Red Bull may claim to “give you wings” but drinking too much of the popular energy drink may also lead to heart damage, a study suggests.

A 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,” he said. “People who already have existing cardiovascular disease may want to talk to their physician before they drink Red Bull in future.”

Previous studies have examined the effects of consuming Red Bull, one can of which contains 80mg of caffeine — around the same as a cup of filter coffee — and taurine, an amino acid commonly used in energy drinks.

An estimated 330 million litres of energy drinks were consumed in Britain last year, a market worth £1 billion. However Red Bull is banned in countries such as Norway, Uruguay and Denmark because of health fears.

Last year a research team from Henry Ford Hospital in Detroit presented a paper to the American Heart Association suggesting that energy drinks may boost heart rates and blood pressure levels. The results, from a small study, prompted them to warn against consumption by those with cardiovascular problems.

Earlier this year a teenager from Darlington was sent to hospital after drinking eight cans of Red Bull. Paramedics reported that the 15-year-old suffered heart palpitations.

Last year a large study of American college students found that those who drank energy drinks mixed with alcohol during a night out were twice as likely to be injured or otherwise come to harm than those who consumed alcoholic drinks on their own.

Dr Willoughby said that he was prompted to conduct the study after recent reports of deaths in young people who had consumed large amounts of the energy drink before they died.

The high levels of caffeine in Red Bull was suspected to be a contributing factor in the death of a 40-year-old man in Oxford who suffered a fatal heart attack in April after collapsing at an Asda store where he worked. In 2007 an 18-year-old British basketballer died after consuming three cans of the drink, and in July 2001 and 33-year-old Australian man died of a heart attack after drinking a pitcher of Red Bull and vodka.

“There was enough anecdotal evidence to catch my attention,” Dr Willoughby said. He added that previous studies had shown caffeine and taurine to have an effect on blood platelets and heart function, sometimes with beneficial results, such as boosting endurance while exercising.

But, he added, “maybe there’s something quirky about the effect of the combination of the two in the drink which is causing this reaction, this is what we need to look at next.”

The results shocked the 30 students, some of whom drank up to eight cans a night to help them stay awake to study, and many now refuse to consume the energy drink again. Dr Willoughby said he now aims to extend this preliminary study to a larger group of students to verify the results.

Linda Rychter, a spokeswoman for Red Bull in Australia, said that the report would be assessed by the company’s head office in Austria. “The study does not show effects which would go beyond that of drinking a cup of coffee. Therefore, the reported results were to be expected and lie within the normal physiological range,” she added.

Red Bull, which has the catchphrase “Red Bull gives you wings”, was created in Austria in the 1980s. The company last year sold 3.5 billion cans of the drink in 143 countries. Cans of Red Bull already carry health warnings advising customers not to drink more two cans a day.

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