The study of 30 university students aged between 20 and 24 years old found that drinking just one 250ml sugar-free can of the caffeinated energy drink increased the "stickiness" of the blood and raised the risk of blood clots forming.
Using tests to measure blood pressure and the state of blood vessels around the body, the Australian researchers said that after drinking one can participants had shown a cardiovascular profile similar to that of someone with heart disease.
Red Bull today emphatically denied that the drink, which is distributed to 143 countries worldwide, was dangerous. In a statement, it said that Red Bull had been proved safe by "numerous scientific studies", and that it had never been banned from anywhere it had been introduced.
Scott Willoughby, of the Cardiovascular Research Centre at the Royal Adelaide Hospital and Adelaide University, said that he was alarmed at the results, and suggested that older adults who already have symptoms of heart disease should refrain from drinking too much of the energy drink.
"After one can it seemed to turn the young individual into one with more of the type of profile you would expect to see with someone with cardiovascular disease," TimesOnline quoted him, as saying.
"People who already have existing cardiovascular disease may want to talk to their physician before they drink Red Bull in future," he added.