Causes, effects debated

The FDA, which quashed the controversial practice of manufacturers including caffeine in alcoholic drinks such as Four Loko by issuing warning letters to four companies in 2010, has not acted on petitions by academics and other experts to limit caffeine or change labeling requirements for energy drinks. "Those petitions are still within the FDA and still under consideration, and the agency can't comment," said Susan Carlson of the FDA's office of food additive safety. Nationally, emergency room visits associated with energy drink use increased more than tenfold from 1,128 in 2005 to 13,114 in 2009, according to a report released last month by the federal government's Substance Abuse and Mental Health Services Administration. UGG Boots Outlet Forty-four percent involved combinations with other substances such as alcohol, pharmaceuticals or illicit drugs, which the American Beverage Association said made energy drink consumption "potentially irrelevant." However, more than half of the visits didn't involve another substance. Most adverse reactions involve people who consumed two to eight energy drinks or more than 200 milligrams of caffeine, said Higgins, co-author of the Mayo Clinic report. The exhaustive review of studies on energy beverages by Higgins and Houston exercise physiologist Troy D. Tuttle noted the risk of such effects as insomnia, nervousness, nausea, rapid heartbeat — and in more rare cases, seizures, cardiac arrhythmias and cardiac arrest, particularly in people with underlying medical conditions. The review also cited four documented cases of caffeine-associated deaths involving individuals who had consumed energy drinks. "For a healthy person, probably one is not going to kill you. But we don't know," Higgins said. "I think it's the combination of things in these energy beverages," he added, cautioning about interactions. "A lot of athletes drink coffee."