Ganoderma lucidum, is an interesting shelf fungus that is important as a medicine in the Far East, in places such as China, Japan and Korea. G. lucidum is of particular interest because it has been portrayed as a "fix-it-all" herbal remedy for maladies such as: HIV, cancer, low blood pressure, high blood pressure, diabetes, rheumatism, heart problems, paralysis, ulcers, asthma, tiredness, hepatitis A, B, and C, insomnia, sterility, psoriasis, mumps, epilepsy, alcoholism, and the list goes on. These claims are mostly made by the people who are selling G. lucidum herbal supplements, but G. lucidum, also known as Reishi, ling chih, and ling zhi has a long history of being used as an herbal remedy. We will get to that later.
First, how do you identify Ganoderma lucidum? Ganoderma is a member of the Polypores, a group of fungi characterized by the presence of pores, instead of gills on the underside of the fruiting body. G. lucidum, considered by many mycophiles to be one of the most beautiful shelf fungi, it is distinguished by its varnished, red surface. When it is young it also has white and yellow shades on the varnished surface, differing from the dull surface of Ganoderma applanatum, the artist's conk. G. lucidum is a saprophytic fungus that tends to grow more prolifically in warm climates on decaying hardwood logs and stumps. This feature helps to distinguish it from a similar looking Ganoderma tsugae, which also has a beautiful red varnished surface, but only grows on the stumps and logs of conifers, especially hemlock (as you might guess from the name). Another distinguishing characteristic is the flesh of G. tsugae is white whereas the flesh of G. lucidum is brown. Besides the shelf form, both G. tsugae and G. lucidum can be stalked. The spore prints of both species are brown and the spores are very similar in size and shape.
Ganoderma curtisii is considered by some mycologists to be a different species because of its brighter yellow colors and geographic restriction to the southeaster United States. However, most consider Ganoderma. lucidum and G. curtisii to be the same species because of their similar appearance and habitats; they both prefer to grow on hardwoods. In "North American Polypores," practically the bible for wood-decaying poroid fungi, Gilbertson and Ryvarden, do not consider G. curtisii a species separate from G. lucidum. Another fungus that resembles G. lucidum is Ganoderma oregonense, which, like G. tsugae grows on conifers, but is found in the Pacific Northwest and New Mexico. G. oregonense can get up to 1 meter across and has slightly larger spores than G. lucidum and G. tsugae. There are arguments that these four separate species (G. lucidum, G. tsugae, G. curtisii, and G. oregonense) should be considered one species. The reasons for keeping them apart are primarily due to the host specificity of each fungus. Interestingly, if given only either hardwood or conifer wood in culture, each of the four species can grow and produce fruiting bodies, despite their natural occurrence on only one of those substrates.
In 1995, Moncalvo, Wang and Hseu, isolated the DNA of G. tsugae and G. lucidum and found that it was hard to tell the difference between the two species. An even more recent study in 2004 by Hong and Jung, found that G. lucidum from Asia was in its own group, whereas, G. lucidum from Europe and the Americas was more closely related to G. tsugae. Clearly, further investigation into the molecular make up of these two species is needed. For more information about the relationships of the species Ganoderma For more information, see these papers: Moncalvo, J.M., Wang, H. H. & Hseu, R. S. (1995). Phylogenetic relationships in Ganoderma inferred from the internal transcribed spacers and 25S ribosomal DNA sequences. Mycologia 87: 223-238, and Hong, S.G., Jung, H. S. (2004) Phylogenetic analysis of Ganoderma based on nearly complete mitochondrial small-subunit ribosomal DNA sequences. Mycologia 96: 742-755.
Ganoderma lucidum, considered rare and hard to find in nature in China and Japan, is now commonly cultured. It can be cultured on logs that are buried in shady, moist areas. G. lucidum can also be inoculated onto hardwood stumps. Under commercial cultivation conditions, G. lucidum is normally grown on artificial sawdust logs, as shown to the right. We'll cover this cultivation method in more detail in a later Fungus of the Month. Other methods of cultivating G. lucidum and many other fungi can be found in Paul Stamets' book, "Growing Gourmet and Medicinal Mushrooms"
Now let's look at the medicinal uses of G. lucidum or Reishi. If you feel the fruiting bodies, you'll notice that they're very hard, so no one tries to eat them like most (softer) mushrooms-- too tough! It has been used as an herbal remedy for such things as health, recuperation, longevity, wisdom and happiness for centuries in Asian traditional medicine. The first historical mention of G. lucidum was during the rule of the first Chinese emperor, Shin-huag of the Ch'in Dynasty, when the fungus's medicinal uses are first described. In fact, a Reishi Goddess, known as Reishi senshi, was worshipped because she would bestow health, life and eternal youth.
There are two different types of Reishi, the traditional wide, shelf-like fruiting body and the antler shape, known as Rokkaku-Reishi. The antler shape arises from varying carbon dioxide levels and low light. These two types are rumored to have different healing characteristics. Recently, there have been a large amount of scientific papers published with experiments attempting to quantify the effect of G. lucidum on the human body. The fungal extract has been shown to act on immune system cells, to work against herpes virus, to lower cholesterol and stop cell proliferation.
Unfortunately, while reading these papers it seems important to remind you that we are still not sure if G. lucidum and G. tsugae are separate species.
Although the molecular make up has yet to be determined conclusively, several biologically active compounds from G. lucidum have been characterized. These include adenosine, said to have an analgesic effect, R,S-ganodermic and ganasterone that have an antihepatoxic effect, and glucans and polysaccharides that are responsible for the anti-inflammatory and antitumor properties of G. lucidum.
Something else to keep in mind is that all these experiments were done in cell lines, mice, rats and hamsters. So far no large scale unbiased human trials have yet been performed, and the FDA does not yet approve use of Reishi as medical treatment. In order to gain FDA approval, purified compounds from G. lucidum would have to go through an intensive amount of screening in cell lines and animals; much of this pre-clinical testing has already been performed. The next step would be a phase one clinical trial, which assesses the potential drug's safety. Healthy volunteers are paid to take the drug for a certain amount of time, and the compound is studied for its absorption into the body, its metabolism, and its excretion. Once the potential drug passes phase one, which can take up to several months, it moves on to phase two. In phase two, several hundred patients participate in what is called a double blind clinical trial, in which both the patient and the physician are unaware of whether the patient is receiving the potential drug or a placebo . Phase two can last from several months up to several years. If the potential drug is proven effective after phase two, it moves to phase three. Phase three also consists of blind clinical trials, but on a much larger scale. This phase is used to understand the drug's effectiveness, benefits, and the range of possible adverse reactions. Without a doubt, G. lucidum and its researchers have a long road ahead of them before they can prove the mushrooms healing powers.
I hoped you enjoyed learning about Ganoderma lucidum, its relatives and potential uses. Although these species of fungi can produce beautiful fruiting bodies, who would have expected them to hold so many potentially useful chemicals?
This month's co-author is Kathleen Engelbrecht, one of my students in Mycology, Medical Mycology, and Advanced Mycology. She's working on an interesting project looking for potentially useful compounds from fungi.
If you have anything to add, or if you have corrections, comments, or recommendations for future FotM's (or maybe you'd like to be co-author of a FotM?), please write to me at email@example.com
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