Fomes fomentarius is a fungus whose perennial, woody fruiting body is often shaped like a horse’s hoof, hence one of its common names, hoof fungus. Fomes fomentarius also goes by the names Tinder Conk, Tinder Fungus, Tinder Polypore and Ice Man Fungus. It grows wild throughout northern North America and parts of Eurasia, as well as in the cooler areas of Africa[i]. While it has no close relatives in North America, there are several other members of the genus in Eurasia. While it is not edible, it is useful[ii].
Many of the uses of F. fomentarius involve a felt-like material called amadou made from the flesh of the fruiting body. Amadou is highly absorbent and was once used in both medicine and dentistry, as well as to mount insect collections and make pin cushions able to prevent the pins from rusting. It is still used to make hats. If pre-treated with either urine or potassium nitrate (which can be made from animal urine), amadou makes excellent tinder, as it becomes both highly flammable and able to burn hot for a very long time. This last use accounts for both its scientific name (which translates to “tinder used as tinder”) and another of its common names, tinder polypore.
- fomentarius also has a long history of medicinal uses, some of which are being confirmed by scientific study.
Fomes fomentarius Identification and Description
Cap: shell- or hoof-shaped, usually with narrow bands of gray and gray-brown around the upper surface. Some are silver-gray or almost black.
Pore surface: whitish or brownish.
Spore color: yellowish white
Habitat: living or dead hardwoods in cool or temperate climates
Fomes fomentarius looks quite different than most familiar mushrooms[iii]. It has no stem or stipe, nor does it have gills, but instead a flat lower surface covered with pores, which are the openings of densely-packed, spore-producing tubes. The fruiting body is perennial, adding a new layer of tubes every year, and so the flesh is tough and woody. And while many stipeless, pore-bearing fungi have the same shelf-like shape as a young F. fomentarius fruiting body, older examples develop a horse-hoof shape that is very distinctive. It feeds on either living or dead hardwoods, especially birch and beech, with the fruiting body emerging from the side of the trunk.
Fomes fomentarius closely resembles another species, Phellinus igniarius, to the point that the latter is sometimes called false tinder fungus (confusingly, F. fomentarius is sometimes also called “false tinder fungus”). P. igniarius has traditional uses of its own, notably as a chewing-tobacco additive[iv] (a practice now considered dangerous, as it increases the absorption of nicotine), but it should not be confused with F. fomentarius. The most obvious difference between the two is spore color.
Fomes fomentarius Benefits and Uses
While amadou felt made from F. fomentarius has been used in medical contexts to absorb blood and other fluids, it is the internal use of extracts of the fruiting body that are more properly termed medicinal. Uses in traditional folk medicine and by modern herbalists include the following[v]:
- Cures hemorrhoids
- Treats bladder disorders
- Treats dysmenorrhea
- Acts as a diuretic
- Acts as a laxative
- “Steadies nerves” (this might mean that it treats anxiety)
- Treats stomach cancer
- Treats uterine cancer
However, the efficacy of folk cures can be hit or miss; for every one that is proven useful when tested, there might be another that proves unhelpful or even harmful. Modern scientific research on F. fomentarius has focused less on testing the folk treatments themselves and more on exploring and testing certain chemical constituents of the fungus that are likely to have medicinal properties.
The properties of such chemical constituents include:
- Anti-inflammatory properties
- Antiviral activity
- Antibacterial activity
- Antitumor activity
- Anti-diabetes effects
- fomentarius contains substances thought to have an anti-cancer effect. Accordingly, an extract of the fungus has been tested both on cultured cell lines and on living mice deliberately given sarcoma. In both cases, the extract limited the growth of cancer cells when given at doses above a certain threshold level[vi]. Another study looked at cultured cell lines of certain human breast cancers and found that an extract of F. fomentarius both killed the cancer cells and made them less motile[vii].
Extracts of several different mushroom species, including F. fomentarius, were tested against the herpes simplex virus. Prior to testing, the researchers established safe doses of the extract, allowing them to test for antiviral activity only at doses that would be safe if used in a patient. F. fomentarius was one of the species that showed activity against the virus[viii]. F. fomentarius was also one of several species shown able to combat certain influenza strains[ix].
The chemical substance, fomentariol, is known as a potential treatment for diabetes and can be extracted from F. fomentarius[x].
Other Potential Benefits
- fomentarius showed the most antioxidant and antibacterial activity of any of several fungi tested, in a study conducted using chemical analysis only[xi]. In both cultured mouse cells and in actual living mice, a substance extracted from F. fomentarius improved certain aspects of immune function[xii]. One study looked at analgesic and anti-inflammatory effects of an extract of F. fomentarius in mice and rats, not only to confirm that such effects exist, but also as a means of investigating the mechanism behind the effects[xiii].
Fomes fomentarius Dosage
Few, if any, of the studies involving F. fomentarius have involved the whole mushroom; they have instead involved various extracts or isolated chemicals derived from the mushroom. While some of the study results involved dosage information, that information refers to the specific product used in the study (and also to the study animal), and might not apply to a different F. fomentarius products.
- fomentarius extracts are available commercially[xiv], but they are not necessarily equivalent to any of the products used in the studies. It is therefore difficult to say what the optimum dose should be. Given the early stage of most research on the subject, it is best to rely on the judgment of a qualified healthcare practitioner for information about proper dosage.
Fomes fomentarius Side Effects, Safety and Toxicity
There is little published information on potential safety concerns relating to F. fomentarius use, which could be taken to mean that medicinal use of the fungus is safe, but is hardly a guarantee. The fruiting body is generally described as inedible, but it is not described as poisonous or toxic. Most likely, it is the woody texture and acrid taste that prevent it from being table fare, not any actual danger.
Users should still exercise caution, however, since there could be unknown risks, and even generally safe fungi could still cause allergies or over-sensitivities in some individuals. It is also important to buy from a reputable provider, to protect against the possibility of accidental mislabeling.
[i] (2019). Fomes fomentarius, Tinder Conk Mushroom, Tsuriganetable. Retrieved on October 4, 2019.
[v] (2019). Fomes fomentarius, Tinder Conk Mushroom, Tsuriganetable. Retrieved on October 4, 2019.
[vii] Lee, S.O., Lee, M. H., Lee, E.O., Lee, H.J. (2019). Fomes fomentarius Ethanol Extract Inhibition of Cell Growth and Motility Induction of Apoptosis via Targeting AKT in Human Breast Cancer MDA-MB-231 Cells. International Journal of Molecular Sciences. 20(5).
[ix] Krupodorava, T., Rybalko, S., Barshteyn, V. (2014). Antiviral Activity of Basidiomycete Mycelia Against Influenza Type A (Serotype H1N1) and Herpes Simplex Virus Type 2 in Cell Culture. Virologica Sinica. 29(5).
[x] Maljurić, C., Golubović, J., Ravnikar, M., Žigon, D., Štrukelj, B., Otašević, B. (2018). Isolation and Determination of Fomentariol: Novel Potential Antidiabetic Drug from Fungal Material. Journal of Analytical Methods in Chemistry.
[xi] Karaman, M., Stahl, M., Vulić, J., Vesić., M., Canadanović-Brunet, J. (2014). Wild-growing Lignicolous Mushroom Species as Sources of Novel Agents with Antioxidative and Antibacterial Potentials. International Journal of Food Sciences and Nutrition. 65(3).
[xii] Gao H.L, Lei, L.S., Yu, Z.G., Chen. N.N., Wu S.G. (2009). Immunomodulatory Effects of Fomes fomentarius Polysaccharides: An Experimental Study in Mice. Journal of Southern Medical University. 29(3).
[xiii] Park., Y.M., Kim, I.T., Choi, J.W., Park, K.Y., Lee, J.D., Nam, B.H., Kim, D.G., Lee, J.Y., Lee, K.T. (2004). Anti-inflammatory and Anti-nociceptive Effects of the Methanol Extract of Fomes fomentarius. Biological and Pharmaceutical Bulletin. 27(10).
[xiv] Tinder Fungus Extract—Wholesale. Retrieved on October 6, 2019.