Taurine was first identified and isolated from the bile of the ox (Bos taurus), from which it derives its name. It is an important amino acid with many functions in the body including osmoregulation and calcium homeostasis. It provides substrate for bile salt synthesis and supports a number of bodily systems, particularly the nervous system1.
It is one of a few amino acids which are not used in protein synthesis and has therefore been considered non-essential or more generously as a “conditionally essential” amino acid. It also differs from other amino acids as instead of possessing a carboxyl group (typical of amino acids) it possesses a sulfonate group1.
Even though it may not behave as a regular amino acid it has multiple benefits to health and therefore should be an essential consideration for dietary and potentially supplemental intake. This blog discusses the functions and therapeutic benefit of this unique molecule.
Functions of Taurine:
Taurine is an organic osmolyte involved in cell volume regulation. It provides substrate for the formation of bile salts, plays a role in the modulation of intracellular free calcium concentration, and is one of the most abundant amino acids in the brain, retina, muscle tissue and organs throughout the body. Taurine serves a wide variety of functions in the central nervous system, from development to cell protection, and taurine deficiency is associated with cardiomyopathy, renal dysfunction, developmental abnormalities, and severe damage to retinal neurons2.
Bile acid conjugation
Taurine is conjugated with bile acids in order to form a number of bile salts. Bile salts are essential for both the emulsification, and therefore absorption of fats, as well as the removal of waste products from the liver, including cholesterol. As taurine is involved in the production of bile salts there is support for its use being helpful for fatty acid status and liver function. Studies suggest that taurine supplementation increases the synthesis and excretion of taurine-conjugated bile salts and stimulates the catabolism of cholesterol to bile acids by elevating the expression and activity of CYP7A1. This may reduce cholesterol esterification and lipoprotein assembly for very low density lipoprotein (VLDL) secretion, leading to reductions in the serum and hepatic cholesterol levels3,2.
Maintenance of calcium homeostasis
Intracellular calcium dysregulation is significantly correlated with the progression of chronic conditions including cardiovascular disease and dementia. Taurine has been shown to aid the maintenance of calcium homeostasis. Taurine transporters can remove taurine from cells which is accompanied by the loss of sodium ions (Na+) from cells. Therefore less Na+ is available for calcium ion (Ca+) entry via the Na+/Ca+ exchanger which reduces the amount of calcium overload. Also, taurine indirectly regulates the activity of the enzyme sarcoplasmic reticular Ca2+ ATPase, which is responsible for maintaining cytosolic Ca2+ homeostasis through the removal of Ca2+ from the cytosol. Hence taurine plays a key role in protecting the normal function and integrity of the cell2.
Taurine serves as an organic osmolyte (i.e. water will travel across cell membranes towards taurine). Intracellular concentrations of taurine will fluctuate in response to osmotic tone, increasing when hypotonic and decreasing when hypertonic within the cell. This mechanism helps to protect the cell from excessive stretching in response to osmotic imbalances. It also modulates the levels of other osmolytes, such as Na+, which not only carries a charge (unlike taurine which is neutral) but is also involved in many important cellular functions, such as transport and membrane potential. In the kidney, taurine serves as a weak diuretic and natriuretic agent, important properties for normal renal function2,4.
Immunity and inflammation
The fundamental role of taurine in the immune system is related to its antioxidant properties. Taurine protects tissues from oxidative stress associated with the pathology of various inflammatory diseases.
Taurine is the component (or modulator) of the myeloperoxidase–halide system; this system plays a unique role in killing pathogens phagocytosed by neutrophils through generation of hypochlorous acid (HOCl), a potent microbial and cytotoxic oxidant. HOCl and the similar HOBr react with taurine to produce taurine haloamines (TauCl/TauBr), which are less toxic milder oxidants, but retain antimicrobial and anti-inflammatory properties. Therefore taurine is involved in detoxifying by-products of the inflammatory process in order to make them less toxic. Taurine and taurine haloamines are components of innate immunity.
In vitro and in vivo studies, as well as clinical trials, support taurine and taurine derivatives as being considered as therapeutic molecules for infectious and chronic inflammatory disease2,5.
Membrane stabilisation and cytoprotection
Taurine has many properties which protect cells, stabilise membranes and support mitochondrial health and therefore support the maintenance of normal cellular functions. These include:
- Neutralises hypochlorous acid, a neutrophil oxidant, to produce taurine chloramine, therefore indirectly reducing oxidative stress
- Diminishes the generation of superoxide free radicals by the mitochondria
- Prevents damage to other antioxidant enzymes by reactive oxygen species within the mitochondria2
- Increasing taurine levels restores respiratory chain activity and increases the synthesis of ATP at the expense of superoxide anion production. If the respiratory chain becomes dysfunctional there is a reduction of ATP production and an increase in the superoxide free radical
- Activates complex I and NADH sensitive enzymes by reducing NADH/NAD+ ratio during glycolysis, therefore supporting normal energy production by freeing up NAD+ to remove H+ and allow glycolysis to continue running
- Taurine deficiency is associated with low levels of PPARα and therefore a suppression of fatty acid oxidation. PPARα regulates several proteins and enzymes involved in fatty acid metabolism, with the most important being the acyl carnitine transporter complex2
In order to protect cells, it is important that mechanisms are in place such as antioxidant systems, support for autophagy (the natural, regulated mechanism of the cell that disassembles unnecessary or dysfunctional components), maintenance of cellular homeostasis and normal protein synthesis. Taurine’s cytoprotective mechanisms include:
- Suppression of glutamate-induced toxicity through several pathways and protection of neurons from oxidative stress
- Attenuation of endoplasmic reticular stress (the endoplasmic reticulum is where protein is synthesised in the cell). ER stress is an important regulatory mechanism designed to restore ER function and re-establish a balance between protein degradation and protein biosynthesis/folding
- Protection of cardiomyocytes by activating ubiquitin-proteasome system and autophagy
- Attenuation of toxin-mediated autophagy
- Modulation of genes to induce longevity
Insulin Resistance – Taurine has shown potential, in animal studies, in modulating insulin resistance and other risk factors in both type 1 and 2 diabetes. It has been shown to improve insulin sensitivity by modifying the post-receptor events of insulin action. In addition it has been shown to prevent high glucose-induced microangiopathy, i.e vascular endothelial cell apoptosis, and in fructose-fed rats, it has been found to restore glucose metabolising enzyme activities.
A study in 1995 also found that taurine ameliorates diabetic nephropathy by decreasing lipid peroxidation and lessening the accumulation of advanced glycation end-products in the kidney2.
Eyes – Taurine is the most abundant amino acid in the retina, vitreous, lens, cornea, iris and ciliary body. It is demonstrated that taurine serves a neuroprotective role in ganglion cells, as well as in photoreceptors. It has been proposed that taurine therapy may serve an important role in the prevention of retinal degeneration1.
Stroke – Under pathological conditions, such as ischemic stroke and hypo-osmotic stress, taurine is released from various cells in the central nervous system (CNS) and functions as a neuroprotective agent. Glutamate release can occur post-stroke leading to glutamate toxicity. Taurine has been shown to attenuate many symptoms of this including: calcium overload, oxidative stress, ATP depletion and mitochondrial dysfunction2.
Neurodegenerative diseases – Drivers of neurodegenerative diseases include glutamate toxicity, calcium overload and an increase in ROS production. Because mitochondrial function is adversely affected by neurodegeneration, mitochondrial ROS generation is considered to be a major cause of cellular damage. Dysfunction of the electron transport chain has been identified in conditions such as Huntington’s and Alzheimer’s disease. It has been reported that reduced plasma taurine content is associated with motor severity in Parkinson’s disease2,6.
Cardiovascular support – There have been a number of studies which have shown taurine to be protective of the cardiovascular system, likely due to a combination of its antioxidant, anti-inflammatory, mitochondrial supportive and cytoprotective properties. Taurine has been found to be deficient in patients suffering from heart failure. In Japan taurine has been approved for the treatment of congestive heart failure. It is also used as an anti-arrhythmic agent, to lower blood pressure and reduce atherosclerosis.2
Congestive heart failure (CHF) – Taurine diminishes the common symptoms of CHF (breathlessness on exertion and oedema) but it also has been demonstrated to eliminate or decrease the need for administering other heart failure medication.
Hypertension – In animal models taurine demonstrated a reduction in blood pressure via a combination of diminished Ca2+, oxidative stress, sympathetic activity and inflammatory activity, as well as an improvement in renal function.
Atherosclerosis – It has been shown to reduce atherogenesis by several mechanisms, including by maintaining lipid homeostasis, supporting calcium regulation and reduction of oxidative stress and inflammation2.
Anti-Arrhythmic – One of the earliest reported cardiovascular actions of taurine is its antiarrhythmic actions. This effect is likely related to the modulation of sodium, potassium and calcium ions. Clinical reports have shown oral administration of taurine and L-arginine dramatically reduced cardiac arrhythmias in subjects2.
It has been suggested that taurine may be useful for attenuation of all inflammatory conditions. However there is particular interest in taurine as a therapeutic for rheumatoid arthritis2,5.
Important dietary sources of taurine are fish and seafood, meat also contains a modest amount. In addition taurine can be synthesised in the body, from other sulphur containing amino acids (methionine and cysteine). The rate of biosynthesis is low and requires pyridoxal-5-phosphate (the active coenzyme form of vitamin B6) as a cofactor. A vitamin B6 deficiency has been shown to impair taurine synthesis. Thus taurine is classed as a ‘conditionally essential’ nutrient. Conditionally essential amino acids can be made in the body, however they may become ‘essential’ in certain circumstances (e.g. when needs increase). Essential refers to the fact that they must be obtained from food.
- Taurine is an amino acid which is not incorporated into proteins.
- It was originally identified in bile salts and it is important for bile acid conjugation, therefore it supports lipid homeostasis and absorption as well as excretion of waste products via the liver.
- Taurine acts as an osmoregulator (balances water levels inside and outside cells) and as a result of this also helps to maintain calcium homeostasis. Therefore it helps to protect cells and maintain their tone and structure.
- Taurine has also been shown to act as an antioxidant and this property supports energy production by the mitochondria, protecting them from damage by reactive oxygen species.
- It has anti-inflammatory effects by neutralising pro-inflammatory by-products of metabolism.
- All of these properties have identified taurine as a potential therapy for conditions including insulin resistance and diabetes, stroke, rheumatoid arthritis, congestive heart failure, hypertension, atherosclerosis and neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
- Taurine is abundant in nervous tissue including the brain and the eyes. It is involved in neuroprotection and has been demonstrated to prevent retinal degeneration.
If you have questions regarding the topics that have been raised, or any other health matters, please do contact me (Helen) by phone or email at any time.
[email protected], 01684 310099
Helen Drake and the Cytoplan Editorial Team
L-Taurine – provides 500mg of L-Taurine per capsule
- Ripps H, Shen W. Review: taurine: a "very essential" amino acid. Mol Vis. 2012;18:2673-2686. http://www.ncbi.nlm.nih.gov/pubmed/23170060. Accessed June 26, 2019.
- Schaffer S, Kim HW. Effects and Mechanisms of Taurine as a Therapeutic Agent. Biomol Ther (Seoul). 2018;26(3):225-241.
- Murakami S, Fujita M, Nakamura M, et al. Taurine ameliorates cholesterol metabolism by stimulating bile acid production in high-cholesterol-fed rats. Clin Exp Pharmacol Physiol. 2016;43(3):372-378.
- Schaffer S, Takahashi K, Azuma J. Role of osmoregulation in the actions of taurine. Amino Acids. 2000;19(3-4):527-546. http://www.ncbi.nlm.nih.gov/pubmed/11140357.
- Marcinkiewicz J, Kontny E. Taurine and inflammatory diseases. Amino Acids. 2014;46(1):7. d
- Chen C, Xia S, He J, Lu G, Xie Z, Han H. Roles of taurine in cognitive function of physiology, pathologies and toxication. Life Sci. 2019;231:116584.