sexual arousal, functioning and enjoyment
Histidinemia is an inborn error of the metabolism of histidine due to a deficiency of the enzyme histidase, where high levels of histidine are found in the blood and urine, and may manifest in speech disorders and mental retardation.
Food sources of histidine
Dairy, meat, poultry and fish are good sources of histidine as well as rice, wheat and rye.
Isoleucine
Isoleucine, together with the other two branched-chain-amino-acids promote muscle recovery after physical exercise and on its own it is needed for the formation of hemoglobin as well as assisting with regulation of blood sugar levels as well as energy levels. It is also involved in blood-clot formation.
Deficiency of isoleucine
Deficiency of isoleucine is only found in people deficient in dietary protein but symptoms may include headaches, dizziness, fatigue, depression, confusion as well as irritability. Symptoms of deficiency may mimic the symptoms of hypoglycemia. This nutrient has also been found to be deficient in people with mental and physical disorders, but more research is required on this.
Also see leucine and valine, and look at branched-chain amino acids.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
Most people ingest enough isoleucine from their diet, although some individuals do supplement their diet with about 650 - 700 mg of isoleucine per day (based on a 70 kg body), or worked out to 10 - 12 mg per kg of body weight per day.
If you are taking a supplement of isoleucine, keep it in balance with the other two branched-chain-amino-acids leucine and valine in the formula of 2 mg of leucine and valine for each 1 mg of isoleucine.
Toxicity and symptoms of high intake
Consuming higher amounts of isoleucine is not associated with any health risks for most people but those with kidney or liver disease should not consume high intakes of amino acids without medical advise.
People ingesting higher amounts of isoleucine report elevated urination.
When more may be required
People involved with strenuous athletic activity under extreme pressure and high altitude may benefit from supplementation of this nutrient.
Food sources of isoleucine
It is present in almonds, cashews, chicken, eggs, fish, lentils, liver, meat etc.
Leucine
Leucine helps with the regulation of blood-sugar levels, the growth and repair of muscle tissue (such as bones, skin and muscles), growth hormone production, wound healing as well as energy regulation. It can assist to prevent the breakdown of muscle proteins that sometimes occur after trauma or severe stress. It may also be beneficial for individuals with phenylketonuria - a condition in which the body cannot metabolize the amino acid phenylalanine
Deficiency of leucine
Deficiency of this nutrient is rare, since all protein foods contains it, but vegans and vegetarians without adequate protein sources may suffer from a deficiency. Hypoglycemia symptoms may appear if the diet is deficient and may include dizziness, fatigue, headaches, irritability etc.
Also see isoleucine and valine, and look at branched-chain amino acids.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
The daily dosage of leucine is about 16 mg per kilogram of body weight per day - which would translate to about 1120 mg for a 70 kg male. See good combinations as well.
Toxicity and symptoms of high intake
Consistent evidence of toxicity has not been linked to leucine supplements.
A high intake of leucine could contribute to pellagra as well as increase the amount of ammonia present in the body.
Best used with
If you are taking a supplement of leucine, keep it in balance with the other two branched-chain-amino-acids isoleucine and valine in the formula of 2 mg of leucine and valine for each 1 mg of isoleucine.
Food sources of leucine
It is found in protein foods, as well as brown rice, beans, nuts and whole wheat.
Lysine
It is required for growth and bone development in children, assists in calcium absorption and maintaining the correct nitrogen balance in the body and maintaining lean body mass. Furthermore it is needed to produce antibodies, hormones, enzymes, collagen formation as well as repair of tissue.
Since it helps with the building of muscle protein, it is useful for patients recovering from injuries and recovery after operations, and there might be use in lysine to help maintain healthy blood vessels. It also seems to assist in fighting herpes and cold sores.
Deficiency of lysine
Although a deficiency of lysine is rare, since it is found in so many protein foods, the symptoms may include anemia, enzyme disorders, lack of energy, hair loss, bloodshot eyes, weight loss and retarded growth as well as reproductive problems, poor appetite and poor concentration.
People on a vegan or vegetarian diet, using grains as their only source of protein are often deficient in this nutrient.
Dosage
The dosage listed is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
The daily dosage of lysine is about 12 mg per kilogram of body weight per day - which would translate to about 840 mg for a 70 kg male.
Pregnant or breast feeding mothers, as well as patients with liver or kidney problems, must first consult a health professional before taking lysine supplements.
Toxicity and symptoms of high intake
Toxicity has not been determined but animals fed high amounts of lysine, have shown a tendency to gallstones as well as elevated cholesterol - but these tendencies have not been proven in humans.
Diarrhea and stomach cramps may be indicative in high dosage, but these are not consistent symptoms.
When more may be required
Athletes, burn patients and people suffering from herpes and cold sores may benefit from an increase of lysine.
Older people could also require more lysine, as one study found older men required more of this nutrient than younger men.
Other interesting points
Lysine must be used with care in supplement form when taking antibiotics as well.
Food sources of lysine
Good sources of lysine are found in cheese, eggs, lime beans, potatoes, milk, meat and brewer's yeast.
Methionine
It assists in the breakdown of fats and thereby prevents the build-up of fat in the arteries, as well as assisting with the digestive system and removing heavy metals from the body since it can be converted to cysteine, which is a precursor to gluthione, which is of prime importance in detoxifying the liver.
The amino acid methionine is also a great antioxidant as the sulfur it supplies inactivates free radicals. It may also be used to treat depression, arthritis pain as well as chronic liver disease - although these claims are still under investigation. Some studies have also indicated that methionine might improve memory recall.
It is also one of the three amino acids needed by the body to manufacture creatine monohydrate, a compound essential for energy production and muscle building.
Deficiency of methionine
Severe deficiency may manifest in dementia, while lesser deficiencies may be known by symptoms like fatty liver, slow growth, weakness, edema and skin lesions.
Dosage
The dosage listed underneath is the Recommended Daily Allowance (RDA), but be aware that this dosage is the minimum that you require per day, to ward off serious deficiency of this particular nutrient. In the therapeutic use of this nutrient, the dosage is usually increased considerably, but the toxicity level must be kept in mind.
The daily dosage of leucine is about 12 mg per kilogram of body weight per day - which would translate to about 840 mg for a 70 kg male.
Toxicity and symptoms of high intake
It has been suggested that a high intake of methionine, in the presence of B vitamin deficiencies, may increase the risk for arteriosclerosis (hardening of the arteries) by increasing blood levels of cholesterol and a compound called homocysteine; and that excessive methionine intake, with an inadequate intake of folic acid, vitamin B6 and vitamin B12, may increase the rate of conversion of methionine to homocysteine - both these theories have not been proven in humans.
Best used with
If you are considering taking a methionine supplement, it is best to balance it with choline and inositol.
When more may be required
People with liver problems, pancreatitis, HIV/AIDS as well as Parkinson's disease may consider obtaining more methionine, after consultation with their health professional, and older people may also benefit from a slightly higher intake of this nutrient.
Women on birth control pills could also look at this nutrient, since it promotes the excretion of estrogen. People suffering from schizophrenia could investigate taking extra methionine since it reduces the level of histidine in the body, a level normally higher in people suffering from schizophrenia.
Food sources
Methionine is found in good quantities in meat, fish, beans, eggs, garlic, lentils, onions, yogurt and seeds.
