Lichen Islandicus
Also known as: Lichen islandicus, Iceland moss, Cetraria islandica
Overview
Cetraria islandica, commonly known as Lichen islandicus or Iceland moss, is a lichen species traditionally used as a herbal medicine and food supplement, primarily harvested from cold northern climates. It is recognized for its use in addressing loss of appetite, irritation of mucous membranes of the mouth and throat, and respiratory conditions such as cough and cold. Its primary active constituents are polysaccharides, mainly lichenan and isolichenan (β-D-glucans), which constitute 25-50% of its composition, alongside phospholipids, sterols, carotenoids, and lichen acids. The European Medicines Agency (EMA) has acknowledged its traditional use, particularly for appetite loss and mucous membrane irritation, though robust clinical trial evidence is limited. Research maturity is moderate, with some in vitro and limited clinical data, but a lack of high-quality systematic reviews or meta-analyses on its clinical efficacy in humans.
Benefits
Lichen islandicus has several traditionally recognized benefits, supported by the EMA, including appetite stimulation, likely due to its bitter lichen acids. It is also used to relieve irritation in the mouth and throat mucosa and to support symptoms of cough and cold. In vitro studies have demonstrated antioxidant activity, showing moderate free radical scavenging. Some in vitro research also indicates moderate anticancer effects against certain cancer cell lines (e.g., FemX and LS174), with IC50 values around 22-34 µg/ml, although these effects are less potent than standard chemotherapy agents like Cis-DDP. While general lichen extracts show antimicrobial and antifungal potential, Cetraria islandica specifically has been less studied in this regard. Clinical evidence from randomized controlled trials (RCTs) is largely absent, meaning most benefits are inferred from traditional use and preclinical data.
How it works
The primary mechanism of action for Cetraria islandica involves its polysaccharide content, specifically lichenan and isolichenan. These polysaccharides are believed to form a protective mucilage layer, which helps to soothe and protect irritated mucous membranes in the mouth, throat, and gastrointestinal tract. The bitter lichen acids present in the plant are thought to stimulate appetite by interacting with gustatory receptors. Its antioxidant properties are attributed to phenolic compounds that scavenge free radicals, thereby reducing oxidative stress. While not extensively studied for Cetraria islandica specifically, other lichen secondary metabolites may contribute to antimicrobial effects by disrupting microbial cell walls or metabolism. Due to limited absorption and bioavailability data, the polysaccharides are likely to exert their primary effects locally within the gastrointestinal tract rather than systemically.
Side effects
Cetraria islandica is generally considered safe, with no reported side effects based on traditional use and assessments by the European Medicines Agency (EMA). No significant adverse effects or drug interactions have been documented in the available literature. While specific contraindications are not well-defined, standard caution should be exercised for individuals with known allergies to lichens or related substances. There are no reported toxicological concerns, and its safety profile appears favorable. However, due to the lack of extensive clinical trials, comprehensive data on potential rare side effects or interactions with specific medications are limited. Users should consult a healthcare professional if they have pre-existing conditions or are taking other medications.
Dosage
Traditional dosing for Cetraria islandica typically ranges from 4 to 6 grams daily. This dosage is commonly administered as infusions or pastilles. There is no established maximum safe dose derived from clinical trials, as robust clinical research in this area is limited. The timing of administration is flexible and often aligns with symptomatic periods, such as when experiencing appetite loss or irritation of mucous membranes. The specific preparation form, whether an infusion, extract, or pastille, may influence both the bioavailability of its active compounds and patient compliance. Due to the lack of extensive clinical data, it is advisable to adhere to traditional usage guidelines or consult with a healthcare professional for personalized dosage recommendations.
FAQs
Is Lichen islandicus effective for cough and cold?
Traditional use supports its role in providing symptomatic relief for cough and cold, particularly for soothing irritated mucous membranes. However, high-quality randomized controlled trials confirming its efficacy are lacking.
Are there any safety concerns with Lichen islandicus?
No significant safety concerns or adverse effects have been reported in traditional use or regulatory assessments by the EMA. It is generally considered safe.
How quickly do the effects of Lichen islandicus appear?
The onset of effects is not well documented. Traditional use suggests symptomatic relief during acute phases, particularly for soothing irritation, but individual responses may vary.
Can Lichen islandicus be combined with other herbal medicines?
There are no known contraindications for combining Lichen islandicus with other herbal medicines. However, clinical data on such combinations are limited, so caution and professional advice are recommended.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4158017/ – This in vitro study investigated the antioxidant and anticancer effects of a methanol extract of Cetraria islandica. It found moderate free radical scavenging activity and significant growth inhibition of human cancer cell lines (FemX and LS174) with IC50 values of 22.68 and 33.74 µg/ml, respectively. The extract was less potent than cisplatin but demonstrated statistically significant activity (p<0.05), suggesting potential therapeutic applications, though no clinical data were included.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9325835/ – This meta-analysis reviewed lichen substances as antifungal agents, highlighting the broad antimicrobial potential of various lichen species. While it underscored the efficacy of lichen extracts against fungi like Fusarium spp., Cetraria islandica was not a primary focus of the study, and it did not provide clinical trial data specific to Cetraria islandica's antifungal properties.
- https://www.ema.europa.eu/en/documents/herbal-report/final-assessment-report-cetraria-islandica-l-acharius-sl-thallus-first-version_en.pdf – This EMA HMPC monograph (2014) provides a comprehensive assessment of Cetraria islandica, concluding that preparations are plausible for traditional use in appetite loss and mucous membrane irritation. The report notes no reported side effects but emphasizes that the assessment is based on traditional use and limited pharmacological data, rather than robust clinical trials, highlighting the need for further research.
- https://www.ema.europa.eu/en/medicines/herbal/lichen-islandicus – This EMA page provides an overview of Lichen islandicus, confirming its status as a traditional herbal medicinal product. It reiterates the recognized traditional uses for appetite loss and irritation of mucous membranes, aligning with the HMPC monograph. The page serves as a regulatory reference for its traditional use and safety profile.
