Their rising popularity represents a generational shift in what people drink, and reflects a successful campaign to convince consumers, particularly teenagers, that the drinks provide a mental and physical edge.
The drinks are now under scrutiny by the Food and Drug Administration after reports of deaths and serious injuries that may be linked to their high caffeine levels. But however that review ends, one thing is clear, interviews with researchers and a review of scientific studies show: the energy drink industry is based on a brew of ingredients that, apart from caffeine, have little, if any benefit for consumers.
“If you had a cup of coffee you are going to affect metabolism in the same way,” said Dr. Robert W. Pettitt, an associate professor at Minnesota State University in Mankato, who has studied the drinks.
Energy drink companies have promoted their products not as caffeine-fueled concoctions but as specially engineered blends that provide something more. For example, producers claim that “Red Bull gives you wings,” that Rockstar Energy is “scientifically formulated” and Monster Energy is a “killer energy brew.” Representative Edward J. Markey of Massachusetts, a Democrat, has asked the government to investigate the industry’s marketing claims.
Promoting a message beyond caffeine has enabled the beverage makers to charge premium prices. A 16-ounce energy drink that sells for $2.99 a can contains about the same amount of caffeine as a tablet of NoDoz that costs 30 cents. Even Starbucks coffee is cheap by comparison; a 12-ounce cup that costs $1.85 has even more caffeine.
As with earlier elixirs, a dearth of evidence underlies such claims. Only a few human studies of energy drinks or the ingredients in them have been performed and they point to a similar conclusion, researchers say — that the beverages are mainly about caffeine.
Caffeine is called the world’s most widely used drug. A stimulant, it increases alertness, awareness and, if taken at the right time, improves athletic performance, studies show. Energy drink users feel its kick faster because the beverages are typically swallowed quickly or are sold as concentrates.
“These are caffeine delivery systems,” said Dr. Roland Griffiths, a researcher at Johns Hopkins University who has studied energy drinks. “They don’t want to say this is equivalent to a NoDoz because that is not a very sexy sales message.”
A scientist at the University of Wisconsin became puzzled as he researched an ingredient used in energy drinks like Red Bull, 5-Hour Energy and Monster Energy. The researcher, Dr. Craig A. Goodman, could not find any trials in humans of the additive, a substance with the tongue-twisting name of glucuronolactone that is related to glucose, a sugar. But Dr. Goodman, who had studied other energy drink ingredients, eventually found two 40-year-old studies from Japan that had examined it.
In the experiments, scientists injected large doses of the substance into laboratory rats. Afterward, the rats swam better. “I have no idea what it does in energy drinks,” Dr. Goodman said.
Energy drink manufacturers say it is their proprietary formulas, rather than specific ingredients, that provide users with physical and mental benefits. But that has not prevented them from implying otherwise.
Consider the case of taurine, an additive used in most energy products.
On its Web site, the producer of Red Bull, for example, states that “more than 2,500 reports have been published about taurine and its physiological effects,” including acting as a “detoxifying agent.” In addition, that company, Red Bull of Austria, points to a 2009 safety study by a European regulatory group that gave it a clean bill of health.
But Red Bull’s Web site does not mention reports by that same group, the European Food Safety Authority, which concluded that claims about the benefits in energy drinks lacked scientific support. Based on those findings, the European Commission has refused to approve claims that taurine helps maintain mental function and heart health and reduces muscle fatigue.
Taurine, an amino acidlike substance that got its name because it was first found in the bile of bulls, does play a role in bodily functions, and recent research suggests it might help prevent heart attacks in women with high cholesterol. However, most people get more than adequate amounts from foods like meat, experts said. And researchers added that those with heart problems who may need supplements would find far better sources than energy drinks.
Hiroko Tabuchi contributed reporting from Tokyo and Poypiti Amatatham from Bangkok.
