1.Introduction

Taurine is name after the Greek taurus, which means bull, as it was first isolated from bull (Bos taurus) bile in 1827 by Austrian scientists Friedrich Tiedermenn and Leopold Gmelin. It is often called an amino acid, even in scientific literature, but it lacks a carboxyl group and therefore does not qualify as an amino acid in Biological terminology. It does contain a sulfonate group and may be called an amino sulfonic acid. It is not incorporated into proteins.

Taurine present in virtually all cells throughout the animal kingdom, particularly in electrically excitable tissue such as brain, retina, heart and skeletal muscle.  is  essentially  absent  in  plants,  with small  amounts  found  in  lower plant  forms (Hyes. 1981).

Taurine appear to involve in the functional regulation of many mammalian organ system.

2.Taurine chemistry

Taurine (2-aminoethanesulfonic acid) has the amino group on the betacarbon, and has a sulfonic acid group in place of carboxylic acid group. It is a colorless, relatively tasteless compound with a molecular weight of 125 and Is  water soluble, it is conjugated with bile acids.

3.Taurine biosynthesis

The biosynthesis of taurine theoretically  linked to the metabolism of sulfur amino acids, involving the enzymatic oxidation and conversion of dietary cystein derived either directly or via conversion from methionine.

Taurine synthesis occurs mainly in the liver and brain. The major pathway for taurine biosynthesis in mammalian tissues is : methionine –> cysteine –> cysteinesulfinic acid –> hypotaurine –> taurine, and requires several enzymes.  Cystathionine synthase, cystathionase and cysteinesulphinic acid decarboxylase are the three involved enzymes, all of which require vitamin B6 as a co-factor; vitamin B6 deficiency, due to poor intake, drug antagonism or disease-altered metabolism, reduce taurine synthesis. The activity of the hepatic rate-limiting enzyme cysteinesulphinic acid decarboxylase (CSAD) is influenced by age and sex. Humans have a relatively low enzyme activity, and especially in neonate the enzyme activity is the lowest, and it facing the  risk of taurine deficiency. The fetus and newborn are dependent upon to a great extent for their supply of taurine. In general, men have a higher enzymatic activity than women, a phenomenon that may explain the higher incidence of gallstones in women, as taurine involved in bile acid conjugation (Hayes. 1981, Lourenço. 2002).

Within the nervous system, taurine synthesis is restricted to the cell body and nerve terminals, since no CSAD activity is present in axons.

Thyroxin decreases CSAD activity, possibly by depressing CSAD synthesis: and experimentally induced hypothyroidism results in increased concentrations of taurine in brain, which are corrected by thyroxin. In contrast, hydrocortisone increases CSAD activity, although the same hormone decreases taurine conjugation of bile acids by human fetal liver in vitro.

To see the diagram of Taurine  synthesis, click –> Taurine synthesis

3.Physiological roles

Taurine is conjugated via its amino terminal  group with its chenodeoxycholic acid and cholic acid to form the bile salts sodium taurocholate. The low pKa (1.5) off taurine’s sulfonic acid group ensures that this moiety is negatively charge in the pH ranges normally found in the intestinal tract and thus improves the surfactant properties of the cholic acid conjugate.

Taurine also appears to have a stabilizing effect on cell membranes and is important in maintaining normal extra- and intracellular distribution of calcium.  This in turn has implications on neuronal excitability and the regulation of osmotic pressure.

In the central nervous system taurine involves in the cell regulation and inhibitory neuromodulation or neurotransmission. As a neurotransmitter taurine should have a specific receptors in the post synaptic  membrane.

Taurine as an antioxidant in cell protection. Immunohistochemical study showed that taurine administration suppressed the intensified staining to the three different types of oxidative stress markers, such as 8-hydroxyl-2’deoxyguanosine (8-OHdG), pentosidine, and nitrotyrosine observed in the renal tissues of untreated diabetic rats. This finding suggest that taurine has the ability to suppress the progression of diabetic nephropathy at least in the part by its antioxidant property. In other study, streptozotocin induced diabetic rats showed lower progression in proteinuria having taurine in their drinking water compare with controlled group.

Many clinical and animal study (ref.3) on effect of taurine supplement on congestive cardiac failure showed inhibition of progression on heart failure. According to one animal study taurine reduce mortality rates as compared to controls, improve the animals’ clinical condition, hemodynamic and myocardial contractility parameters. Taurine was also found to exert a positive action on the heart response to stresses. In one of clinical trial, a double-blind, randomized, crossover, placebo-controlled study, investigation of the effects of adding taurine to the conventional treatment in 14 patients with congestive heart failure for a 4-week period. Compared with placebo, taurine significantly improved the New York Heart Association functional class, improving the pulmonary sound (pulmonary crackles), and chest film abnormalities. The author concluded that addition of taurine to conventional therapy of heart failure is safe and effective.

In experimental diabetic neuropathic rats was shown that taurine can improve (and possibly reverse) the defects in nerve blood flow, and motor nerve sensory thresholds.

According to some animal studies, taurine produced an anxiolytic-like effect in mice and may act as a modulator or anti-anxiety agent in the central nervous system.

In recent years, taurine has become a common ingredient in energy drink. In energy drinks taurine often used with vitamin B complex and caffeine. Precaution should be taken especially for older age, for the caffeine can increase heart rate and blood pressure.

Sometime taurine used in combination with body building supplements such as creatine and anabolic steroids, probably due to the findings in experimental mice that taurine alleviates muscle fatigue and raises capacity in strenuous muscle exercise.

4.Sources

Taurine is regarded as a conditionally-essential amino sulfonic acid, because it can be synthesized by the body from the other sulfur-containing amino acids cysteine and methionine.  Taurine is essential for infants where it plays important roles in the development of the nervous system, retina, and muscle tissue.

There is no information available to date how much our requirement of taurine. Adult  human  vegetarians  have not  been reported  to  suffer from  taurine  depletion,  but  more  extensive  examination and documentation of their  taurine status  is  desirable (K.C.Hayes, 1981).

As supplement taurine  in 500 mg capsule is availabel.

Information abaut taurine content of food as you see in the two table below:

Food                                                      Taurine content

1.Animal foods

Poultry                                 89-2245 µmol/100 g wet weight

Beef and pork                   307-489 µmol/100 g wet weight

Processed meats             251-981 µmol/100 g wet weight

Sea food                              84-6614 µmol/100 g wet weight

Cow’s milk                          18-20 µmol/100 ml

Yogurt, ice cream             15-62 µmol/100 ml

2.Plant food

Soy bean, some nuts      < 1- 4 µmol/100 ml

(M.E. Shils, Modern nutrition in health and diseases)

 

Other availabel tabel (R. Lourenço and M. E. Camilo, 2002)

Meat
Beef/raw . . . . . . . . . . . . . . . . . . . . . 43
Pork/raw . . . . . . . . . . . . . . . . . . . . . 61
Chicken/raw dark meat . . . . . . . . . . 169
Turkey/raw dark meat . . . . . . . . . . . 306
Lamb/raw dark meat . . . . . . . . . . . . 47
Ham/baked . . . . . . . . . . . . . . . . . . . 50
Seafood
Tuna/canned . . . . . . . . . . . . . . . . . . 42
White fish/raw . . . . . . . . . . . . . . . . . 151
Mussels/raw . . . . . . . . . . . . . . . . . . 655
Oysters/fresh . . . . . . . . . . . . . . . . . . 70
Cod/frozen . . . . . . . . . . . . . . . . . . . 31
Clams/fresh . . . . . . . . . . . . . . . . . . . 240
Clams/canned . . . . . . . . . . . . . . . . . 152
Milk and derivatives
Pasteurized milk . . . . . . . . . . . . . . . 6
Cheddar cheese . . . . . . . . . . . . . . . . not detected
Yogurt/low fat plain . . . . . . . . . . . . 3.3
Ice cream/vanilla . . . . . . . . . . . . . . . 1.9
Fruit, vegetables, seeds, nuts,  . . . . .
grain, beans peanuts, cereals  . . . . . not detected
Taurine content is expressed in mg (mean)/100 g wet weight.

References

  1. K.  C.  Hayes: Ann. Rev.  Nutr. 1981.  1:401-25
  2. R. Lourenço and M. E. Camilo Nutr. Hosp. (2002) XVII (6) 262-270
  3. www.supplementwatch.com (Taurine overview)
  4. http://www.thorne.com/altmedrev/.fulltext/6/1/78.pdf monograph
  5. http://www.lef.org/abstracts/codex/taurine_index.htm
  6. http://en.wikipedia.org/wiki/Taurine
  7. http://www.ncbi.nlm.nih.gov/pubmed/12514918
  8. http://findarticles.com/p/articles/mi_m0FDN/is_1_6/ai_71948215/pg_3/ Alzheimer’s Disease alternative med
  9. http://www.sage-hindawi.com/journals/jaa/2010/346237.html pharmacokinetic

( The above files was download between July 2007 – August 2010)