Humor Urban Legends Do Energy Drinks Contain Bull Sperm? What is the truth about taurine? Share PINTEREST Email Print George Rose/Getty Images Urban Legends Rumors & Hoaxes Urban Legends in the News Classic & Historic Legends Animal Folklore Scary Stories By David Emery David Emery is an internet folklore expert, and debunker of urban legends, hoaxes, and popular misconceptions. He currently writes for Snopes.com. our editorial process David Emery Updated January 24, 2019 According to online rumors, Red Bull, Monster, Rockstar and other brand-name energy drinks contain a secret ingredient to pep you up: bull semen. As it happens, there is an ingredient in most energy drinks called taurine. But is it really made using an extract from bull testicles? This is a false internet rumor that's been circulating since 2001. Despite longstanding rumors to the effect that top-selling energy drinks such as Red Bull, Rockstar, and Monster contain unlisted ingredients such as bull sperm, bull urine, and/or testosterone extracted from bull testicles, there is no truth to any of these claims. What Is Taurine? Where did people get the idea that there is bull semen in their energy drinks? It was apparently inspired by the fact that all of these beverages do contain taurine. The word taurine is derived from Taurus, which is Latin for bull (Taurus the Bull is one of the signs of the zodiac). Taurine is a sulfur-containing amino acid which plays a role in the metabolism of fats. Taurine occurs naturally in all fish and animal tissues (including human tissues); it is so important to human functioning that it is included as an ingredient in baby formula (infants' bodies can't yet produce taurine, which is provided through breast milk). Taurine is also used to treat a wide range of disorders including congestive heart failure, high blood pressure, and diabetes. Does Taurine Come from Bull Semen? It may seem odd to name an amino acid after a mythical bull, but there is logic behind the choice of name. The first time scientists managed to isolate the amino acid it was from a specimen of ox bile. Ox bile isn't bull semen; it's an acidic substance produced by the gallbladder. Ox bile is still an unpleasant-sounding substance, perhaps even more so than bull semen. But if that's still worrisome to anyone, rest easy: the taurine used in Red Bull and other energy drinks is completely synthetic. It's not made from animal tissues of any kind; in fact it is an ingredient suitable for vegans. Why Do Energy Drinks Include Taurine? Taurine is added to Red Bull and other sodas to make good on the name "energy drink." Some studies have suggested that taurine may improve athletic performance and can even, combined with caffeine (another ingredient found in these products), improve mental acuity. The World Anti-Doping Agency does not ban taurine, which suggests that any performance-enhancing qualities are very mild. Further research needs to be done to confirm that taurine provides these specific health benefits. According to the Mayo Clinic, up to 3,000 mg of supplemental taurine per day is considered safe for human consumption. Energy drinks typically contain around 1,000 mg per serving (one 8.4-ounce can, in the case of Red Bull). Some doctors warn that energy drinks should be consumed in moderation, but that's mainly due to their high caffeine content, not because there's any danger of a bull semen overdose. While taurine occurs naturally in the body and is not considered to be a dangerous supplement, it is important to limit intake of taurine as some studies suggest overdosing can have negative impacts.