Licorice is mostly known for its flavor and association with candy. However, this plant root has long been used as a traditional medicine. Now, researchers are finding that the compounds in licorice may help fight certain infections. Can it help fight the current coronavirus outbreak as well?
This article is for informational purposes only. The current coronavirus outbreak is an ongoing event and certain details may change as new information comes to light. Overall, the best preventive measures you can take against COVID-19 are basic standard precautions, including social distancing, hand washing, and avoiding touching your face.
Does Licorice Have a Role in the COVID-19 Pandemic?
Licorice, or liquorice, refers to the root of the Glycyrrhiza glabra plant which is often used for its sweet flavor.
This plant root is also used in many traditional herbal medicines, where it is believed to help with digestive issues, cough, menopausal symptoms, and infections [1].
According to research, there may be some validity to these claims as researchers have found that the active compounds inside licorice may have antiviral properties [2].
Make no mistake, there is no evidence that licorice can help prevent or treat the ongoing outbreak of COVID-19.
However, studies do show that licorice may have antiviral activity against viruses that are closely related to the new coronavirus, which makes it an interesting candidate for future research [2].
This article will focus on the link between licorice and the immune system. Check out this article for a more comprehensive look at licorice.
How Does Licorice Help the Immune System?
One of the main active compounds inside licorice is glycyrrhizin, which has a variety of effects in the body, including antiviral properties [2].
According to research, glycyrrhizin may help fight infections through several mechanisms, including [2]:
- Interfering with the ability of viruses to release from infected cells
- Inhibiting virus gene expression
- Activating the development of T-cells
Licorice contains many other biologically active compounds that may also have antimicrobial properties, such as licochalcone A, liquiritigenin, and glabridin [2].
Glycyrrhizin Toxicity
While glycyrrhizin is responsible for many of the antiviral effects of licorice, this compound is also associated with several side effects and safety concerns.
Consuming large amounts of licorice or long term use can cause high blood pressure and low potassium levels, which can result in heart and muscle issues [1].
There’s also some evidence that consuming licorice root during pregnancy may lead to developmental issues in children [1].
There are licorice products called ‘deglycyrrhizinated licorice’ that have had their glycyrrhizin content removed. This may reduce side effects, but also may decrease antiviral activity [3].
Licorice For Infections
The use of licorice for the new coronavirus outbreak has not been studied, but previous studies have looked at its effects on closely related viruses [4].
One such virus is SARS-CoV-1, another type of coronavirus, which was responsible for the SARS outbreak in 2002-2003.
A study found that glycyrrhizin was able to block the replication of SARS-CoV-1 samples that were isolated from patients with SARS [4].
However, it’s important to note this result was only observed in isolated test-tube experiments. It’s impossible to say if licorice would have the same effects in the actual human body [4].
Other Types of Infections
A small randomized clinical trial of 28 patients compared the effects of maoto (an herbal product that contains licorice root) with oseltamivir and zanamivir, two drugs commonly used to treat and prevent influenza (the flu) [5].
Researchers found that the maoto herbal product was just as effective as oseltamivir and zanamivir for treating flu symptoms and reducing viral activity [5].
In contrast, another study of 70 patients with respiratory tract infections showed that a different herbal product containing licorice called Kikyo-to was not effective at relieving sore throat symptoms [6].
A number of clinical trials also suggest that an injectable form of glycyrrhizin may reduce markers for liver damage in patients with hepatitis C and B [7, 8, 9].
According to research in animals and cells, licorice root may have antiviral activity against many additional types of viruses, such as:
- Porcine reproductive and respiratory syndrome virus (PRRSV) [10]
- Viruses that cause Hand-foot-and-mouth disease [11]
- Human respiratory syncytial virus (HRSV) [12]
- Rotavirus [13, 14]
- Influenza virus A2 (H2N2) [15]
- Influenza A (H3N2) [16]
It’s important to note that human studies are limited and often use combination herbal products or injectable formulations, which makes it difficult to apply these findings to supplemental forms of licorice.
Licorice For Lung Function
Beyond its potential antiviral effects, licorice root may also have beneficial effects on lung health.
For example, a study of 46 children with respiratory tract infections found that an herbal mixture containing licorice root may be able to reduce coughing and awakenings during the night [17].
According to another study of 70 patients with a chronic cough, licorice pastille (a type of candy) was able to significantly reduce coughing compared to placebo [18].
Animal studies show that licorice may also protect against lung injury and reduce airway inflammation in asthmatic mice [19, 20, 21].
Dosage
Talk to your doctor before taking licorice. There may be serious interactions with your current medications or health conditions. Long-term use and consumption of large amounts of licorice can result in serious side effects.
A large majority of clinical trials on licorice have studied it as a component of various herbal mixture products, making it difficult to identify an ideal dose.
For those that do decide to take licorice, it is important to limit your intake of glycyrrhizin. According to some studies, daily glycyrrhizin intake should not exceed 0.2 mg/kg of body weight [22, 23].
Takeaway
The licorice root is often utilized for its sweet flavor, but it may also have several health benefits.
There is some evidence that licorice may help fight certain infections, including viruses that are closely related to the current coronavirus outbreak.
However, research in humans is limited and often involves products that contain several different herbal ingredients in addition to licorice, making it difficult to evaluate its true effect.
For now, the best preventive measures you can take against COVID-19 are standard precautions, including social distancing, hand washing, and avoiding touching your face.
