A sulphur-containing amino acid, taurine has a number of biochemical roles in human metabolism. The amino acid was first named for the Latin Taurus, which means bull or ox, because it was first described in ox bile by a German scientist in 1827.1 Taurine is one of the major ingredients in most of the common energy drinks, and concerns over the safety of these drinks and questions as to the ingredients’ role in human cellular function have sparked renewed interest in this compound.
Like several other amino acids, taurine is often not found in its functional state in foods. However, it is a derivative of cysteine, which is another, more widely occurring amino acid. Taurine has multiple roles in the body, including membrane stabilization, calcium signaling, and regulation of cardiac and skeletal muscle function; it is also a potent antioxidant.2 As a result of these functions, taurine is thought to influence blood pressure, cardiac muscle function, liver function, and exercise tolerance.
Because of its role in energy drinks, interest in taurine has grown. Consumption of energy drinks, which are marketed under a wide variety of brands and names, has increased dramatically in the last few years. One source quotes a 240% increase in sales from 2004 to 2009 with the brand Red Bull, claiming that more than 4 billion units were sold worldwide in 2011.3
Of the popular energy drinks available today, the major ingredients are sugar, caffeine, and taurine. Taurine concentrations in these drinks are usually between 1,000 mg and 2,000 mg per serving, with some brands containing as much as 3,000 mg to 4,000 mg per serving. Consumers’ claims of increased alertness and endurance were initially attributed to the caffeine content of the energy drinks. However, studies are finding that the effects of the ingredients in these drinks, especially caffeine and taurine, are more synergistic, bringing into play the effect of taurine.4
In a small study of healthy college-aged volunteers in which participants were randomly assigned to placebo or daily intake of a standardized energy drink, researchers evaluated the effect of the ingredients in the energy drinks on designated behavioral tasks that involve motor skills, judgement, and stamina.4 The findings of the study were somewhat vague, however, it appeared that taurine attenuated the effects of caffeine, thereby moderating the ‘buzz’ typically reported with heavy caffeine intake but extending its effects of increased concentration and energy.
Taurine also plays a significant role in skeletal and cardiac muscle contractility, making it important in the management of most cardiovascular functions. These functions are of a protective nature due to taurine’s calcium channel blocking function.5 This same action controls hypertension at the vascular level by reducing vasoconstriction and decreases the incidence of cardiac arrhythmias.
In a small but compelling study, researchers found improvements in exercise and metabolic measures after 2 weeks of oral supplementation with taurine.6 Researchers enrolled 29 patients with left ventricular ejection fractions (LVEFs) of less than 50% who were categorized as Class II or III by the New York Heart Association Functional Classification.6 Study participants were randomly assigned to protocols of either oral taurine supplementation or placebo. Each patient was evaluated at the beginning of the two-week trial and at the end with a standardized or modified Bruce exercise tolerance test and for LVEFs and metabolic equivalents (METS). In the group receiving taurine supplements, results after 2 weeks were statistically significant across all measures, most notably for an increase of 20% in distance achieved with the Bruce exercise tolerance test and of 30% in METS, in comparison with placebo groups.
Taurine has also been found to have a role as an antioxidant. Another small study of healthy young men evaluated the pre- and post-exercise plasma levels of thiobarbituric-acid-reactive substances (TBARS), which can serve as an indicator of oxidative cell damage.7 The participants performed a session of ergometric exercise on bicycles until exhaustion. Plasma levels of taurine and TBARS had inverse correlations in the pre-exercise group. Then, the participants underwent a 7-day course of taurine supplementation and repeated the exercise routine. Following the supplementation and exercise, there were statistically significant increases in exercise time to exhaustion and maximal workload, correlating with at reduced serum TBARS level.7