"However in most of the cases we looked at for our review, caffeine intoxication was thought to play the most important role. This has been borne out by case studies that focus on other products that contain high levels of caffeine but no glucose or fructose.

"Despite this, caffeine free cola products can also cause hypokalaemia because the fructose they contain can cause diarrhoea."

The authors argue that in an era when portion sizes are becoming bigger and bigger, the excessive consumption of cola products has real public health implications.

"Although most patients recover when they stop drinking cola and take potassium supplements, cola-induced chronic hypokalaemia can make them more susceptible to potentially fatal complications, such as an irregular heartbeat" says Dr Elisaf.

"In addition, excessive consumption of any kind of cola can lead to a range of health problems including fatigue, loss of productivity and muscular symptoms that vary from mild weakness to profound paralysis.

"We believe that further studies are needed to establish how much is too much when it comes to the daily consumption of cola drinks."

Dr Packer agrees that the problem needs to be addressed.

"Cola drinks need to be added to the physician's checklist of drugs and substances that can cause hypokalaemia" he says.

"And the soft drink industry needs to promote safe and moderate use of its products for all age groups, reduce serving sizes and pay heed to the rising call for healthier drinks."

ijcp