Taurine is a naturally occurring sulfonic acid, which is often cited as a non essential amino acid. Its full structural name is 2-aminoethanesulfonic acid, and is abundantly found in a large amount of animal tissues[1]. As a conditional organic acid, it is synthesised by the body and does not always need to be taken in through the diet, however additional supplementation of taurine can give rise to a range of benefits. Technically speaking, Taurine is not an amino acid in the scientific sense, despite being labelled as one in a large number of publications. Amino acids contain both a Carboxylic Acid (COOH) group as well as an Amine (NH2) group. Taurine however does not contain a Carboxylic Acid group, instead consisting of one Amine group and one Sulfonate group.

How is Taurine synthesised?

Taurine is biosynthesised in the human pancreas, a small organ located behind the stomach which produces hormones and enzymes from its glands[2]. The chemical precursor to Taurine is the sulphur-contining amino acid Cysteine. This is first oxidised to Cysteine sulfinic acid, by the action of the enzyme Cysteine dioxegenase, where two oxygen groups are added to the Cysteine molecule. Cysteine sulfinic acid is then decarboxylated (removal of a carbon dioxide group) by the enzyme Sulfinoalanine decarboxylase. This produces an intermediate compound known as hypotaurine. In the third and final step of Taurine synthesis, Hypotaurine is oxidised further to give Taurine. It is also synthesised in the testes of adult males.

Benefits of Taurine to the body

This organic acid has a number of beneficial uses to the human body. One important property of Taurine is its ability to cross the blood brain barrier[3]. The blood vessels which supply the cerebral cortex are surrounded by a number of specific enhancements, such as endothelial cells joined by “tight junctions”, perictye cells and astrocyte cells. These serve as functional barriers which highly regulate the substances that can pass from the blood into the neuronal structure of the brain, as many chemicals can severely harm the brain tissue. Taurine is capable of passing through this barrier, and so is involved in a range of physiological processes such as neurotransmission between nerve synapses, calcium homeostasis and membrane stabilisation[4]. Through its effects on the brain it can reportedly also increase cognitive performance and mental ability. Taurine is also found in bile, a fluid produced by the liver which aids in the digestion of fats and lipids in the stomach. The release of the glucose-lowering hormone insulin has also been shown to be affected by Taurine levels. Studies demonstrate that, combined with the glucose stimulus, Taurine can increase the amount of insulin released from pancreatic beta cells into the bloodstream[5]. As Taurine is involved in calcium homeostasis, when it enters the beta cells it is likely to initiate an influx of calcium ions through voltage gated channels. These calcium ions cause the insulin containing vesicles to fuse with the beta cell membrane and release their contents out into the blood. Another benefit of taurine is its involvement in protecting the “rod” cells which form part of the retina[6]. It does this by providing a defence against oxidative attack, as well as removing toxic substances. Taurine also functions as a diuretic, as it helps keep potassium and magnesium ions inside cells, whilst keeping sodium out of them. This encourages the excretion of sodium from the system in the urine, a process which takes place in the kidneys. Furthermore, there is an important function for Taurine in skeletal muscle movement and functioning. Removal of the Taurine transporter (which results in very low levels of Taurine inside the skeletal muscle cells) caused a huge decrease of up to 80% in exercise capacity, with large electromyographic abnormalities found upon later analysis[7].

Medical Applications for Taurine

As shown, Taurine is involved in a wide range of physiological processes and serves numerous functions within the body. There have been several identified medical uses of Taurine. Due to its ability to stimulate insulin production, taurine has sometimes been used as a supplement for diabetic patients with abnormally high blood sugar levels. As well as possibly lowering glucose levels, it can also help prevent diabetes-related complications such as microangiopathy and nephropathy, which are diseases affecting small blood vessels and the kidney, respectively. Congestive Heart Failure {CHF} is a disease whereby the heart is unable to effectively pump blood to all the organ systems, due to low cardiac output. Taurine supplementation has demonstrated impressive improvements in patients with congestive heart failure, and out of 24 patients in the particular study, 19 were found to have reduced severity after 8 weeks. 13 patients who had previously been diagnosed as having functional class III or IV CHF (more severe), could be re-designated as class II (less severe) after the study[9]. It does this by increasing the force of cardiac muscle contraction through promoting proper calcium ion balance, which is required for effective shortening of muscle fibres. Other cardiovascular conditions such as atherosclerosis can also be prevented through Taurine supplementation. Homocysteine is a sulphur containing amino acid which is frequently linked to risk of coronary artery disease. Taurine acts as a direct antagonist to homocysteine, reducing its concentration in the blood plasma significantly[10]. Studies on both humans and animals have also shown Taurine’s hypocholesterolemic effects in overweight adults (lowering of cholesterol), and thus a reduction in body weight[11], and so could be used to treat or prevent obesity and the complications which arise from it.

Foods high in Taurine

Several foods have naturally high Taurine levels, and a balanced diet involving these foods can help provide the various benefits of this substance. Fish such as salmon and mackerel have relatively high (4-9g) levels of taurine per kilogram of dry weight. Meat products such as beef, chicken and lamb all have substantial Taurine content, as well as dairy products such as milk. Due to its importance for newborn babies, Taurine is also highly abundant in breast milk.

Conclusion

Taurine is an important organic acid which has been shown in numerous studies to have positive effects on the health of various organ systems and bodily processes. Despite our bodies naturally synthesising it, Taurine deficiencies are often identified and increasing the level of this substance in the body is necessary. Both food products and supplements can be incorporated into one’s daily diet in order to maintain general health, as well as combat specific medical conditions and diseases, in certain cases.

[1] Bouckenooghe T, Remacle C, Reusens B (2006). “Is taurine a functional nutrient?”. Current Opinion in Clinical Nutrition and Metabolic Care, Vol 9 (6): 728–33.

[2] “Taurine and Hypotaurine Metabolism” http://pathman.smpdb.ca/pathways/SMP00021/pathway

[3] Hayat Benrabh, Jean-Marie Bourre, Jeanne-Marie Lefauconnier “Taurine transport at the blood-brain barrier: an in vivo brain perfusion study”, Brain Research, Volume 692, Issues 1–2, Pages 1-289 (18 September 1995)

[4]Birdsall, TC (1998). “Therapeutic applications of taurine”. Alternative Medicine Review 3 (2): 128–36

[5] William J L’Amoreaux1, Christina Cuttitta1, Allison Santora1, Jonathan F Blaize1, Janto Tachjadi1, and Abdeslem El Idrissi1, “Taurine regulates insulin release from pancreatic beta cell lines”, Journal of Biomedical Science, Vol 17

[6] López-Escalera R, Morán J, Pasantes-Morales H. “Taurine and nifedipine protect retinal rod outer segment structure altered by removal of divalent cations.” Journal of Neuroscience Research, Volume 19 (4):491-6.

[7] Warskulat U, Flögel U, Jacoby C, Hartwig HG, Thewissen M, Merx MW, Molojavyi A, Heller-Stilb B, Schrader J, Häussinger D. “Taurine transporter knockout depletes muscle taurine levels and results in severe skeletal muscle impairment but leaves cardiac function uncompromised.” Federation of American Societies for Experimental Biology, 2004 Mar;18(3):577-9

[8] Verzola, D; Bertolotto, MB; Villaggio, B; Ottonello, L; Dallegri, F; Frumento, G; Berruti, V; Gandolfo, MT et al. (2002). “Taurine prevents apoptosis induced by high ambient glucose in human tubule renal cells”. Journal of investigative medicine: the official publication of the American Federation for Clinical Research

[9] Azuma J, Hasegawa H, Sawamura A, Awata N, Ogura K, Harada H, Yamamura Y, Kishimoto S. “Therapy of congestive heart failure with orally administered taurine.” Clinical Therapeutics, Vol 5

[10] “Effect of taurine supplementation on plasma homocysteine levels of the middle-aged Korean women”, Advances in Experimental Medicine and Biology, 2009;643:415-22

[11]Zhang, M; Bi, LF; Fang, JH; Su, XL; Da, GL; Kuwamori, T; Kagamimori, S (2004). “Beneficial effects of taurine on serum lipids in overweight or obese non-diabetic subjects”. Amino Acids 26 (3): 267–71