The increasingly popular high-caffeine beverages called energy drinks may do more than give people a jolt of energy -- they may also boost heart rates and blood pressure.
The drinks generally have high levels of caffeine and taurine, an amino acid that can affect heart function and blood pressure.
"We saw increases in both blood pressure and heart rate in healthy volunteers who were just sitting in a chair watching movies. They weren't exercising. They were in a resting state," James Kalus of Henry Ford Hospital in Detroit, who led the study, said in an interview.
The increases did not rise to dangerous levels in the group of 15 healthy volunteers, whose average age was 26, the researchers said. But the increases potentially could be significant in people with cardiovascular disease, they said.