Licorice, derived from the root of the Glycyrrhiza glabra plant, is a popular flavoring agent used in various candies, teas, and herbal supplements. While prized for its distinct sweet taste, licorice consumption is directly linked to a recognized health concern: the potential to elevate blood pressure. This effect is supported by a clear physiological mechanism that can cause a significant rise in blood pressure, particularly with chronic or high-dose intake. Individuals consuming products containing natural licorice root should be aware of this risk and understand the specific compounds responsible.
The Direct Connection: Licorice and Blood Pressure
The definitive link between licorice consumption and hypertension is tied to a naturally occurring compound called glycyrrhizin, also known as glycyrrhizic acid. This triterpenoid saponin is responsible for the intense sweetness of licorice root, often tasting 30 to 50 times sweeter than table sugar. The risk of blood pressure elevation exists only in products containing this compound, such as pure licorice candies, teas, and herbal extracts.
When ingested, glycyrrhizin is metabolized in the gut by bacteria, converting it into its active form, glycyrrhetinic acid. This metabolite directly interferes with the body’s systems regulating blood pressure and electrolyte balance. Products labeled as Deglycyrrhizinated Licorice (DGL) have had the glycyrrhizin removed, making them safe for consumption without the risk of causing hypertension.
The Biological Mechanism of Action
The elevation in blood pressure is initiated by glycyrrhetinic acid’s ability to inhibit a specific enzyme in the kidneys: 11-beta-hydroxysteroid dehydrogenase type 2 (11-\(\beta\)-HSD2). This enzyme’s normal function is to convert the stress hormone cortisol into its inactive form, cortisone, primarily within the renal tubules.
By blocking the 11-\(\beta\)-HSD2 enzyme, glycyrrhetinic acid prevents the inactivation of cortisol. This results in an abnormally high concentration of active cortisol acting on the mineralocorticoid receptors (MR) in the kidney. These receptors are designed to be activated by the hormone aldosterone, which regulates sodium and potassium balance.
Because cortisol and aldosterone share a similar molecular structure, the excess active cortisol effectively mimics the action of aldosterone, a condition termed pseudohyperaldosteronism. The overstimulated receptors signal the kidneys to increase the reabsorption of sodium and water. Concurrently, the kidneys increase the excretion of potassium into the urine, leading to electrolyte loss. The resulting increase in total fluid volume in the bloodstream, combined with the electrolyte imbalance, drives the rise in blood pressure.
Defining Safe Consumption Levels
Determining a universally safe daily intake of licorice is challenging because the glycyrrhizin content varies widely between products, from candies to teas to supplements. Major health organizations have established provisional limits for glycyrrhizin consumption. The World Health Organization (WHO) and the European Commission’s Scientific Committee on Food suggest that most healthy adults are unlikely to experience adverse effects consuming less than 100 milligrams (mg) of glycyrrhizin per day.
This 100 mg limit serves as a general guideline for chronic daily consumption, though some studies indicate that even lower doses can affect sensitive individuals. The Acceptable Daily Intake (ADI) is sometimes calculated as 0.2 mg per kilogram of body weight per day. Due to this variability, continuous, high-dose intake of any product containing natural licorice root should be avoided.
Individuals with pre-existing conditions should exercise heightened caution or avoid licorice altogether. Those with established hypertension, heart disease, kidney impairment, or a history of stroke are considered high-risk groups. Licorice can also interact with medications like diuretics and corticosteroids, intensifying their effects or side effects, requiring professional consultation before consumption.
Recognizing and Reversing Related Symptoms
The clinical consequences of licorice-induced blood pressure elevation, or pseudohyperaldosteronism, present with a distinct set of symptoms. The most obvious sign is a persistent elevation in blood pressure, often accompanied by noticeable fluid retention (edema), particularly in the lower extremities. The loss of potassium, known as hypokalemia, can lead to more serious physical symptoms.
Low potassium levels may manifest as muscle weakness, fatigue, and headaches. In severe cases, hypokalemia can disrupt the heart’s electrical rhythm, potentially causing cardiac arrhythmias. If these symptoms appear following regular licorice consumption, discontinue the product immediately and seek medical evaluation.
Fortunately, licorice-induced hypertension is typically reversible once the source of glycyrrhizin is removed from the diet. Blood pressure and potassium levels usually begin to normalize within a few days to a few weeks after stopping consumption. Full metabolic recovery is often achieved within two to three weeks, though the suppression of the body’s natural blood pressure regulation system may take longer to fully resolve.