True black licorice, derived from the root of the Glycyrrhiza glabra plant, has a history of use as a flavoring agent and in traditional medicine. The distinctive sweet taste comes from a compound that can influence digestive function, leading many to question its potential for causing gastrointestinal upset. While many modern candies use anise oil for a similar flavor, true licorice root extract contains an active component that affects the digestive system.
The Direct Link: Licorice and Gastrointestinal Distress
Excessive consumption of products containing genuine licorice root extract can lead to diarrhea and general digestive discomfort. This effect stems from licorice’s mild laxative properties, sometimes utilized in traditional remedies to address constipation. When consumed in large amounts, the compounds in the licorice root can irritate the intestinal lining and increase the rate at which contents move through the digestive tract.
The resulting loose stools or diarrhea are a consequence of the body attempting to rebalance fluids in the gut. Licorice consumption disrupts the body’s electrolyte balance, which influences how water is retained or secreted within the intestines. This fluid imbalance manifests as an unwanted laxative effect, especially for those consuming highly concentrated extracts.
The Chemical Trigger: Glycyrrhizin and Its Function
The primary chemical responsible for the effects of licorice is glycyrrhizin, also known as glycyrrhizic acid. This compound, found naturally in the root, is metabolized in the gut to glycyrrhetinic acid, which directly interferes with a crucial enzyme in the body.
Specifically, glycyrrhetinic acid inhibits the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2). This enzyme normally inactivates the stress hormone cortisol in tissues like the kidney. By inhibiting 11β-HSD2, licorice prevents cortisol from being broken down, leading to elevated concentrations of active cortisol.
High levels of active cortisol inappropriately bind to and activate mineralocorticoid receptors in the kidneys, mimicking the effect of aldosterone. This phenomenon is known as pseudo-aldosteronism. The receptor activation triggers the kidneys to retain sodium and water while simultaneously excreting potassium. This shift in electrolytes causes the digestive tract to pull in excess water, contributing directly to diarrhea.
Defining “Too Much”: Safe Consumption Guidelines
The risk of adverse effects, including diarrhea, is directly related to the amount of glycyrrhizin consumed. Establishing a safe limit is complicated because the concentration of glycyrrhizin varies significantly between raw licorice root, concentrated extracts, and commercial candies. Regulatory bodies have provided guidance based on the active compound.
The Joint Food and Agricultural Organization/World Health Organization Expert Committee on Food Additives suggests that adult consumption of up to 100 milligrams of glycyrrhizic acid per day is unlikely to cause adverse health effects. For context, this 100 mg limit is roughly equivalent to consuming between 50 and 70 grams of typical black licorice confectionery.
Consuming this amount occasionally is different from chronic daily intake. Regular, high-dose consumption is most likely to lead to a buildup of glycyrrhetinic acid and subsequent health issues. Individuals should check product labels, especially for concentrated extracts or supplements, to determine the exact glycyrrhizin content and avoid prolonged daily use.
Non-Digestive Health Risks of Excessive Licorice
The same mechanism that disrupts fluid balance in the gut also leads to serious systemic health risks. The sodium and water retention caused by the pseudo-aldosteronism effect can result in hypertension, or high blood pressure. This is a concern, especially for individuals who already have underlying cardiovascular conditions.
The excessive excretion of potassium triggered by this mechanism can cause hypokalemia, an abnormally low level of potassium in the blood. Hypokalemia can manifest as muscle weakness, fatigue, and in severe cases, dangerous heart rhythm abnormalities. These systemic effects are almost exclusively seen with chronic, high-dose consumption and are typically reversible once licorice intake is stopped.