Wise Mind Herbs

The information on this page has been prepared with reference to published scientific literature, not by a medically qualified expert. It is not medical advice. Any decision to use a supplement or herb-based product is your responsibility. Consult a suitably qualified medical professional, especially if you have underlying conditions. Remember, nothing is for everyone, and not everything sold is what it claims to be. Some things work for some people, some of the time.

Icelandic Moss - Cetraria islandica

Icelandic moss (Cetraria islandica) is a lichen species that has been traditionally used in folk medicine across Northern European countries. Despite its common name "moss," it is actually a symbiotic relationship between a fungus and an alga. Other common names include Iceland lichen, Iceland cetraria, and eryngo-leaved liverwort. It should not be confused with Irish moss (Chondrus crispus), which is a red seaweed with different properties, nor with reindeer moss (Cladonia rangiferina), which is another lichen species with different constituents.

Image source and license: https://commons.wikimedia.org/wiki/File:Fermansbo-6101.jpg.
Modified by Peter Jorgensen.

Bioactive Compounds

Icelandic moss contains several bioactive compounds, including polysaccharides (particularly lichenan and isolichenan), phenolic compounds (such as protolichesterinic acid and fumarprotocetraric acid), and various secondary metabolites including usnic acid. These compounds are believed to be responsible for the medicinal properties attributed to this lichen.

Evidence-Based Health Benefits

Research on Icelandic moss has demonstrated several potential health benefits, though it's important to note that many studies are preliminary, conducted in vitro or in animal models, with fewer robust clinical trials in humans:

• Respiratory conditions: Multiple studies support its use for cough, bronchitis, and throat irritation due to demulcent and mild antimicrobial properties.
• Immunomodulatory effects: Polysaccharides found in C. islandica have shown potential to modulate immune responses in preclinical studies.
• Antimicrobial activity: In vitro studies demonstrate activity against certain bacteria and fungi, attributed to usnic acid and other compounds.
• Anti-inflammatory properties: Several studies indicate potential for reducing inflammatory markers, though clinical evidence remains limited.
• Antioxidant effects: Phenolic compounds in the lichen show free radical scavenging activity in laboratory studies.

Conditions with Limited Supporting Evidence

It's crucial to note that Icelandic moss has not been conclusively proven to "cure" any medical condition. However, research suggests potential benefits for:

• Upper respiratory tract infections (symptomatic relief)
• Dry cough and irritated throat membranes
• Mild inflammatory conditions of oral and pharyngeal mucosa
• Digestive complaints (based primarily on traditional use)
• Appetite stimulation in convalescence (based primarily on traditional use)

Traditional uses suggests broader applications, but scientific evidence primarily supports its use for respiratory complaints, and as a mild antimicrobial agent. The analysis noted significant heterogeneity in study designs and outcomes, highlighting the need for more standardized research.

Recommended Dosages

Dosage recommendations vary based on preparation method and intended use:

• Dried herb: 2-4 g three times daily (typically as tea or decoction)
• Fluid extract (1:1): 2-4 ml three times daily
• Tincture (1:5): 5-10 ml three times daily

Most commercial preparations are not standardized to specific active compounds, which presents challenges for consistent dosing. When standardization exists, it typically focuses on polysaccharide content (approximately 50-60% of dry weight) or usnic acid content (varying between 0.1-0.5% depending on harvesting conditions).

Studies on Higher Dosages

Limited research exists exploring doses significantly above the ranges mentioned. Higher concentrations of Icelandic moss extract (up to 10g daily equivalent) have provided no additional therapeutic benefit for respiratory symptoms, but have slightly increased incidence of gastrointestinal discomfort. This suggests a potential therapeutic ceiling, though significant knowledge gaps remain regarding optimal dosing protocols. More research is needed to establish clear dose-response relationships for specific conditions.

Side Effects and Contraindications

Icelandic moss is generally considered safe when used as directed, but potential adverse effects include:

• Gastrointestinal irritation (particularly at higher doses)
• Allergic reactions (rare)
• Potential for irritation of mucous membranes if used in very concentrated forms

Contraindications include known hypersensitivity to lichens or their components. Due to limited safety data, use during pregnancy and lactation is not recommended. Theoretical concerns exist regarding potential interactions with medications for hypothyroidism due to iodine content in some lichen specimens, though clinical significance remains unconfirmed.

Pharmaceutical Products

Few standardized pharmaceutical products containing Icelandic moss are available globally.

• Isla Moos®: Lozenges containing standardized Icelandic moss extract for throat complaints

This, and other products, are primarily available in European markets and are registered as traditional herbal medicinal products rather than prescription pharmaceuticals. No synthetic homologues specifically based on Icelandic moss compounds have achieved widespread clinical use, though research into isolated compounds (particularly usnic acid derivatives) continues.

Regulatory Status

The European Medicines Agency (EMA) has assessed Icelandic moss as a traditional herbal medicinal product for the symptomatic treatment of oral and pharyngeal irritation associated with dry cough. In the United States, the FDA has not approved specific health claims for Icelandic moss, though it is available as a dietary supplement.

Research Gaps

Significant research gaps remain, including:

• Limited high-quality clinical trials in humans
• Inconsistent standardization of extracts across studies
• Incomplete understanding of mechanisms of action
• Limited pharmacokinetic data on active compounds
• Minimal investigation into potential drug interactions

Conclusion

While traditional use and preliminary research suggest potential benefits of Icelandic moss for respiratory conditions and as an antimicrobial agent, robust clinical evidence remains limited. Most applications are based on traditional use rather than conclusive scientific validation. Further research, particularly well-designed clinical trials with standardized preparations, is needed to fully evaluate its therapeutic potential.

References

Freysdottir, J., Omarsdottir, S., Ingólfsdóttir, K., Vikingsson, A., & Olafsdottir, E. S. (2008). In vitro and in vivo immunomodulating effects of traditionally prepared extract and purified compounds from Cetraria islandica. International immunopharmacology, 8(3), 423-430.

Gülçin, İ., Oktay, M., Küfrevioğlu, Ö. İ., & Aslan, A. (2002). Determination of antioxidant activity of lichen Cetraria islandica (L) Ach. Journal of ethnopharmacology, 79(3), 325-329.

Meli, M. A., Desideri, D., Cantaluppi, C., Ceccotto, F., Feduzi, L., & Roselli, C. (2018). Elemental and radiological characterization of commercial Cetraria islandica (L.) Acharius pharmaceutical and food supplementation products. Science of the Total Environment, 613, 1566-1572.

Sánchez, M., Ureña-Vacas, I., González-Burgos, E., Divakar, P. K., & Gómez-Serranillos, M. P. (2022). The genus Cetraria s. str.—a review of its botany, phytochemistry, traditional uses and pharmacology. Molecules, 27(15), 4990.

Vladimirova, I. N., & Georgiyants, V. A. (2013). Extracted compounds from Cetraria islandica. Chemistry of Natural Compounds, 49, 347-348.