The Dual Nature of Licorice for Eye Health
Licorice root, derived from the plant Glycyrrhiza glabra, is known for its anti-inflammatory and antioxidant properties, primarily attributed to compounds like glycyrrhizin, glabridin, and isoliquiritigenin. While its topical use in controlled, clinical settings has demonstrated potential benefits for specific eye conditions, the consumption of excessive amounts of licorice candy or supplements is linked to serious health risks, including ocular complications. The key difference lies in the method of administration and dosage, with a stark contrast between targeted, medicinal use and casual, high-volume ingestion.
Potential Benefits of Topical Licorice and Its Derivatives
Research has explored the use of licorice derivatives in ophthalmic preparations for treating certain eye ailments, with promising results in controlled studies.
- Dry Eye Disease (DED): A 2018 pilot study found that eye drops containing 2.5% glycyrrhizin were well-tolerated and provided significant clinical benefits for patients with moderate DED. The compound binds to the pro-inflammatory protein HMGB1, inhibiting cytokine activity and reducing inflammation on the ocular surface.
- Keratitis and Conjunctivitis: In traditional Chinese medicine and some studies, licorice extracts have been used topically to treat inflammatory eye conditions like keratitis and conjunctivitis. Glycyrrhizin has shown both anti-inflammatory and antimicrobial properties against certain bacteria causing keratitis.
- Anti-angiogenic Properties: Flavonoids from licorice, such as isoliquiritigenin (ISL), have demonstrated anti-angiogenic activity, suppressing the growth of new blood vessels in the retina. This is particularly relevant for conditions like wet age-related macular degeneration (AMD) and corneal neovascularization, though further research is needed.
- Under-eye Skin Care: Some cosmetic formulations use licorice root extract for the skin around the eyes. The extract is rich in glabridin, which helps soothe inflammation and inhibit melanin production, potentially reducing the appearance of dark circles and hyperpigmentation.
Significant Risks of Excessive Oral Licorice Intake
In contrast to the targeted topical use, consuming large quantities of licorice candy or root orally is dangerous and can lead to severe health issues, some of which directly affect vision.
- Transient Vision Loss: Excessive oral intake of licorice has been linked to episodes of transient visual loss, a condition known as transient monocular or binocular vision loss. This is believed to be caused by vasoconstriction, or the narrowing of blood vessels, in the retina or occipital region.
- Hypertension and Cardiac Issues: The active compound glycyrrhizin can cause high blood pressure by affecting aldosterone, a hormone that regulates salt and water balance. This can put stress on the entire vascular system, including the delicate blood vessels in the eyes, which could be related to the vision loss episodes.
- Other Systemic Side Effects: High licorice consumption can also lead to other serious health problems, such as: hypokalemia (low potassium levels) which can cause muscle weakness and irregular heart rhythms; and hormonal imbalances. These systemic issues can indirectly impact overall health, including vision.
The Importance of Form and Quantity
| Feature | Topical Licorice (e.g., Eye Drops) | Oral Licorice (e.g., Candy, Tea) |
|---|---|---|
| Application | Direct to the eye's surface, controlled concentration | Ingested into the digestive system, systemic effect |
| Active Compounds | Isolated, specific compounds like glycyrrhizin | Full-spectrum root extract, variable concentrations |
| Dose | Low, therapeutic concentrations, carefully measured | Often high and unregulated, especially in candy |
| Effect | Anti-inflammatory, antimicrobial, anti-angiogenic | Potential for systemic toxicity, hormonal effects |
| Primary Benefits | Alleviating dry eye symptoms, treating keratitis | Traditional use, but significant risks for eye health |
| Primary Risks | Very low; occasional, transient irritation | Hypertension, vision loss (vasospasm), hypokalemia |
Understanding Different Licorice Products
Not all licorice products are created equal. Some licorice-flavored candies use anise oil for flavor and contain no actual licorice root or its active compounds, making them a non-factor for eye health. For those seeking potential health benefits, deglycyrrhizinated licorice (DGL) is an option, where the problematic glycyrrhizin is removed. However, the eye-related benefits are primarily linked to glycyrrhizin, so DGL is not relevant for those specific applications. Ultimately, any medicinal use of licorice, particularly for the eyes, should be discussed with a healthcare professional to ensure safety and effectiveness. The National Center for Complementary and Integrative Health (NCCIH) notes that high-quality evidence is still lacking to clearly support the use of licorice for many health conditions.
Conclusion
In summary, the question of whether licorice is good for your eyes has two distinct answers depending on the context. Used topically in controlled clinical studies, particularly in glycyrrhizin-based eye drops, it has shown promise in managing specific conditions like moderate dry eye disease and keratitis by reducing inflammation. However, the casual, excessive consumption of oral licorice, particularly in candy or unregulated supplements, carries significant risks, including potentially severe side effects like hypertension and temporary vision loss. For this reason, licorice for eye-related issues should only be considered under strict medical supervision and is not a safe self-prescribed remedy. High-quality scientific evidence supporting widespread use remains limited, emphasizing the need for caution and professional guidance.
For more information on the active compounds and their effects, you can visit the Angiogenesis Foundation website.
