Beware Black Licorice

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With wrapped treats aplenty this Halloween, there's one candy to embrace in moderation.

The U.S. Food and Drug Administration warns that consuming too much black licorice could lead to heart arrhythmias, especially in the 40-and-over crowd.

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Here's why: A main ingredient in black licorice root, glycyrrhizin, can lower potassium levels in a person's body, which can have negative effects on the heart. The FDA sets limitations on how much glycyrrhizin can be used in food products, but people can still take in more of the ingredient through eating multiple servings.

Health officials say people 40 and older should avoid consuming more than 2 ounces of the treat for consecutive days. One case study suggests a patient experienced pulmonary edema, a side effect of heart failure, from binging on black licorice.

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For most healthy people, an irregular heartbeat usually doesn't cause health problems, but the condition can be harmful for some. Signs of a heart arrhythmia include a racing heartbeat, chest pain, shortness of breath and a slow heartbeat, among others, according to the Mayo Clinic.

Most cases are resolved after a patient quits eating the black candy. But for black licorice lovers of any age, be careful about eating too much of the stuff, recommends the FDA.

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If you're unsure about whether a given candy or food contains glycyrrhizin, check the nutrition label to see if terms such as "licorice extract" or "licorice root extract" are listed among the ingredients, says Hershey's, the manufacturer of popular licorice products in the United States such as Twizzlers and Good & Plenty.

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Licorice root may also be present in certain dietary supplements, too. But some products offer licorice with the glycyrrhizin removed. The government also discourages pregnant women from taking any amount of licorice because of the root's potential ability to affect the health of moms and babies. In one experiment, licorice consumption was linked to early birth in some women.