A construction worker in the US state of Massachusetts was killed by his liquorice habit, doctors say.

The man, who has not been named but was 54 years old, ate about one-and-a-half bags of black liquorice every day.

He had suffered no symptoms before suddenly going into cardiac arrest in a fast food restaurant.

Describing the man’s case in the New England Journal of Medicine, his doctors said the glycyrrhizic acid in liquorice was to blame.

“We are told that this patient has a poor diet and eats a lot of candy. Could his illness be related to candy consumption?” Dr Elazer R Edelman said.

He said studies had shown glycyrrhizic acid – the active ingredient in liquorice – could cause “hypertension, hypokalemia, metabolic alkalosis, fatal arrhythmias, and renal failure” – all of which were seen in this patient.

Hypokalemia is when a person’s potassium levels in their blood become dangerously low.

The patient had also recently changed the type of sweets he was eating. A few weeks before his death, he switched from red fruit-flavoured twists to another type made with black liquorice.

Another doctor, Dr Andrew L Lundquist, agreed in the report that the liquorice was to blame.

He wrote: “Further investigation revealed a recent change to a liquorice-containing candy as the likely cause of his hypokalemia.”