Taurine
Encyclopedia
Taurine, or 2-aminoethanesulfonic acid, is an organic acid
widely distributed in animal tissues. It is a major constituent of bile
and can be found in the large intestine
and accounts for approximately 0.1% of total human body weight. Taurine has many fundamental biological roles such as conjugation of bile acid
s, antioxidation
, osmoregulation
, membrane stabilization
and modulation of calcium signaling
. It is essential for cardiovascular
function, and development and function of skeletal muscle
, the retina
and the central nervous system
. Taurine is unusual among biological molecules in being a sulfonic acid
, while the vast majority of biologically occurring acids contain the more weakly acidic carboxyl group. While taurine is sometimes called an amino acid, and indeed is an acid
containing an amino group, it is not an amino acid
in the usual biochemical meaning of the term, which refers to compounds containing both an amino and a carboxyl group.
of the Greek ταύρος) which means bull or ox, as it was first isolated from ox
bile in 1827 by German scientists Friedrich Tiedemann
and Leopold Gmelin
.
, an amino acid which contains a sulfhydryl
group. Taurine is one of the few known naturally occurring sulfonic acid
s. In the strict sense, it is not an amino acid, as it lacks a carboxyl group
, but it is often called one, even in scientific literature. It does contain a sulfonate group
and may be called an amino sulfonic acid. Small polypeptides have been identified which contain taurine, but to date no aminoacyl tRNA synthetase
has been identified as specifically recognizing taurine and capable of incorporating it into a tRNA
.
is first oxidized to cysteine sulfinic acid by the enzyme cysteine dioxygenase
. Cysteine sulfinic acid, in turn, is decarboxylated by sulfinoalanine decarboxylase
to form hypotaurine
. It is unclear whether hypotaurine is then spontaneously or enzymatically oxidized to yield taurine.
s. In addition, it has been shown to be effective in removing fatty liver deposits in rats, preventing liver disease, and reducing cirrhosis
in tested animals. There is also evidence that taurine is beneficial for adult human blood pressure
and possibly, the alleviation of other cardiovascular ailments (in humans suffering essential hypertension
, taurine supplementation
resulted in measurable decreases in blood pressure).
Taurine is regularly used as an ingredient in energy drinks, with many containing 1000 mg per serving, and some as much as 2000 mg. A 2003 study by the European Food Safety Authority found no adverse effects for up to 1,000 mg of taurine per kilogram of body weight per day.
A review published in 2008 found no documented reports of negative or positive health effects associated with the amount of taurine used in energy drinks, concluding that "The amounts of guarana
, taurine, and ginseng
found in popular energy drinks are far below the amounts expected to deliver either therapeutic benefits or adverse events".
(2-hydroxyethanesulfonic acid), which in turn is obtained from the reaction of ethylene oxide
with aqueous sodium bisulfite
. Another approach is the reaction of aziridine
with sulfurous acid
. This leads directly to taurine.
In 1993, approximately 5,0006,000 tons of taurine were produced for commercial purposes; 50% for pet food manufacture, 50% in pharmaceutical applications. As of 2010, China alone has more than 40 manufacturers of taurine. Most of these enterprises employ the ethanolamine
method to produce a total annual production of about 3,000 tons.
Taurine is conjugated via its amino terminal group with chenodeoxycholic acid
and cholic acid
to form the bile salts sodium taurochenodeoxycholate and sodium taurocholate. The low pKa
of taurine's sulfonic acid group ensures this moiety
is negatively charged in the pH ranges normally found in the intestinal tract and, thus, improves the surfactant
properties of the cholic acid conjugate. Taurine crosses the blood-brain barrier
and has been implicated in a wide array of physiological phenomena including inhibitory neurotransmission
, long-term potentiation
in the striatum
/hippocampus
, membrane stabilization
, feedback inhibition of neutrophil/macrophage
respiratory burst
, adipose tissue regulation and possible prevention of obesity, calcium homeostasis
, recovery from osmotic shock
, protection against glutamate excitotoxicity
and prevention of epileptic seizures. It also acts as an antioxidant
and protects against toxicity of various substances (such as lead
and cadmium
). Additionally, supplementation with taurine has been shown to prevent oxidative stress induced by exercise. In a 2008 study, taurine has been shown to reduce the secretion of apolipoprotein B100 and lipids in HepG2 cells. High concentrations of serum lipids and apolipoprotein B100 (essential structural component of VLDL and LDL) are major risk factors of atherosclerosis
and coronary heart disease
. Hence, taurine supplementation is possibly beneficial for the prevention of these diseases. In a 2003 study, Zhang et al. have demonstrated the hypocholesterolemic (blood cholesterol-lowering) effect of dietary taurine in young overweight adults. Furthermore, they reported body weight also decreased significantly in the taurine supplemented group. These findings are consistent with animal studies. Taurine has also been shown to help people with congestive heart failure
by increasing the force and effectiveness of heart-muscle contractions.
Taurine levels were found to be significantly lower in vegans than in a control group on a standard American diet. Plasma taurine was 78% of control values, and urinary taurine was 29%.
In the cell, taurine keeps potassium and magnesium inside the cell, while keeping excessive sodium out. In this sense, it works like a diuretic. Because it aids the movement of potassium, sodium, and calcium in and out of the cell, taurine has been used as a dietary supplement
for epileptics, as well as for people who have uncontrollable facial twitches.
According to animal studies, taurine produces anxiolytic
effect and may act as a modulator or antianxiety agent in the central nervous system by activating the glycine receptor
.
Taurine is necessary for normal skeletal muscle functioning. This was shown by a 2004 study using mice with a genetic taurine deficiency. They had a nearly complete depletion of skeletal and cardiac muscle taurine levels. These mice had a reduction of more than 80% of exercise capacity compared to control mice. The authors expressed themselves as "surprised" their cardiac function showed as largely normal (given various other studies about effects of taurine on the heart).
Studies have shown taurine can influence (and possibly reverse) defects in nerve blood flow, motor nerve conduction velocity, and nerve sensory thresholds in experimental diabetic neuropathic rats. In another study on diabetic rats, taurine significantly decreased weight and decreased blood sugar
in these animal models. Likewise, a 2008 study demonstrated taurine administration to diabetic rabbits resulted in 30% decrease in serum glucose levels. According to the single study on human subjects, daily administration of 1.5g taurine had no significant effect on insulin secretion or insulin sensitivity. There is evidence that taurine may exert a beneficial effect in preventing diabetes-associated microangiopathy and tubulointerstitial injury in diabetic nephropathy
. Taurine acts as a glycation inhibitor. Studies have shown taurine-treated diabetic rats had a decrease in the formation of advanced glycation end products (AGEs) and AGEs content. The United States Department of Agriculture
has found a link between cataract development and lower levels of vitamin B6, folate, and taurine in the diets of the elderly.
Taurine has been investigated in animal studies as an alternative to glucose
as osmotic agent for use in peritoneal dialysis
solutions.
. It may also be necessary to take into consideration that absorption of taurine from beverages may be more rapid than from foods.
A 2003 study by the European Food Safety Authority found no adverse effects for up to 1,000 mg of taurine per kilogram of body weight per day.
to slowly degenerate, causing eye problems and (eventually) irreversible blindness — a condition known as central retinal degeneration (CRD), as well as hair loss and tooth decay. Decreased plasma taurine concentration has been demonstrated to be associated with feline dilated cardiomyopathy. Unlike CRD, the condition is reversible with supplementation. Taurine is now a requirement of the Association of American Feed Control Officials
(AAFCO) and any dry or wet food product labeled approved by the AAFCO should have a minimum of 0.1% taurine in dry food and 0.2% in wet food.
Research suggests taurine is essential to the normal development of passerine
birds. Many passerines seek out taurine-rich spiders to feed their young, particularly just after hatching. Researchers compared the behaviors and development of birds fed a taurine-supplemented diet to a control diet and found the juveniles fed taurine-rich diets as neonates were much larger risk takers and more adept at spatial learning tasks.
properties. It has been shown to prevent the damaging effects of TGFB1 to hair follicles. It also helps to maintain skin hydration.
Prematurely born infants are believed to lack the enzymes needed to convert cystathionine
to cysteine
, and may, therefore, become deficient in taurine. Taurine is present in breast milk
, and has been added to many infant formulas, as a measure of prudence, since the early 1980s. However, this practice has never been rigorously studied, and as such it has yet to be proven to be necessary, or even beneficial.
Taurine is also used in some contact lens solutions.
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
widely distributed in animal tissues. It is a major constituent of bile
Bile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
and can be found in the large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
and accounts for approximately 0.1% of total human body weight. Taurine has many fundamental biological roles such as conjugation of bile acid
Bile acid
Bile acids are steroid acids found predominantly in the bile of mammals. Bile salts are bile acids compounded with a cation, usually sodium. In humans, the salts of taurocholic acid and glycocholic acid represent approximately eighty percent of all bile salts. The two major bile acids are cholic...
s, antioxidation
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
, osmoregulation
Osmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too diluted or too concentrated. Osmotic pressure is a measure of the tendency of water to move...
, membrane stabilization
Membrane stabilizing effect
Membrane stabilizing effects involve the inhibition or total abolishing of action potential from being propagated across the membrane. This phenomenon is common in nerve tissues as they are the carrier of impulses from the periphery to the central nervous system. Membrane stabilization is the...
and modulation of calcium signaling
Calcium signaling
Calcium is a common signaling mechanism, as once it enters the cytoplasm it exerts allosteric regulatory effects on many enzymes and proteins...
. It is essential for cardiovascular
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
function, and development and function of skeletal muscle
Skeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
, the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
and the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
. Taurine is unusual among biological molecules in being a sulfonic acid
Sulfonic acid
Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...
, while the vast majority of biologically occurring acids contain the more weakly acidic carboxyl group. While taurine is sometimes called an amino acid, and indeed is an acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
containing an amino group, it is not an amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
in the usual biochemical meaning of the term, which refers to compounds containing both an amino and a carboxyl group.
Discovery and etymology
Taurine is named after the Latin taurus (a cognateCognate
In linguistics, cognates are words that have a common etymological origin. This learned term derives from the Latin cognatus . Cognates within the same language are called doublets. Strictly speaking, loanwords from another language are usually not meant by the term, e.g...
of the Greek ταύρος) which means bull or ox, as it was first isolated from ox
Ox
An ox , also known as a bullock in Australia, New Zealand and India, is a bovine trained as a draft animal. Oxen are commonly castrated adult male cattle; castration makes the animals more tractable...
bile in 1827 by German scientists Friedrich Tiedemann
Friedrich Tiedemann
Friedrich Tiedemann was a German anatomist and physiologist.He was born at Cassel, the eldest son of Dietrich Tiedemann , a philosopher and psychologist of considerable repute. He graduated in medicine at Marburg in 1804, but soon abandoned practice...
and Leopold Gmelin
Leopold Gmelin
Leopold Gmelin was a German chemist.Gmelin was the son of Johann Friedrich Gmelin. He studied medicine and chemistry at Göttingen, Tübingen and Vienna, and in 1813 began to lecture on chemistry at Heidelberg, where in 1814 he was appointed extraordinary-, and in 1817 ordinary-, professor of...
.
Structure
Taurine is a derivative of cysteineCysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
, an amino acid which contains a sulfhydryl
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
group. Taurine is one of the few known naturally occurring sulfonic acid
Sulfonic acid
Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...
s. In the strict sense, it is not an amino acid, as it lacks a carboxyl group
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
, but it is often called one, even in scientific literature. It does contain a sulfonate group
Sulfonate
A sulfonate is a salt or ester of a sulfonic acid. It contains the functional group R-SO2O-.- Sulfonate salts:Anions with the general formula RSO2O− are called sulfonates. They are the conjugate bases of sulfonic acids with formula RSO2OH. As sulfonic acids tend to be strong acids, the...
and may be called an amino sulfonic acid. Small polypeptides have been identified which contain taurine, but to date no aminoacyl tRNA synthetase
Aminoacyl tRNA synthetase
An aminoacyl tRNA synthetase is an enzyme that catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. This is sometimes called "charging" the tRNA with the amino acid...
has been identified as specifically recognizing taurine and capable of incorporating it into a tRNA
Transfer RNA
Transfer RNA is an adaptor molecule composed of RNA, typically 73 to 93 nucleotides in length, that is used in biology to bridge the three-letter genetic code in messenger RNA with the twenty-letter code of amino acids in proteins. The role of tRNA as an adaptor is best understood by...
.
Dietary intake
Taurine occurs naturally in food, especially in seafood and meat. The mean daily intake from omnivore diets was determined to be around 58 mg (range from 9 to 372 mg) and to be low or negligible from a strict vegan diet. In another study, taurine intake was estimated to be generally less than 200 mg/day, even in individuals eating a high-meat diet. According to another study, taurine consumption was estimated to vary between 40 and 400 mg/day.Biosynthesis
Taurine is a major constituent of bile and can be found in the large intestine and in the tissues of many animals, including humans. Mammalian taurine synthesis occurs in the pancreas via the cysteine sulfinic acid pathway. In this pathway, the sulfhydryl group of cysteineCysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
is first oxidized to cysteine sulfinic acid by the enzyme cysteine dioxygenase
Cysteine dioxygenase
Cysteine dioxygenase ) is a mammalian non-heme iron enzyme that catalyzes the conversion of L-cysteine to cysteine sulfinic acid by incorporation of dioxygen....
. Cysteine sulfinic acid, in turn, is decarboxylated by sulfinoalanine decarboxylase
Sulfinoalanine decarboxylase
In enzymology, a sulfinoalanine decarboxylase is an enzyme that catalyzes the chemical reactionHence, this enzyme has one substrate, 3-sulfino-L-alanine, and two products, hypotaurine and CO2....
to form hypotaurine
Hypotaurine
Hypotaurine is a sulfinic acid that is an intermediate in the biosynthesis of taurine. Like taurine, it also acts as an endogenous neurotransmitter via action on the glycine receptors.- References :...
. It is unclear whether hypotaurine is then spontaneously or enzymatically oxidized to yield taurine.
Nutritional significance
Despite being present in many energy drinks and dietary supplements, and being a required nutrient for some animals, taurine has not been shown to be beneficial in human nutrition. A study of mice hereditarily unable to transport taurine suggests that it is needed for proper maintenance and functioning of skeletal muscleSkeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
s. In addition, it has been shown to be effective in removing fatty liver deposits in rats, preventing liver disease, and reducing cirrhosis
Cirrhosis
Cirrhosis is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrosis, scar tissue and regenerative nodules , leading to loss of liver function...
in tested animals. There is also evidence that taurine is beneficial for adult human blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
and possibly, the alleviation of other cardiovascular ailments (in humans suffering essential hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
, taurine supplementation
Dietary supplement
A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
resulted in measurable decreases in blood pressure).
Taurine is regularly used as an ingredient in energy drinks, with many containing 1000 mg per serving, and some as much as 2000 mg. A 2003 study by the European Food Safety Authority found no adverse effects for up to 1,000 mg of taurine per kilogram of body weight per day.
A review published in 2008 found no documented reports of negative or positive health effects associated with the amount of taurine used in energy drinks, concluding that "The amounts of guarana
Guarana
Guarana , Paullinia cupana, syn. P. crysan, P. sorbilis) is a climbing plant in the maple family, Sapindaceae, native to the Amazon basin and especially common in Brazil. Guarana features large leaves and clusters of flowers, and is best known for its fruit, which is about the size of a coffee bean...
, taurine, and ginseng
Ginseng
Ginseng is any one of eleven species of slow-growing perennial plants with fleshy roots, belonging to the genus Panax of the family Araliaceae....
found in popular energy drinks are far below the amounts expected to deliver either therapeutic benefits or adverse events".
Chemical synthesis and commercial production
Synthetic taurine is obtained from isethionic acidIsethionic acid
Isethionic acid is a short chain alkane sulfonic acid containing hydroxy group, is a water soluble solid used in the manufacture of mild, biodegradable and high foaming anionic surfactants for skin cleansing....
(2-hydroxyethanesulfonic acid), which in turn is obtained from the reaction of ethylene oxide
Ethylene oxide
Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...
with aqueous sodium bisulfite
Sodium bisulfite
Sodium bisulfite is a chemical compound with the chemical formula NaHSO3. Sodium bisulfite is a food additive with E number E222. This salt of bisulfite can be prepared by bubbling sulfur dioxide in a solution of sodium carbonate in water...
. Another approach is the reaction of aziridine
Aziridine
Aziridines are organic compounds containing the aziridine functional group, a three-membered heterocycle with one amine group and two methylene groups...
with sulfurous acid
Sulfurous acid
Sulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...
. This leads directly to taurine.
In 1993, approximately 5,0006,000 tons of taurine were produced for commercial purposes; 50% for pet food manufacture, 50% in pharmaceutical applications. As of 2010, China alone has more than 40 manufacturers of taurine. Most of these enterprises employ the ethanolamine
Ethanolamine
Ethanolamine, also called 2-aminoethanol or monoethanolamine , is an organic chemical compound that is both a primary amine and a primary alcohol . Like other amines, monoethanolamine acts as a weak base...
method to produce a total annual production of about 3,000 tons.
Physiological functions
Taurine is essential for cardiovascular function, and development and function of skeletal muscle, the retina and the central nervous system.Taurine is conjugated via its amino terminal group with chenodeoxycholic acid
Chenodeoxycholic acid
Chenodeoxycholic acid is a bile acid. It occurs as a white crystalline substance insoluble in water but soluble in alcohol and acetic acid, with melting point at 165-167 °C. Salts of this carboxylic acid are called chenodeoxycholates...
and cholic acid
Cholic acid
Cholic acid is a bile acid, a white crystalline substance insoluble in water , with a melting point of 200-201 °C. Salts of cholic acid are called cholates. Cholic acid, along with chenodeoxycholic acid, is one of two major bile acids produced by the liver where it is synthesized from cholesterol...
to form the bile salts sodium taurochenodeoxycholate and sodium taurocholate. The low pKa
PKA
PKA, pKa, or other similar variations may stand for:* pKa, the symbol for the acid dissociation constant at logarithmic scale* Protein kinase A, a class of cAMP-dependent enzymes* Pi Kappa Alpha, the North-American social fraternity...
of taurine's sulfonic acid group ensures this moiety
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
is negatively charged in the pH ranges normally found in the intestinal tract and, thus, improves the surfactant
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
properties of the cholic acid conjugate. Taurine crosses the blood-brain barrier
Blood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
and has been implicated in a wide array of physiological phenomena including inhibitory neurotransmission
Neurotransmission
Neurotransmission , also called synaptic transmission, is the process by which signaling molecules called neurotransmitters are released by a neuron , and bind to and activate the receptors of another neuron...
, long-term potentiation
Long-term potentiation
In neuroscience, long-term potentiation is a long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously. It is one of several phenomena underlying synaptic plasticity, the ability of chemical synapses to change their strength...
in the striatum
Striatum
The striatum, also known as the neostriatum or striate nucleus, is a subcortical part of the forebrain. It is the major input station of the basal ganglia system. The striatum, in turn, gets input from the cerebral cortex...
/hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...
, membrane stabilization
Membrane stabilizing effect
Membrane stabilizing effects involve the inhibition or total abolishing of action potential from being propagated across the membrane. This phenomenon is common in nerve tissues as they are the carrier of impulses from the periphery to the central nervous system. Membrane stabilization is the...
, feedback inhibition of neutrophil/macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
respiratory burst
Respiratory burst
Respiratory burst is the rapid release of reactive oxygen species from different types of cells....
, adipose tissue regulation and possible prevention of obesity, calcium homeostasis
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
, recovery from osmotic shock
Osmotic shock
Osmotic shock or osmotic stress is a sudden change in the solute concentration around a cell, causing a rapid change in the movement of water across its cell membrane. Under conditions of high concentrations of either salts, substrates or any solute in the supernatant, water is drawn out of the...
, protection against glutamate excitotoxicity
Excitotoxicity
Excitotoxicity is the pathological process by which nerve cells are damaged and killed by excessive stimulation by neurotransmitters such as glutamate and similar substances. This occurs when receptors for the excitatory neurotransmitter glutamate such as the NMDA receptor and AMPA receptor are...
and prevention of epileptic seizures. It also acts as an antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
and protects against toxicity of various substances (such as lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
and cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
). Additionally, supplementation with taurine has been shown to prevent oxidative stress induced by exercise. In a 2008 study, taurine has been shown to reduce the secretion of apolipoprotein B100 and lipids in HepG2 cells. High concentrations of serum lipids and apolipoprotein B100 (essential structural component of VLDL and LDL) are major risk factors of atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
and coronary heart disease
Coronary heart disease
Coronary artery disease is the end result of the accumulation of atheromatous plaques within the walls of the coronary arteries that supply the myocardium with oxygen and nutrients. It is sometimes also called coronary heart disease...
. Hence, taurine supplementation is possibly beneficial for the prevention of these diseases. In a 2003 study, Zhang et al. have demonstrated the hypocholesterolemic (blood cholesterol-lowering) effect of dietary taurine in young overweight adults. Furthermore, they reported body weight also decreased significantly in the taurine supplemented group. These findings are consistent with animal studies. Taurine has also been shown to help people with congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
by increasing the force and effectiveness of heart-muscle contractions.
Taurine levels were found to be significantly lower in vegans than in a control group on a standard American diet. Plasma taurine was 78% of control values, and urinary taurine was 29%.
In the cell, taurine keeps potassium and magnesium inside the cell, while keeping excessive sodium out. In this sense, it works like a diuretic. Because it aids the movement of potassium, sodium, and calcium in and out of the cell, taurine has been used as a dietary supplement
Dietary supplement
A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
for epileptics, as well as for people who have uncontrollable facial twitches.
According to animal studies, taurine produces anxiolytic
Anxiolytic
An anxiolytic is a drug used for the treatment of anxiety, and its related psychological and physical symptoms...
effect and may act as a modulator or antianxiety agent in the central nervous system by activating the glycine receptor
Glycine receptor
The glycine receptor, or GlyR, is the receptor for the amino acid neurotransmitter glycine. GlyR is an ionotropic receptor that produces its effects through chloride current...
.
Taurine is necessary for normal skeletal muscle functioning. This was shown by a 2004 study using mice with a genetic taurine deficiency. They had a nearly complete depletion of skeletal and cardiac muscle taurine levels. These mice had a reduction of more than 80% of exercise capacity compared to control mice. The authors expressed themselves as "surprised" their cardiac function showed as largely normal (given various other studies about effects of taurine on the heart).
Studies have shown taurine can influence (and possibly reverse) defects in nerve blood flow, motor nerve conduction velocity, and nerve sensory thresholds in experimental diabetic neuropathic rats. In another study on diabetic rats, taurine significantly decreased weight and decreased blood sugar
Blood sugar
The blood sugar concentration or blood glucose level is the amount of glucose present in the blood of a human or animal. Normally in mammals, the body maintains the blood glucose level at a reference range between about 3.6 and 5.8 mM , or 64.8 and 104.4 mg/dL...
in these animal models. Likewise, a 2008 study demonstrated taurine administration to diabetic rabbits resulted in 30% decrease in serum glucose levels. According to the single study on human subjects, daily administration of 1.5g taurine had no significant effect on insulin secretion or insulin sensitivity. There is evidence that taurine may exert a beneficial effect in preventing diabetes-associated microangiopathy and tubulointerstitial injury in diabetic nephropathy
Diabetic nephropathy
Diabetic nephropathy , also known as Kimmelstiel-Wilson syndrome, or nodular diabetic glomerulosclerosis and intercapillary glomerulonephritis, is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. It is characterized by nephrotic syndrome and diffuse...
. Taurine acts as a glycation inhibitor. Studies have shown taurine-treated diabetic rats had a decrease in the formation of advanced glycation end products (AGEs) and AGEs content. The United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
has found a link between cataract development and lower levels of vitamin B6, folate, and taurine in the diets of the elderly.
Taurine has been investigated in animal studies as an alternative to glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
as osmotic agent for use in peritoneal dialysis
Peritoneal dialysis
Peritoneal dialysis is a treatment for patients with severe chronic kidney disease. The process uses the patient's peritoneum in the abdomen as a membrane across which fluids and dissolved substances are exchanged from the blood...
solutions.
Toxicity
Taurine is involved in a number of crucial physiological processes. However, the role of taurine in these processes is not clearly understood and the influence of high taurine doses on these processes is uncertain. A substantial increase in the plasma concentration of growth hormone was reported in some epileptic patients during taurine tolerance testing (oral dose of 50 mg/kg bw/day), suggesting a potential to stimulate the hypothalamus and to modify neuroendocrine function. There is an indication that taurine (2 g/day) has some function in the maintenance and possibly in the induction of psoriasisPsoriasis
Psoriasis is an autoimmune disease that appears on the skin. It occurs when the immune system mistakes the skin cells as a pathogen, and sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious. However, psoriasis has been linked to an increased risk of...
. It may also be necessary to take into consideration that absorption of taurine from beverages may be more rapid than from foods.
A 2003 study by the European Food Safety Authority found no adverse effects for up to 1,000 mg of taurine per kilogram of body weight per day.
In animal nutrition
Taurine is an essential dietary requirement for feline health, since cats cannot synthesize the compound. The absence of taurine causes a cat's retinaRetina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
to slowly degenerate, causing eye problems and (eventually) irreversible blindness — a condition known as central retinal degeneration (CRD), as well as hair loss and tooth decay. Decreased plasma taurine concentration has been demonstrated to be associated with feline dilated cardiomyopathy. Unlike CRD, the condition is reversible with supplementation. Taurine is now a requirement of the Association of American Feed Control Officials
Association of American Feed Control Officials
The Association of American Feed Control Officials is a non-profit organization which sets standards for the quality and safety of animal feed and pet food in the United States. AAFCO is a voluntary organization consisting largely of state officials who have responsibility for enforcing their...
(AAFCO) and any dry or wet food product labeled approved by the AAFCO should have a minimum of 0.1% taurine in dry food and 0.2% in wet food.
Research suggests taurine is essential to the normal development of passerine
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
birds. Many passerines seek out taurine-rich spiders to feed their young, particularly just after hatching. Researchers compared the behaviors and development of birds fed a taurine-supplemented diet to a control diet and found the juveniles fed taurine-rich diets as neonates were much larger risk takers and more adept at spatial learning tasks.
Other uses
Lately, cosmetic compositions containing taurine have been introduced, possibly due to its antifibroticFibrosis
Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process. This is as opposed to formation of fibrous tissue as a normal constituent of an organ or tissue...
properties. It has been shown to prevent the damaging effects of TGFB1 to hair follicles. It also helps to maintain skin hydration.
Prematurely born infants are believed to lack the enzymes needed to convert cystathionine
Cystathionine
Cystathionine is an intermediate in the synthesis of cysteine.It is generated from homocysteine and serine by cystathionine beta synthase.It is cleaved into cysteine and α-ketobutyrate by cystathionine gamma-lyase....
to cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
, and may, therefore, become deficient in taurine. Taurine is present in breast milk
Breast milk
Breast milk, more specifically human milk, is the milk produced by the breasts of a human female for her infant offspring...
, and has been added to many infant formulas, as a measure of prudence, since the early 1980s. However, this practice has never been rigorously studied, and as such it has yet to be proven to be necessary, or even beneficial.
Taurine is also used in some contact lens solutions.