Reports in the media of a New Zealand woman's extreme Red Bull diet where her weight plummeted from 105kg to 60kg by drinking 10 to 14 cans of the 'energy' drink each day say she has been left with serious health issues.
Red Bull which was first launched in Austria in 1987 is so-called after the ingredient taurine, the organic acid which was first isolated in a bull; it is prohibited as a soft drink in Norway, Uruguay, Denmark and Iceland - the formula contains the same amount of caffeine as a cup of filter coffee, around 80mg and has benefited from much 'pop' and sport celebrity endorsement - the sugar-free version of the drink was launched in 2003.
Brooke Robertson a 23-year-old Auckland mother says she lost 45kg in eight months by drinking nothing but Red Bull with a handful of dry cereal each day but now has ongoing health problems because of the diet.
Ms Robertson says her weight gain occurred while she was pregnant with her son Keir, now four and says she did not make a conscious decision to go on a Red Bull diet but found it was an appetite suppressant and as she was losing weight she continued to drink it.
The habit became an addiction which she hid from family and friends but it led to a minor heart attack and a two-week enforced stay in hospital. Ms Robertson says she suffered severe withdrawal symptoms such as sweating, nausea, and shaking and doctors realised she had an addiction, which has left her with a heart murmur, severe pain and cramping in her stomach and bowel and anxiety attacks.
A Red Bull spokesman said there was "scientific evidence that caffeine is not addictive" and the drink was available in 148 countries "because health authorities across the world have concluded that Red Bull is safe to consume" - but the drink is banned in Norway, Denmark and Uruguay because of health fears.
Last year research from both Australia and the United States questioned the safety of energy drinks such as Red Bull and suggested they could be harmful to some people.
The researchers say high-caffeine energy drinks may provide more than an energy boost as they may also boost heart rates and blood pressure levels and increase the danger of blood clots.
The results of a small study by researchers from Detroit's Henry Ford Hospital has found that the high levels of caffeine and taurine, an amino acid found in protein-rich foods like meat and fish, can affect heart function and blood pressure and they say people who have high blood pressure or heart disease should avoid energy drinks because they could have an impact on their blood pressure or change the effectiveness of their medications.
Dr. James Kalus who led the study, says increases were seen in both blood pressure and heart rate in 15 healthy volunteers with an average age of 26, who were resting and not exercising and while the increases did not rise to dangerous levels in the group they could be significant in people with cardiovascular disease or those taking drugs to lower heart rate or blood pressure.
The energy drinks included Red Bull, Full Throttle, Amp and Rush.
For the study the group were asked not to consume other forms of caffeine for two days before and throughout the study in which they consumed two cans of energy drinks daily over seven days, each can containing 80 milligrams of caffeine and 1,000 milligrams of taurine.
The volunteers' heart rates rose by about 8 percent on the first day and 11 percent on the seventh day - systolic blood pressure rose by 8 percent on the first day and 10 percent on the seventh day, and diastolic blood pressure rose by 7 percent on the first day and 8 percent on the seventh day.
The researchers suggest the caffeine and taurine in the drinks were responsible for the changes.
Australian researchers from the Royal Adelaide Hospital say they have found that the sugar-free version of Red Bull may increase the danger of blood clots; they say it creates "sticky" blood, raising the risk of heart attack or stroke and warn that the drink "could be deadly" for people with heart abnormalities.
Lead researcher Dr. Scott Willoughby says though the incidence of sudden cardiac death is very low, the drink could be more deadly for people who have an unknown cardiovascular abnormality.
Sales of Red Bull last year reached 3.5 billion cans, sold in 143 countries.