This popular treat may have unintended consequences for your blood pressure. Here’s what the science says and how much is safe to enjoy.

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black licorice in a pile
Credit: Getty Images/Jose A. Bernat Bacete

The most controversial thing about black licorice used to be the flavor of the candy. But a recent report, published in the New England Journal of Medicine, found that a man in Massachusetts passed away from a heart arrhythmia last year, after consuming black licorice every day for weeks. While this case is sad—and rare—it may have left you wondering if it's safe to eat black licorice and how much is too much. We dove into the science to learn more. 

Black licorice has some of its flavors derived from licorice root. The plant is grown in parts of Europe, Asia and the Middle East and has a long history of being used for medical purposes. From digestive distress to kidney disease, many believe that licorice root has a range of health benefits. Beyond popular candies, licorice root is used in teas, lozenges and even topically in skin care products. 

There is a chemical in licorice root called glycyrrhizic acid. Glycyrrhizic acid provides the sweet flavor from the licorice plant, and may have some anti-inflammatory benefits. However, it also contains enzymes that influence how your body balances sodium and potassium. If eaten in excess, it can cause potassium levels to fall in your body, drastically increasing your blood pressure, which has serious consequences for your heart. Many licorice products intentionally remove this compound, to create deglycyrrhizinated (DGL) licorice which may not have the same degree of side effects. 

The FDA recommends that no one eats a lot of black licorice at once, regardless of age. For those over the age of 40, eating more than two ounces a day (about 6 pieces of licorice) for more than two weeks is enough to put you at risk for irregular heart beats. If you eat black licorice regularly and notice irregular heart beat or weakness, stop eating it and call your doctor immediately. It's also a good idea to let your doctor know if black licorice is something you eat, since it can interact with some medications and supplements.

The FDA also sets limits to how much glycyrrhizic acid is allowed in food products and drinks. For soft candies, like chewy licorice, the amount is capped at 3.1%. However, many kinds of licorice candies in the U.S. do not actually contain any licorice root at all. Anise oil has a similar smell and flavor, and is often used in its place.

If you love black licorice and eat it regularly, try to choose products with DGL licorice or those that use anise oil instead for a flavorful, safe treat. Otherwise, be mindful about portion size and frequency when eating black licorice.