"Black licorice can lead to heart arrhythmias and other health problems when consumed by adults in large quantities, the FDA noted in its pre-holiday alert.
Experts say that consuming 2 ounces of black licorice per day for two weeks can set the heart stuttering in susceptible individuals. The culprit is a compound called glycyrrhizin, which is what gives licorice its sweet flavor.
Glycyrrhizin causes the kidneys to excrete potassium. And low levels of potassium can make the heart beat dangerously fast or out of sync, says Dr. Gregg Fonarow, a professor of cardiovascular medicine at the University of California, Los Angeles, School of Medicine.
The compound also leads to salt and water retention which can be a problem for people with heart failure or high blood pressure, Fonarow said.
It’s long been known in some cultures that licorice was more than just a sweet indulgence. In certain parts of the world, the chewy stuff is prescribed to treat everything from heartburn to bronchitis to viral infections. So far, though, there hasn’t been a study proving that licorice can cure anything, the FDA alert noted.
Because licorice is a bioactive food, which means it can tweak metabolic processes in the body, you also have to worry about interactions with medications, Fonarow said."