Study cites case of otherwise fit and healthy man in his 50s who had a stroke after eight-drink-a-day habit

Millions of people worldwide regularly drink the products, which are non-alcoholic and typically contain more than 150mg of caffeine per litre, very high glucose-based sugar content and varying quantities of other chemicals.

Doctors in Nottingham, England, sounded the alarm after an otherwise fit and healthy man in his 50s had a stroke and was left with permanent numbness in his hands and feet. On questioning, he said he drank an average of eight energy drinks a day.

The case, reported in the medical journal BMJ Case Reports, also prompted doctors to call for tighter regulation of sales and advertising of energy drinks.