DRINKING just one can of the popular Red Bull energy drink may be enough to increase dramatically the risk of developing life-threatening blood clots, even in healthy young people.

Despite the drinks' promotional promise to give its customers "wings", Australian researchers who studied the caffeine-laden beverage say it may also increase the risk of symptoms commonly associated with heart disease.

Scott Willoughby, from the Cardiovascular Research Centre at the Royal Adelaide Hospital, said the study showed "that normal people develop symptoms normally associated with cardiovascular disease" after drinking Red Bull.

The results were such that he would not drink Red Bull himself, he said.

Dr Willoughby tested the cardiovascular systems of 30 young adults - Red Bull's target demographic - one hour before and one hour after consuming one 250ml can of sugar-free Red Bull.

He said the results were striking: "One hour after they drank Red Bull, (their cardiovascular systems) were no longer normal. They were abnormal like we would expect in a patient with cardiovascular disease."

Particular attention was paid to the various factors that result in the formation of blood clots, Dr Willoughby said, including stickiness of the blood and the proper functioning of the patient's blood vessels.

"If you get an increase in stickiness and a decreased ability of the blood vessels to stop its stickiness, that adds up to a bad situation," he said.

"If you add in other risk factors for cardiovascular disease - stress or high blood pressure - this could be potentially deadly."

He said these and other factors, such as the effects of Red Bull when mixed with alcohol, would be the subject of further studies.

While Red Bull is already banned in countries such as Norway and Denmark, Dr Willoughby said there would have to be further research before it could be banned in Australia.

"The can currently comes with a warning of its own," he said. "But if you have any predisposition to cardiovascular disease, I'd think twice about drinking it."

Red Bull Australia spokeswoman Linda Rychter said she had spoken to Dr Willoughby and had asked to be sent a copy of the paper and could not comment on its findings until they had been assessed by the head office in Austria.

Red Bull is particularly popular among university students, who often drink numerous cans of the beverage at exam time or when studying. It was a group of Dr Willoughby's undergraduate students who originally came up with the idea for the study.

MATTHEW CLAYFIELD

theaustralian.com.au/