Taurine is an organic acid produced in the pancreas of humans. Taurine is not a true amino acid because although it is an acid and does contain an amino group, it does not contain a carboxyl group, However, colloquially taurine is often referred to as an amino acid. Taurine is found naturally in the diet where is occurs in seafood, dairy products and meat. Because taurine is not found in vegetable proteins, vegetarians who exclude eggs and milk may consume lower amounts of taurine. Taurine is a constituent of bile and is therefore present in the large intestine. However taurine is particularly concentrated in the nervous tissue and platelets. Taurine has become popular as a sports supplement because it is thought to modulate neuromuscular excitation through regulation of calcium influx and may therefore be necessary for correct muscle function. Evidence also suggests that taurine is beneficial to the cardiovascular system and may reduce blood pressure.
Taurine may regulate production of cellular oxidation and lead to the modulation of certain eicosanoids, including thromboxane. This has lead to suggestions that it may alter platelet aggregation and affect blot clotting. Some studies have investigated the effects of taurine supplements in humans and found modulatory effects on platelet aggregation. For example, one group of researchers1 supplemented human subjects with either 400 or 1600 mg per day taurine and measured the ability of the platelets to resist aggregation using a biochemical test. The results showed that at the 400 mg per day doses, platelet aggregation was reduced by 30 %, but at the 1600 mg per day platelet aggregation was reduced by 70 %. The decrease in platelet aggregation was associated with increased taurine and glutathione concentrations as well as a decrease in thromboxane release upon assessment of aggregation.
In this study taurine supplementation with 400 mg per day increased plasma taurine levels by 55 % whereas the higher 1600 mg per day intake increased plasma taurine by 115 %. However, the authors reported that platelet taurine concentration was a better predictor of platelet function than the plasma taurine concentration. The authors also used cat collagen ex vivo to show that platelet aggregation was more sensitive in cats depleted of taurine compared to those with normal taurine status. Therefore taurine may modulate platelet aggregation in humans and other mammals and taurine deficiency may increase the susceptibility of platelets to aggregate. However, because taurine is naturally produced in the pancreas and is not essential in man, the significance of these results is not known. In addition, taurine is considered an essential amino acid for cats, and so these results should be treated with caution.
Therefore supplements of taurine may be beneficial to the cardiovascular system in terms of reducing platelet aggregation, especially when considering that blood pressure lowering effects have also been reported. It is not known why taurine decreases platelet aggregation but it may relate to the ability of taurine to raise platelet glutathione concentrations, which increases the redox capacity of the platelets and decreases their sensitivity to clot. Evidence for this line of reasoning comes from diabetics who have low glutathione concentrations in platelets and this gives them a high propensity to clot. How taurine can increase platelet concentrations of glutathione is also not fully understood, but the ability of taurine to act as an in vitro antioxidant suggests that it may spare glutathione and thus increase plasma and platelet levels. High urinary losses of taurine can occur through stress and intestinal problems, and excessive alcohol consumption can prevent the body from correctly utilising taurine. Diabetes also increases the requirement for taurine.
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