I see taurine listed as an ingredient in energy drinks. What is it?
| Response from Gayle Nicholas Scott, PharmD
Assistant Professor, Eastern Virginia Medical School, Norfolk, Virginia; Clinical Pharmacist, Chesapeake Regional Medical Center, Chesapeake, Virginia
Taurine was isolated in the early 19th century from ox bile; its name is from the Latin word for ox or bull. Taurine is a conditionally essential amino acid, classified between essential amino acids that the body cannot produce (eg, lysine, tryptophan) and nonessential amino acids that the body can produce (eg, alanine, cysteine). Taurine is synthesized in the liver and brain via cysteine or methionine. This process requires several enzymatic steps, all of which require vitamin B6 as a cofactor. Taurine is considered conditionally essential because it cannot be synthesized by infants younger than 4-6 weeks, and it may not be adequately synthesized in patients receiving long-term parenteral nutrition and patients with short-term hypermetabolic conditions (eg, multiple trauma). Brain, heart, and skeletal muscle tissue contain high concentrations of taurine.
Animal products are the primary dietary source of the ingredient; vegetables contain virtually no taurine. Vegetarians may have lower plasma concentrations of taurine than meat-eaters. Taurine is present in high concentrations in human breast milk and in much lower concentrations in cow milk. Energy drinks (eg, Red Bull, Rockstar, Monster) typically contain 1 g of taurine per 8 oz.
Interest in taurine as an exercise supplement was piqued by research suggesting that taurine might be released from muscle during exercise. Additional research found that 6 g of taurine/day for 7 days could enhance exercise capacity possibly via antioxidant effects. However, subsequent studies of taurine supplementation with 5 g/day for 7 days found no change in muscle taurine content and no effect on muscle metabolism during exercise. Taurine 1.66 g taken 1 hour before 90 minutes of submaximal exercise had no effect on time trials in endurance-trained cyclists.
More recent research on taurine with caffeine showed that this combination restored performance of sleep-deprived surgeons on simulated laparoscopy, making them feel more alert but not reducing errors. The influence of caffeine on these results was unclear. Giles and colleagues compared the effects of caffeine 200 mg, taurine 2 g, a combination of these, and placebo on the cognitive performance of 48 habitual caffeine users. Caffeine, but not taurine, appeared to be responsible for improved cognitive performance. Some research suggests that taurine in combination with branched chain amino acids may reduce muscle soreness and muscle damage after high-intensity exercise.
The increasing popularity of energy drinks, which typically include taurine, has prompted multiple studies about their effect on exercise. The studies were small (the largest had a sample size of 20), included athletes or physically active adults as subjects, and most commonly tested Red Bull against placebo.[14,15,16,17,18,19,20,21] A 250-mL can of Red Bull contains taurine 1 g, caffeine 80 mg, glucuronolactone (a glucose metabolite) 600 mg, B vitamins, and is available with and without sugar. Some studies showed modest improvements in endurance,[16,19,21] but others found no effect.[14,15,17,20] A study sponsored by Red Bull found improved driving performance and reduced driver sleepiness compared with placebo in 24 healthy volunteers. A recent study in which subjects were given coffee containing 80 mg of caffeine or decaffeinated coffee showed that caffeinated coffee improved driving performance and reduced driver sleepiness in simulated driving. Some experts suggest that caffeine is the likely ingredient responsible for enhanced physical or cognitive effects of energy drinks.[4,18]
Energy drinks that include taurine as an ingredient have also had detrimental effects reported,[24,25] as have numerous case reports, often in patients with high consumption.[26,27,28,29,30,31] A study of platelet and endothelial function in 50 healthy young males found increased platelet aggregation and decreased endothelial function 1 hour after consumption of 250 mL of an unspecified energy drink containing caffeine 80 mg, taurine 1 g, glucuronolactone 600 mg, and B vitamins. Another group of researchers compared a single, 250-mL can of Red Bull vs a compounded drink containing only 240 mL bottled water and caffeine 80 mg. Red Bull increased mean 24-hour and mean daytime blood pressure compared with caffeine, suggesting that the caffeine in Red Bull is not solely responsible for hemodynamic effects.
The International Society of Sports Nutrition position statement on energy drinks cites the need for additional research on supplements such as taurine to sort out the effects of caffeine vs other ingredients. The World Anti-Doping Agency does not include taurine on its list of banned substances, implying that available evidence does not support significant energy-enhancing properties of taurine.
Most available research on taurine is in combination with caffeine and other ingredients. Taurine has been used safely for up to 1 year in patients with heart failure. On the basis of available research, the effect of taurine on cognitive and physical ability is unclear. Taurine appears to be safe for most people, but energy drinks should be used with discretion.
Medscape Pharmacists © 2013 WebMD, LLC
Cite this: Taurine in Energy Drinks: Backed by Research or Just Bull? - Medscape - May 14, 2013.