From a medical standpoint, few foods are more interesting than licorice. It has been used since ancient times as an herbal remedy for coughs, upset stomachs and other ailments. Hundreds of bioactive compounds in licorice have been identified.
The positive: Licorice was among the first foods to be examined by the National Cancer Institute’s Experimental Food Program. This and other research has found anti-cancer potential for licorice or its compounds, at least in the lab, as well as other possible benefits.
The negative: Real licorice, from the root of the Glycyrrhiza plant, contains glycyrrhizin, a compound that can, in susceptible people, affect the body’s sodium and water balance. Regularly consuming even moderate amounts (two to three ounces daily) can lead to low potassium levels, fluid retention, dangerously elevated blood pressure and heart problems. However, problems have also been reported with smaller portions. Large amounts can have hormonal effects, such as lowering testosterone in men.
But keep in mind: All this is true only of real licorice. Most licorice made in the U.S. (and all red licorice) is just sugar, flavoring (artificial or from aniseed oil), and other ingredients. European black licorice is likely to be the real thing—it will list “licorice extract” or “licorice root powder” as an ingredient, though the concentrations vary.
Bottom line: Licorice is candy and thus usually high in sugar and calories, so eat only small portions. You should especially limit your intake of real licorice, unless the package says that the glycyrrhizin has been removed. If you have high blood pressure or heart disease, are taking diuretics or the blood thinner warfarin, or are pregnant or breastfeeding, your best bet is to avoid real licorice. Ask your doctor or pharmacist if any other drugs you are taking may interact with licorice.
Licorice root also comes as an herbal supplement (usually chewable tablets), promoted to “relieve stomach discomfort” and other ailments. There’s little or no evidence to support such claims.