The caffeine-loaded beverage, popular with university students, caused the blood to become sticky, a pre-cursor to cardiovascular problems such as stroke.
'One hour after they drank Red Bull, (their blood systems) were no longer normal. They were abnormal like we would expect in a patient with cardiovascular disease,' Scott Willoughby, from the Cardiovascular Research Centre at the Royal Adelaide Hospital said.
Willoughby and his team tested the cardiovascular systems of 30 young adults one hour before and one hour after consuming one 250ml can of sugar-free Red Bull.
The results showed 'normal people develop symptoms normally associated with cardiovascular disease' after consuming the drink.
Red Bull was created in the 1980s by Austrian entrepreneur Dietrich Mateschitz based on a similar Thai energy drink.
It is banned in Norway, Uruguay and Denmark because of health risks listed on its cans, but the company last year sold 3.5 billion cans in 143 countries.
One can contains 80 mg of caffeine, around the same as a normal cup of brewed coffee.
The Austria-based company, whose marketing says 'Red Bull gives you wings', sponsors Formula 1 race cars and extreme sport events around the world, but warns consumers not to drink more than two cans a day.
Willoughby said Red Bull could be deadly when combined with stress or high blood pressure, impairing proper blood vessel function and possibly lifting the risk of blood clotting. (The Daily Mail Friday 15th August 2008)