Beard lichen

Beard lichen (Usnea barbata), also known as Usnea, is a species of lichen that is widespread mainly in cool and temperate regions of the Northern Hemisphere. It usually grows on trees and is easy to recognize by its beard-like, thread-like appearance. Beard lichens have been known for their medicinal properties for centuries and were traditionally used in naturopathy.

What benefits does Beard lichen offer?

In folk medicine, Beard lichen has been used since time immemorial. It is applied there for various purposes but is used above all for:

  • Respiratory conditions: to treat coughs, bronchitis, and sore throats.
  • Skin infections: as an external remedy for wound healing and for treating fungal infections.
  • Infections of the digestive tract: against stomach pain and intestinal disorders.

The supposedly anti-inflammatory (1,2) and antimicrobial properties (1,3) of Beard lichen were traditionally valued, especially in European and Asian healing traditions.

Active compounds and modern research

The healing properties of Beard lichen are based on its bioactive constituents, in particular:

  • Usnic acid: In studies, usnic acid exhibited a whole range of different effects, including antimicrobial, antiviral, and anti-inflammatory properties (1,2,3). Some papers even link it to an antitumoral effect (3,4,5).
  • Polysaccharides: according to studies, influence the immune system and general health (6,7).
  • Phenolic compounds: Possessed antioxidant properties in studies(8).

Many studies have already been conducted on the various constituents of Beard lichen, but here too, in many areas further research is needed before one can speak of an actual body of facts. As in every other case, the validity of the studies must also be taken into account, and whether they have delivered readily transferable results

Applications

Beard lichen is used in folk medicine in various forms, including:

  • Teas and infusions: for respiratory conditions and for internal cleansing.
  • Extracts and tinctures: for use with infections and to strengthen the immune system.
  • Ointments and creams: for wound healing and treating skin infections.

Risks and side effects

Beard lichen is generally considered safe, but the following side effects can occur:

  • Allergic reactions in sensitive individuals.
  • Skin irritation with external use in high concentrations.
  • With long-term intake of high doses, liver problems can occur, as usnic acid is potentially hepatotoxic (1,9,10).

Pregnant women, breastfeeding women, and people with liver disease should refrain from using it.

Conclusion

Beard lichen is a versatile medicinal plant with a long tradition in natural medicine. Its antimicrobial and healing-promoting properties make it a valuable addition in the treatment of certain infections and skin conditions. Nevertheless, users should ensure responsible dosing and consult a doctor before taking it.

Sources:

  1. Chen, S., Ren, Z., & Guo, L. (2024). Hepatotoxicity of usnic acid and underlying mechanisms. Journal of environmental science and health. Part C, Toxicology and carcinogenesis, 1–22. Advance online publication. https://doi.org/10.1080/26896583.2024.2366737
  2. Paździora, W., Podolak, I., Grudzińska, M., Paśko, P., Grabowska, K., & Galanty, A. (2023). Critical Assessment of the Anti-Inflammatory Potential of Usnic Acid and Its Derivatives—A Review. Life, 13(4), 1046. https://doi.org/10.3390/life13041046
  3. Wang, H., Xuan, M., Huang, C., & Wang, C. (2022). Advances in Research on Bioactivity, Toxicity, Metabolism, and Pharmacokinetics of Usnic Acid In Vitro and In Vivo. Molecules, 27(21), 7469. https://doi.org/10.3390/molecules27217469
  4. Ingelfinger, R.; Henke, M.; Roser, L.; Ulshofer, T.; Calchera, A.; Singh, G.; Parnham, M.J.; Geisslinger, G.; Furst, R.; Schmitt, I.; et al. Unraveling the pharmacological potential of lichen extracts in the context of cancer and inflammation with a broad screening approach. Front. Pharmacol. 2020, 11, 1322.
  5. Eryilmaz, I.E.; Guney, E.G.; Egeli, U.; Yurdacan, B.; Cecener, G.; Tunca, B. In vitro cytotoxic and antiproliferative effects of usnic acid on hormone-dependent breast and prostate cancer cells. J. Biochem. Mol. Toxicol. 2018, 32, e22208.
  6. Murphy EJ, Fehrenbach GW, Abidin IZ, Buckley C, Montgomery T, Pogue R, Murray P, Major I, Rezoagli E. Polysaccharides-Naturally Occurring Immune Modulators. Polymers (Basel). 2023 May 19;15(10):2373. doi: 10.3390/polym15102373. PMID: 37242947; PMCID: PMC10222865.
  7. Shen, Y., Zhao, H., Wang, X., Wu, S., Wang, Y., Wang, C., Zhang, Y., & Zhao, H. (2024). Unraveling the web of defense: the crucial role of polysaccharides in immunity. Frontiers in immunology, 15, 1406213. https://doi.org/10.3389/fimmu.2024.1406213
  8. Zeb A. (2020). Concept, mechanism, and applications of phenolic antioxidants in foods. Journal of food biochemistry, 44(9), e13394. https://doi.org/10.1111/jfbc.13394
  9. Croce, N., Pitaro, M., Gallo, V., & Antonini, G. (2022). Toxicity of Usnic Acid: A Narrative Review. Journal of toxicology, 2022, 8244340. https://doi.org/10.1155/2022/8244340
  10. Guo L, Shi Q, Fang JL, Mei N, Ali AA, Lewis SM, Leakey JE, Frankos VH. Review of usnic acid and Usnea barbata toxicity. J Environ Sci Health C Environ Carcinog Ecotoxicol Rev. 2008 Oct-Dec;26(4):317-38. doi: 10.1080/10590500802533392. PMID: 19034791; PMCID: PMC5739313.