There are few mushrooms as well-regarded as reishi. The medicinal mushroom is beginning to catch the attention of the English-speaking wellness world—but they’re certainly nothing new. Reishi mushrooms have a long and rich cultural history, starting in Asia over 2000 years ago. In this article, we’ll consider the basics of all-things reishi, from its history, potential reishi mushroom benefits, how to identify reishi in the wild, and even tips on how to grow your own.
What is Reishi (Ganoderma)?
Reishi is the common name given to a number of mushrooms in the genus Ganoderma, a word that describes the polypore’s shiny cap. The Ganoderma genus contains around 80 known mushroom species worldwide. Yet, despite their widespread habitats, the use of reishi mushrooms in natural medicine originated in Eastern Asia, where they feature a long history of human use. English speakers tend to borrow the Japanese word to describe these mushrooms—reishi—but the word is originally adapted from the Chinese word lingzhi (meaning “spirit mushroom”).
The official Chinese compendium of drugs, the Chinese Pharmacopoeia, recognizes only Ganoderma lucidum (chizhi or red reishi) and Ganoderma sinense (zizhi or black reishi), but around 20 species are used commercially in China alone. Additionally, reishi is not limited to red and black coloration: The fungus’ coloration can vary between species and under different growing conditions. Some Ganoderma species—G. curtisii—feature orange and yellow coloration. Yet, “real reishi” often refers to G. lucidum and G. sinense alone.
Distinguishing one Ganoderma from another is not always the easiest of tasks. While your average home mushroom grower or wellness enthusiast might not be expected to have a detailed understanding of reishi’s complicated taxonomy, even commercial mushroom producers don’t always get it right either. An investigation into both mushroom grow kits and herbal supplement products found that reishi mislabelling is a common occurrence.
Reishi Mushroom History
Reishi is one of the most commonly depicted mushrooms across Eastern Asia: The mushroom was used as a herbal remedy for over 2000 years in China, Japan, and Korea. The fungus appears in books, paintings, carvings, and furniture. In some traditions, reishi mushrooms were hung above doorways to keep bad spirits from entering. Depictions of what have been interpreted as reishi proliferated in Taoist art of the 15th century, where the mushrooms were featured in portraits of Chinese high society and religious depictions.
Historians have also found reishi referenced in Chinese pharmaceutical texts from as early as 200-250 CE, where reishi’s reputation as a herbal remedy may have been enhanced by its association with privileged members of Chinese society. The Bencao Gangmu—written during the Ming dynasty—claims that ancients ate reishi to achieve immortality. Author Robert Rogers writes that in traditional Chinese medicine, “reishi is considered warming, astringent, nourishing, detoxifying, and of course, tonifying.”
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Reishi Mushroom Benefits
Reishi is perhaps among the most well-known medicinal mushrooms in human society. Its history of medicinal use is well-documented in Traditional Chinese Medicine (TCM) and is widely used by TCM and conventional medical practitioners in China. The Chinese Pharmacopoeia states that reishi acts to replenish vital force, ease the mind, and relieve coughs and asthmatic symptoms. As such is recommended for treating dizziness, insomnia, palpitation, and shortness of breath.
Yet, although the mushroom has a millennia-long history in human medical practice, modern scientific research on reishi mushroom benefits is still ambiguous. Reishi mushrooms are perhaps most commonly touted for their potential effects on the human immune system. Medicinal mushrooms like reishi contain beta-glucans and triterpenes, compounds that may provide health and nutritional benefits. Glucans are fibers that help provide structure to cell walls in bacteria and fungi. Fungal glucans—specifically beta-glucans—are currently being studied for their immuno-modulating properties; qualities which make them compounds of interest as dietary additions in cancer treatment.
Despite its rapidly growing popularity in the international wellness industry, many reishi health claims—including reishi mushrooms’ effectiveness for cancer—are still poorly supported in modern-day scientific studies. Though some health claims have been supported in studies with cells grown in the lab or in animal testing, experiments in human populations have been less conclusive and often small in size. Additionally, understanding any of the benefits of reishi mushrooms becomes even more difficult when we consider all the different species that may be marketed under the name “reishi.”
It is important to note that some medical organizations such as Memorial Sloan Kettering Cancer Center only recommend reishi as a complementary supplement to more established treatments, and not as a replacement. Documented side effects of reishi include nausea, insomnia, and liver damage. While reishi is generally considered to be non-toxic, supplements should be obtained from reputable sources—or grown yourself. You should always have a conversation with your physician if you’re considering using reishi or any other herbal supplement to aid treatment of a diagnosed medical condition.
Reishi Mushroom Dosage
Human beings have been eating reishi for thousands of years—but how much should you really take? Reishi extracts and powders can be more concentrated than fresh reishi, dried reishi, and reishi teas. Similarly, beta-glucan and triterpene content varies in different Ganoderma species—and even varies between each individual mushroom. As such, consistently dosing reishi is not the easiest task.
How Many Mg of Reishi Mushroom Should I Take?
The answer to this question is a difficult one: There is currently no scientific evidence on either the effective or safe dose of any of the Ganoderma species that fall under the name reishi. What we do know about typical dosages comes from Chinese herbal remedy texts. For this reason, it’s always recommended to follow package directions for reishi products or talk with your medical provider to gain insight into how much reishi you should take.
Read: Our Guide to Medicinal Mushrooms
How Much Reishi per Day?
It’s always best to follow package directions and your medical practitioner’s advice. For those of you who might have grown or foraged your own reishi, the typical dosages in traditional Chinese medicine reishi range from 1.5 to 9 grams per day. A sensible starting dose might begin at around 300-500 milligrams (0.3-0.5 grams) per day for a few weeks to see how you feel, keeping in mind that “more” doesn’t always equate to “better.” Dosage will also depend on whether you’re taking extracts or capsules.
Reishi Extract Dosage
Reishi extracts are usually prepared by adding ground dried mushrooms (or mycelium) to hot water or alcohol. It’s important to note that extracts may vary in strength, in which case you might need to adjust your dosage accordingly. As no high-quality scientific data exists for any reishi preparation, we recommend following the advice above for daily intake.
Reishi Capsules Dosage
Though hot water extracts are a more traditional preparation, reishi capsules are becoming much more common. These capsules may simply contain dried mushroom powder, dried mycelium, spores, or even dried extract. In all of these different preparations, the combination of chemical compounds may vary widely, but general daily dosage advice should apply here as well.
How To Identify Reishi Mushrooms
Though reishi as a group are easily identified, getting down to the exact species can be difficult even for the most experienced mushroom hunters. Here we’ll cover some common reishi features, as well as those mushrooms that look similar but fall outside the group.
Reddish-brown reishi mushrooms are commonly found growing in fan, hoof, or kidney shapes on both living and dead trees. Reishi can be found at any time of year, as the mushrooms form woody brackets or “conks” that don’t easily rot away.
The word for the genus that reishi represents comes from the Greek words ganos (shining) and derma (skin), so use this feature to aid in your identification. The shiny (laccate) caps and stems of reishi can often be hidden by a thick layer of brown spores that tend to cover mature mushrooms.
Pay Attention to the Reishi Underside
Reishi belong to a group of fungi called polypores, so-called due to the many small holes (pores) on the underside and edge of the mushroom, from which the spores emerge. In most species this surface can be white, cream or gray in color, which may turn brown as the mushroom matures.
In species like the artist’s conk (G. applanatum) and southern bracket (G. australe), this light-colored surface bruises brown, allowing those of a more creative inclination to draw pictures across their surface.
Reishi Look-alikes
Other polypore mushrooms can sometimes be mistaken for reishi, but fledgling foragers will be pleased to know that there are no poisonous look-alikes. Reishi may sometimes be confused with other polypore fungi, in particular the red-belted polypore in the genus Fomitopsis. One of the easiest ways to distinguish this species from reishi is with a spore print. Red-belted polypore has white spores, compared to those of reishi which are always brown.
Reishi Mushroom Cultivation
In the study mentioned earlier, over half of mycelium cultures sold as red reishi (G. lucidum) actually contained other Ganoderma species that were non-native to the United States. Introducing non-native species to an area can have negative effects on native ecosystems, and non-native southern bracket (G. adspersum) has been documented to infect Californian almond trees more aggressively than native species, damaging trees and harming overall crop yield.
If you’re considering an outdoor grow, try to find native species—either from reputable vendors or by cloning wild species nearby. Not only will you have a better chance of growing a species that is used to your local climate, but you’ll also be safe in the knowledge that you’re not accidentally introducing potentially harmful alien species into the wild.
Read: Why You Should Grow Your Own Mushrooms
How Long Does Reishi Take To Grow?
In the wild, these mushrooms tend to grow slowly, due to seasonal environmental changes. For those wanting to grow reishi at home, the quickest method is to inoculate substrate bags and fruit them indoors, which will yield mushrooms in about three months.
Another option is to grow reishi outdoors on logs or from substrate blocks buried in the ground. Buried blocks can fruit as quickly as indoor cultivated reishi if conditions are perfect, but logs can take up to a year or two of care before producing mushrooms.
Reishi Fruiting Conditions
Reishi tolerates a range of temperatures, though they grow most quickly around 70-80°F (21-27°C). A slight drop in temperature 65-75°F (18-24°C) may encourage pinning in some species. As with most mushroom species a high humidity is essential for fruiting, though more mature mushrooms can tolerate periods of 90 percent humidity or less/
Carbon dioxide (CO2) levels are a crucial factor in encouraging different forms of growth. Reishi’s antler form is caused by high CO2 levels, whereas the more natural fan-shaped form of reishi is caused by lower CO2. Some skilled growers are able to create beautiful varied growth forms by adjusting fresh air levels in their growing chambers at various stages of the process.
Best Reishi Substrate
Like many other fungi, reishi mycelium will happily grow on grains like rye millet or wheat. To produce mushrooms woody bulk substrates (chips, sawdust, or whole logs) are essential. The reishi mushroom benefits from supplementary bulk oat, wheat, or rice bran substrate bags, which can be used to improve yield. It is not recommended to use more than around 15 percent for best results.
When To Harvest Reishi Antlers
Reishi can be harvested at any stage of their growth—one of the benefits of reishi as a cultivated mushroom. So, feel free to experiment with different harvesting times. However, keep in mind that reishi’s high spore production (up to 30 billion spores per day in some species) can be a particular problem when growing these mushrooms indoors. Mushroom spores have been associated with breathing difficulties—so keep a close eye on your indoor grows and try to harvest before spores are released.
