After a generally healthy 54-year-old man collapsed and died from a heart attack, doctors discovered an unlikely culprit—black licorice—led to his death, according to a case study recently published in the New England Journal of Medicine.

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'We had no other clear cause'

In January 2019, the man profiled in the case study, who was a construction worker living in Massachusetts, had consumed one to two large bags of black licorice every day for three weeks. Then, while eating lunch at a fast-food restaurant, he suddenly collapsed.

Emergency responders performed CPR on the man and revived him, but he died about 24 hours after he arrived at Massachusetts General Hospital (MGH).

Providers at MGH found that the man's potassium level was extremely low, which likely had caused issues with his heart rhythm and other problems. The man had a generally poor diet, and he smoked a pack of cigarettes a day, doctors said. However, according to Jacqueline Boykin Henson, an internal medicine resident physician who treated the man at MGH, he had no family history of cardiac disease or any other conditions that would have led to his dangerously low level of potassium.

Ultimately, the man's providers concluded that the drop in his potassium levels that lead to his cardiac arrest was caused by consuming a large amount of glycyrrhizic acid, which is contained in black licorice.

"We had no other clear cause for why his potassium levels were so low," Henson said. She explained, "While his diet consisted largely of black licorice, he was active and otherwise generally healthy," and suffering from no underlying conditions that would have impacted what happened to him."

Still, Henson said, the man's providers all were "shocked and surprised" by their findings.

A public health warning: 'Consuming large amounts of licorice can be hazardous to your health'

FDA on its website warns that eating as little as two ounces of black licorice daily for two weeks could lead to heart rhythm problems, especially among people older than 40. The agency notes that glycyrrhizin, a compound derived from the licorice root, can lead to dropping potassium levels, which can cause abnormal heart rhythms, high blood pressure, edema, lethargy, and congestive heart failure.

"Individuals who enjoy black licorice should be cognizant of these potential health effects and should be conscious of the amount they are eating and how often," Henson said. "If they experience any symptoms concerning for electrolyte abnormalities such as muscle weakness or abnormal heart rhythms, they should stop taking black licorice," and "[i]ndividuals who already have either of these problems should probably avoid consuming black licorice," she added.

Neel Butala, one of the authors of the case study and a fellow at the interventional cardiology unit at MGH, said the man's case "raises a public health issue that consuming large amounts of licorice can be hazardous to your health."

Butala added that candy and food manufacturers should inform consumers how much glycyrrhizic acid is contained in their products.

And Robert Eckel, a cardiologist at the University of Colorado and former president of the American Heart Association, said Americans should be aware of the amounts of glycyrrhizic acid that are present in other foods, too.

"It's more than licorice sticks. It could be jelly beans, licorice teas, a lot of things over the counter," Eckel said. "Even some beers, like Belgian beers, have this compound in it."

Keith Ferdinand, a cardiologist at Tulane University School of Medicine, who was not involved in the case, said while the case was "very unusual," it should be viewed as a warning to consumers "to be aware that any substance that's taken into the body, especially taken in excess, can have true physiological effects" (Marchione, Associated Press, 9/23; Cramer, New York Times, 9/26; Giuliani-Hoffman, CNN, 9/25).