Licorice (also spelled liquorice) is a spice made from the dried root of a shrub from the legume family.
The most commonly used licorice is often referred to as Spanish or Italian licorice (Glycyrrhiza glabra), which is native to Asia and the Mediterranean region.
Throughout the ages, it has been used in traditional herbal medicine in Asia and Europe.
Licorice is widely used as a flavoring in sweets, licorice sticks, chewing gum, chewing tobacco, cough mixtures, toothpaste, and beverages, such as soft drinks and beer.
It is also consumed as an ingredient in licorice tea and mixed herbal teas.
One of the main constituents of licorice, glycyrrhizin, is also very sweet, reputed to be much sweeter than regular table sugar.
Along with other bioactive substances found in licorice, glycyrrhizin has unique health effects, both good and bad.
This is what licorice root (on the left) looks like:
Dried licorice root is primarily composed of carbohydrates, minerals, and bioactive plant compounds.
By dry weight, the carbohydrates are mainly in the form of starch (30%), while the rest is made up of sugars, such as glucose, fructose, and sucrose (1).
Licorice root contains both insoluble and soluble fibers. Licorice extract only contains soluble fibers, which may have mild laxative effects when eaten in high amounts.
Licorice extract is commonly used as a flavoring in licorice confectionery (candy, sweets), which is especially popular in Northern Europe.
In fact, candy is one of the main dietary sources of licorice.
It is only found in so-called black licorice. Other types of confectionery that have a similar texture are sometimes referred to as licorice as well.
Like other confectionery, licorice candy has lots of added sugar, which may have adverse health effects when consumed in large amounts.
Commonly added ingredients include molasses, anise oil, ammonium chloride (in salty licorice), and a binder, such as starch, gelatin, or gum arabic.
Salty licorice, containing high amounts of ammonium chloride (salmiak), is very popular in Northern Europe.
Bottom Line: Licorice is often consumed as candy, which tends to be high in added sugar.
Other Plant Compounds
Licorice contains numerous bioactive substances, including polyphenol antioxidants and saponins.
Here are the main ones:
- Glycyrrhizin: Also called glycyrrhizic acid, glycyrrhizin is the most abundant plant compound in licorice root (2-3%) and extracts (10-25%). It is responsible for many of the health effects (1, 2, 3).
- Liquiritin: An antioxidant that contributes to the yellow color of licorice root (2).
- Liquiritigenin: One of the main antioxidants found in licorice. It is a phytoestrogen, a substance that resembles the female sex hormone, estrogen. It has a variety of health effects (4).
- Glabridin: An antioxidant and phytoestrogen that may have a number of health effects (5, 6).
Bottom Line: Licorice contains a number of bioactive plant compounds that are responsible for its health effects. These include glycyrrhizin, liquiritin, liquiritigenin, and glabridin.
Health Benefits of Licorice
Licorice has a long history of use in traditional herbal medicine. It has been used to treat many ailments (7).
Being rich in bioactive plant compounds, it can affect the body in numerous ways.
Prevention of Peptic Ulcers
Peptic ulcers, also known as gastric or stomach ulcers, are characterized by sores in the lining of the stomach.
The main symptoms include abdominal pain, nausea, and loss of appetite.
In worst case scenarios, the stomach wall may become perforated (punctured), a serious condition that requires immediate medical attention.
Infection by the bacterium Helicobacter pylori is one of the most common causes.
Throughout the ages, licorice root extracts have been used in the treatment of peptic ulcers (7).
Glycyrrhizin, one of the main bioactive compounds in licorice, is thought to be responsible for these protective effects.
Nevertheless, there is convincing evidence that licorice may, at least in some cases, provide benefits.
The anti-bacterial effects of licorice may be responsible for these effects. Glabridin, one of the compounds in licorice, can inhibit the growth of Helicobacter pylori, one of the main causes of peptic ulcers (12).
Bottom Line: Licorice may be beneficial in the treatment of peptic ulcers.
Obesity is a serious condition, characterized by excessive accumulation of body fat.
Similar effects have been seen in humans.
A randomized, controlled trial in 84 slightly overweight men and women found that taking 300-900 mg of licorice flavonoid oil every day for 8 weeks reduced body fat significantly compared with placebo (16).
Another small trial in 15 healthy men and women found similar results. Eating 3.5 grams of licorice extract per day for 2 months reduced body fat significantly. However, this study failed to include a control group (17).
These effects seem to be caused by glycyrrhizin, but the mechanism is unclear.
In short, the evidence indicates that eating licorice (or licorice flavonoid oil) may help in the prevention and treatment of obesity.
Keep in mind that this does not apply to licorice candy, which is loaded with added sugar.
Bottom Line: Licorice extract or licorice flavonoid oil may promote weight loss.
Adverse Effects and Individual Concerns
Eating high amounts of licorice may have serious side effects, such as high blood pressure, low levels of potassium, edema (swelling), and headache.
However, there is considerable individual variation in sensitivity to licorice.
Some people require only small doses, whereas others need to consume larger amounts to experience adverse effects.
In the majority of people, small amounts are unlikely to cause harm.
Elevated Blood Pressure
Hypertension is an adverse condition characterized by abnormally high blood pressure, increasing the risk of heart disease and strokes.
It is one of the most well-known side effects of licorice consumption.
Glycyrrhizin, the main bioactive compound, is believed to be responsible (18).
A study in 30 healthy men and women showed that eating 100 grams of licorice every day for 4 weeks resulted in a significant increase in blood pressure (19).
Even as little as 50 grams of licorice per day for 2 weeks may raise blood pressure in some individuals (20).
The effect is dose-related and highly variable between individuals. In some people, blood pressure may increase after eating only small amounts, whereas higher amounts are needed for others.
Bottom Line: Elevated blood pressure is a common side effect of licorice consumption in some people.
Loss of Potassium
Hypokalemia, a condition characterized by low levels of potassium in the blood, is a common side effect of excessive licorice consumption.
Like the elevation in blood pressure, it is caused by glycyrrhizin (21).
The main symptoms of severe hypokalemia include muscle weakness, abnormal heart rhythm, and muscle cramps. It is also a risk factor for heart disease (22).
The effect is reversible, and potassium levels return to normal a few weeks after consumption has stopped.
Bottom Line: Over time, excessive licorice consumption may lead to reduced levels of potassium in the blood, causing muscle weakness and muscle cramps.
Birth that occurs less than 37 weeks after the start of pregnancy is defined as premature birth (preterm delivery).
Babies that are born prematurely are at greater risk for various adverse health conditions, and may have delays in development.
Further studies are needed to confirm these findings.
Although the evidence is limited, pregnant women should limit their consumption of licorice.
Bottom Line: During pregnancy, high licorice consumption may cause premature birth, but the evidence is limited.
Many licorice products, such as candy, are loaded with added sugar.
Regular consumption of high-sugar foods may raise the risk of numerous health problems, such as obesity, diabetes, and heart disease.
For this reason, consumption of licorice candy should be limited.
Bottom Line: Licorice candy is usually very high in added sugar. In excess, it may promote weight gain, diabetes, and heart disease.
Licorice is a spice that is often used as a flavoring in candy.
It is rich in many unique plant compounds with a variety of health effects.
On the positive side, it may help prevent stomach ulcers and weight gain, but it also has a number of adverse effects, including elevated blood pressure.
For this reason, excessive consumption should be avoided.