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Licking the Liquorice Habit

A twenty-year old woman showed up in the emergency room because she had lost all strength in the lower half of her body. Blood tests quickly revealed an extremely low potassium level. Why? Liquorice!

An astute physician immediately asked about the woman's dietary habits and discovered that she was virtually addicted to liquorice candies, eating up to half a pound a day! Right then and there the problem was solved. The most prevalent compound in liquorice, and the most studied, is glycyrrhizin, also known as glycyrrhizic acid. This has hormonal effects resembling those of aldosterone, an adrenal gland hormone that is responsible for maintaining mineral balance in the blood by helping the body retain sodium and excrete potassium. Too much aldosterone, or compounds that behave like it, will cause excessive sodium retention and excessive potassium loss (which, as an aside, can cause high blood pressure, but this is not what was diagnosed with this twenty-year old). This loss of potassium can affect nerve and muscle function and in the case of our liquorice-guzzling patient, potassium supplementation quickly reversed the problem.

This case is not unique. A man who switched to a liquorice-flavoured beverage when he was told to give up alcohol also ended up in hospital with weakness, high blood pressure and low potassium. So did a man who had managed to give up smoking by switching to chewing gum flavoured with real liquorice. His severe abdominal pains turned out to be due to potassium loss. Here in North America, liquorice is commonly used to flavour tobacco. In fact, about 90% of the liquorice imported into North America is used for this purpose, making it no real surprise to hear of the man who chewed about ten 3-ounce bags of tobacco flavoured liquorice a day who then became so weak he couldn’t even raise his arms. And then there was one study where subjects were asked to eat approximately one to two hundred grams of liquorice candies daily, which resulted in some serious symptoms appearing within a few weeks. So the moral here is obvious. Do not consume unusual amounts of authentic liquorice (like these and these), especially if there is a history of high blood pressure or other medical problems like diabetes, heart disease or glaucoma.

Why would anyone consider eating exceptional amounts of liquorice anyway? There seem to be plenty of reasons when one consults the herbal or alternative literature. Often liquorice is touted as a “natural” treatment for conditions ranging from colds and prostate problems to indigestion and cancer. In most cases, the results of animal experiments are blown out of proportion and human experiences are exaggerated. For example, just because mice exposed to a carcinogen developed fewer tumours when they drank water laced with glycyrrhizin does not mean that liquorice is an effective treatment for human cancer. Or just because there is some evidence that liquorice can help heal peptic ulcers in humans does not mean it is the best therapy. At one time, it may have been an appropriate treatment until newer, far more effective prescription drugs came on the scene, but these days there is no reason for liquorice to be used as a treatment.

Liqourice is one of the most widely investigated plant products. Modern chemistry has allowed for the isolation, separation, and characterization of dozens of different compounds found in the root extract. No single component accounts for the characteristic flavour, but anethole comes close. The anethole compound is also found in the anise plant, from which it can be extracted, or it can be synthesized in the laboratory. Anethole is commonly used to impart the liquorice flavour to candies, as in the case of the familiar black stringy variety. That’s why characterizing these types of candies as "liquorice" is misleading, since even when it is made with real liquorice extract, the actual concentration of liquorice compounds is very low. This is important to know because it means that the problems attributed to real liquorice do not apply to the twists we chew on in movie theatres. Thank goodness!

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