The Traditional Use and Mild Laxative Effect of Licorice
Licorice root (Glycyrrhiza glabra) has a rich history in both Western and Eastern herbal medicine, where it was historically used for a variety of ailments, including as a mild laxative. Traditional Chinese Medicine (TCM) texts, such as the "Treatise on Febrile Diseases," mention its use in formulas to treat constipation. The presumed benefit is often attributed to its ability to soothe the gastrointestinal mucosa and promote mild laxative effects. However, it is important to distinguish between traditional folk usage and scientifically validated therapeutic approaches. While anecdotal evidence and centuries of use suggest a benefit, modern science offers a more nuanced view.
The Role of Glycyrrhizin
The primary active compound responsible for licorice's characteristic sweet flavor and many of its physiological effects is glycyrrhizin. When ingested, glycyrrhizin has poor oral bioavailability and is primarily hydrolyzed by intestinal bacteria into a more readily absorbed metabolite, glycyrrhetic acid. This process is key to understanding its effects. Glycyrrhetic acid is then responsible for many of the medicinal and adverse effects associated with licorice consumption.
How Glycyrrhizin Influences Intestinal Function
Recent animal studies have started to uncover the complex mechanisms by which licorice extract, and by extension glycyrrhizin, can influence the digestive system.
- Modulation of Neurotransmitters: Licorice water extract (LWE) has been shown to increase levels of excitatory neurotransmitters (like 5-hydroxytryptamine and motilin) that stimulate intestinal movement. Simultaneously, it can decrease levels of inhibitory neurotransmitters (like vasoactive intestinal peptide and nitric oxide) that slow down gut motility.
- Intestinal Water Transport: Glycyrrhizin may increase the expression of water channel proteins (aquaporin 3) in the colon, which boosts water transport into the fecal matter. This helps to soften stool and ease its passage.
- Intestinal Barrier Repair: Animal research indicates that LWE can help repair a damaged intestinal barrier, which is often compromised in cases of constipation. This involves upregulating certain gene expressions that are crucial for maintaining the gut lining.
- Gut Microbiota Regulation: Licorice extract can also be metabolized by gut bacteria, which in turn can restore dysbiosis associated with constipation.
Significant Risks and Adverse Effects of Licorice
Despite its potential benefits, licorice consumption—particularly in high doses or over a long duration—carries considerable health risks, primarily due to the glycyrrhizin content. The most significant adverse effect is a condition known as pseudoaldosteronism.
Pseudoaldosteronism Effects:
- Hypertension (High Blood Pressure): Glycyrrhizic acid inhibits the enzyme that inactivates cortisol. This leads to an increase in cortisol, which then mimics the action of aldosterone, causing sodium retention and potassium excretion. The resulting fluid imbalance can increase blood pressure.
- Hypokalemia (Low Potassium): The excessive potassium excretion can lead to dangerously low potassium levels in the blood. This can manifest as muscle weakness, fatigue, arrhythmia (irregular heartbeats), and in severe cases, paralysis. Hypokalemia can even, paradoxically, cause or worsen constipation.
- Edema (Swelling): The sodium and water retention can cause significant swelling in the body, particularly in the ankles and feet.
Because of these risks, the FDA cautions individuals over 40 to avoid consuming more than two ounces of black licorice daily for over two weeks. The European Union has also suggested a provisional upper limit for daily glycyrrhizin intake.
Deglycyrrhizinated Licorice (DGL)
For those interested in licorice's digestive benefits without the risk of hormonal side effects, Deglycyrrhizinated Licorice (DGL) is available. In DGL supplements, the glycyrrhizin compound is removed, making it a safer option for treating certain digestive issues like heartburn and ulcers. However, DGL does not possess the same laxative properties, as the key active ingredient for that effect is missing.
Comparison of Laxatives: Licorice vs. Common Alternatives
It's important to understand how licorice stacks up against more established and safer options for managing constipation.
| Feature | Licorice (High Glycyrrhizin) | Prunes (Dried Plums) | Senna (Herbal Laxative) |
|---|---|---|---|
| Mechanism | Influences neurotransmitters, increases water transport, modulates microbiota; also has hormonal effects. | Provides dietary fiber and sorbitol, a natural sugar alcohol, which pulls water into the colon. | Contains sennosides, compounds that irritate the colon lining to stimulate strong contractions. |
| Potency | Mild to moderate effect, based on dosage and individual sensitivity. | Mild to moderate, considered a gentle option. | Strong, fast-acting stimulant laxative. |
| Primary Active Component | Glycyrrhizin (leading to glycyrrhetic acid). | Sorbitol and fiber. | Sennosides. |
| Key Side Effects | High blood pressure, hypokalemia, edema, and potentially irregular heartbeat. | Gas and bloating with high doses. | Abdominal cramping, dependency with long-term use. |
| Overall Safety | Risky for high or long-term use due to severe side effects. Not recommended as a primary laxative. | Generally safe and well-tolerated. Good for long-term dietary inclusion. | Effective for short-term use, but not for chronic constipation. |
Conclusion: Making an Informed Choice
While ancient texts and traditional uses suggest that licorice acts like a laxative, modern scientific evidence paints a more cautious picture. The mild laxative effect, mediated by the compound glycyrrhizin, is not robust enough to be a reliable primary treatment for constipation. Furthermore, the potential for serious and dangerous side effects, such as high blood pressure and low potassium, makes high or chronic licorice consumption a significant health risk.
For those seeking relief from occasional constipation, safer and better-studied natural alternatives like prunes are widely available and recommended. If you are considering using licorice or any herbal supplement for a digestive issue, it is crucial to consult a healthcare professional. They can help you weigh the potential benefits against the serious risks and guide you toward a safe and effective treatment plan. Relying on tradition alone when significant scientific concerns exist is not a prudent approach for your digestive health.
Can Licorice Candy Help with Constipation?
It is worth noting that most commercial licorice candy does not contain significant amounts of real licorice root extract. The candy is often flavored with anise or other artificial ingredients. Therefore, expecting licorice candy to have a medicinal effect, whether positive or negative, is generally unfounded. In fact, consuming too much candy can lead to a diet high in sugar and low in fiber, which may exacerbate constipation.
For more information on the safety of herbal supplements, consult authoritative sources like the National Center for Complementary and Integrative Health (NCCIH). [https://www.nccih.nih.gov/health/licorice-root]
