Black licorice has a strong flavor that people tend to either love or avoid.
It is often eaten as a traditional candy, but consuming a large amount regularly can cause surprisingly serious health problems.
The concern comes from the U.S. Food and Drug Administration, which has warned that eating too much black licorice can affect the heart. Adults over 40 and people with certain health conditions may be particularly vulnerable.
Real licorice comes from the root of the Glycyrrhiza glabra plant, which grows in parts of Europe and Asia. Licorice root has a long history in traditional medicine and has been used for problems ranging from coughs and sore throats to digestive complaints.
But something being natural does not automatically make it safe in unlimited amounts. Real black licorice contains a naturally occurring substance called glycyrrhizin, which gives the root much of its characteristic sweetness.
When a person consumes a large amount of glycyrrhizin, it can disturb the body’s balance of important minerals. In particular, it can cause potassium levels in the blood to fall.
Potassium is essential for normal health. It helps nerves send signals, allows muscles to work and plays an important role in keeping the heart beating in a steady rhythm.
When potassium falls too low, a person may develop muscle weakness, tiredness or abnormal heart rhythms. Glycyrrhizin can also contribute to higher blood pressure and fluid retention, which may cause swelling.
In severe cases, these changes can become dangerous for the heart. People who already have heart disease, high blood pressure or other medical conditions may have less ability to tolerate these effects.
The FDA has warned that for people aged 40 or older, eating about two ounces of black licorice every day for at least two weeks could lead to an irregular heartbeat or other serious problems. Two ounces is roughly 57 grams, an amount that a regular candy eater could consume without realizing it might be risky.
The effect occurs because glycyrrhizin changes the way certain hormones work in the body. This can cause the kidneys to hold on to more sodium and water while the body loses potassium.
Age is not the only factor that matters. Some medicines can also affect potassium levels, blood pressure or heart rhythm, so eating large amounts of real licorice while taking certain medications may increase the chance of problems.
Possible interactions are particularly important for people taking medicines for heart conditions, high blood pressure or fluid buildup. Some supplements and herbal products can also contain licorice root or concentrated licorice extracts.
Consumers should also know that not every candy sold as licorice contains real licorice root. Some products use other flavorings, so the ingredient list can help show whether glycyrrhizin-containing licorice is actually present.
For most people, an occasional small serving is unlikely to cause the same problems as eating large quantities day after day. The main concern is repeated or heavy consumption, especially among people with additional health risks.
The effects are often reversible after a person stops consuming licorice, and potassium levels can return toward normal. However, a dangerous heart rhythm should never be treated as something to simply wait out at home.
Anyone who develops an irregular heartbeat, severe weakness, fainting or other concerning symptoms after eating a large amount of black licorice should stop eating it and seek medical advice. Severe symptoms, particularly fainting, chest pain or major breathing difficulty, require urgent medical attention.
The FDA’s safety information on black licorice is a public health warning rather than the publication of a new clinical research study. It is based on known effects of glycyrrhizin and reports of health problems associated with excessive licorice consumption.
The warning offers a broader lesson about foods and herbal products. A substance can have a long history of use and still cause harmful effects when the dose becomes high enough.
Black licorice does not need to disappear from the candy cupboard for most healthy people. The safer approach is simply to enjoy it in modest amounts, avoid eating large quantities continuously and pay attention to real licorice in candies, herbal products and supplements.
People with heart disease, high blood pressure or medicines that may interact with licorice should be especially cautious and can ask a doctor or pharmacist about their individual risk. A favorite sweet can still be enjoyed, but in the case of real black licorice, more is definitely not always better.
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