The Medicinal Potential of Reishi Fungus

Over the last 30 years, mushrooms have exploded in popularity across the world. [1] In 1997, the average person consumed 1 kilogram of mushrooms per year, today the average is 4.7 kilograms. This constitutes a 30x increase in three decades, with more than 34 million metric tonnes of mushrooms sold across the world every year. This is especially true in Asia, where 82.8% of mushrooms were produced as of 2020. [2] A major reason for this is that multiple Asian cultures value mushrooms as both a food source and as a powerful medicine in traditional healing remedies. While the taste of mushrooms is evident, new research is identifying exactly how these fungi improve health. 

The primary theory resides in the fact that in addition to multiple active ingredients, mushrooms also help to optimize various bodily functions through secondary metabolites. [3] The compounds within mushrooms help our bodies to work more efficiently, leading to an overall increase in health and well being. One of the best examples of this is one of the most ubiquitous mushrooms in Asia, the Ganoderma lucidum L.. In China, it is referred to as “Lingzhi,”  in Korea “Youngzhi,” and, most commonly, “Reishi” in Japan. Thanks to the biological and therapeutic benefits unique to this fungus, combined with their bioavailability, reishi mushrooms have some of the highest potential in the growing medicinal food supplement market.

Primary Medicinal Ingredients of Reishi Fungus

Most mushrooms are 90% water by weight, so all other special ingredients are found in the remaining 10%. Within that 10% for reishi mushrooms is a healthy mix of approximately 1.8% ash, 26–28% carbohydrate, 3–5% crude fat, 59% crude fiber, and 7–8% crude proteins, providing most of what the body needs in a single plant. [4] Beyond the complex variety of nutrients, though, are the medicinal compounds. 

There are more than 400 active compounds in reishi mushrooms, but the three most significant are polysaccharides, peptidoglycans, and triterpenes. [5] The ratios between these three materials depend on a few variables present during the fungus cultivation, including things like region, soil composition, and growth techniques. That being said, each compound demonstrates specific and quantifiable medical benefits. 

• Polysaccharides are some of the most heavily researched at the moment, having demonstrated benefits like immunomodulatory, antioxidant, antitumor, antiviral, anti-carcinogenic, and anti-inflammatory activities. [6] These compounds can be found throughout mushroom botanical material, and traditionally are extracted by boiling them in water and then precipitating them with either ethanol or methanol. Research is only getting started, but mushroom sourced polysaccharides are already being used in over-the-counter medications to treat cancer and liver diseases.

•  Peptidoglycans are important macromolecules that form a cytoplasmic membrane around crucial bacteria in the body. [7] Basically, they serve as a shield that helps protect bacteria thus allowing them to perform their functions better in the body. This also includes protection during the bacterial reproduction cycle, which can minimize bacterial mutation and may ensure healthy growth going forward. This is the key to the secondary benefits, but data indicates it may help with circulation, digestion, and immunity. Consuming reishi mushrooms protects the body’s microbiome.

• Finally, triterpenes are a class of terpenes which can provide both flavor and medical benefits to organic plant material. [8] In the case of triterpenes from reishi mushrooms, these compounds have been specifically tied to both anti-cancer and anti-diabetic effects. Combining this with the polysaccharides, this means that reishi fungus can potentially help to treat cancer in multiple ways, while also benefiting other organs like the liver and the pancreas. 

Research is still ongoing, though, so it may be difficult to isolate how much triterpenes help compared to polysaccharides. With this in mind, researchers are optimistic as they have already managed to classify more than 100 distinct triterpenes in reishi mushrooms, of which at least 50 are new and exclusively found in this fungus. [9] This means that with increased discoveries, recognized medical benefits may also expand.

Major Medical Benefits of Reishi Mushrooms 

Reishi mushrooms have more than 2000 years of medicinal use, but it is only recently that scientists have been able to prove the benefits associated with them. [10] Both polysaccharides and triterpenes serve as anti-cancer agents, but the way each one works against the cancer differs slightly. [11] Both can stop the spread of cancer, but polysaccharides do so through tumor apoptosis, limiting tumor angiogenesis, and scavenging for free radicals. This means they attack tumors that already exist, not only stopping their growth, but actively shrinking them.

Combining this with the search for free radicals, polysaccharides work like cancer hunters in the body. By contrast, triterpenes don’t attack the cancer directly, instead they block the signals targets within cancer cells that indicate the need for them to reproduce. This stops new cancer from forming, and may prevent its spread throughout the body. This means in the fight against cancer, triterpenes play defense by stopping cancer from growing and polysaccharides play offense by killing existing cancer cells. Together, they both combine into an effective natural remedy to augment cancer treatments, though it is difficult to determine which is more effective as they both work in tandem. 

Beyond cancer, these compounds have been shown to help multiple internal organs.[12] Polysaccharides can help the liver by clearing intestinal blockages, regulating fat metabolism, relieving oxidation and inflammation, and lowering insulin resistance. [13] Speaking of insulin, triterpenes can be useful in treating diabetes by helping to regulate glucose metabolism and prevent insulin resistance.[14] All of these have been identified through specific biological responses to these two compounds, but even more intriguing is how the body can benefit from the net effect associated with the third medicinal compound peptidoglycans. 

Secondary Medical Benefits through Improved Function

A car may have a great engine, but without oil to help each component part work together, a breakdown is inevitable. This is kind of like the way peptidoglycans work in the body. They function like oil in that their benefits are less specific, but they create a valuable cumulative effect. Though their benefits are not as quantifiable as the other two, these macromolecules protect a variety of bacteria within the body. These improved functions translate into an overall better wellbeing, which is certainly notable in several small, but specific, ways. 

The first, and possibly most significant, starts with the blood stream. Reishi mushrooms can help with the regulation of blood pressure, which, when elevated, contributes to more than 7.6 million deaths in the United States per year, or 13.5% of all fatalities in the country. [15] 

Reishi mushrooms have been shown to lower hypertension and lower hypercholesterolemia. [16][17] Both of these contribute to high blood pressure, but in two different ways. Hypertension relates to the size of the blood vessels. If they are too big, blood pressure builds through congestion in the arteries. The same is true of hypercholesterolemia, which is when cholesterol is too high. These also create blockages, but by making the pathways blood travels more narrow, not the blood vessels themselves. By helping bacterial function within the blood, the operating theory is that peptidoglycans help said bacteria to break down materials in the blood. This lowers blood pressure and improves blood flow. 

By increasing the functionality of the circulatory system, peptidoglycans may also help to explain why reishi mushrooms limit inflammation, but this is only the beginning. [18] Blood is the transportation network within the body. So if the circulatory system improves its efficiency, there are carryover benefits that factor into the immune system as well.[19] Take the case of HIV, which data indicates may be helped by peptidoglycans in reishi mushrooms. [20]

The precise mechanism is not known, but reishi fungus has been tied to an increased T-cell count, or immune cells produced by the thymus, which feed directly into the bloodstream. Improved circulation may stimulate production of these cells, but limiting unnecessary materials in the blood may also improve their functionality as well. This is the part that has not been clearly identified. 

The same may be true when looking at carryover effects for other diseases too. Take, for example, hepatitis, which relates to liver function. [21] The liver filters toxins out of the body, by way of the blood, that flows into and out of it. The theory goes that if blood is being pre-processed more efficiently, thanks to these peptidoglycans, before it reaches the liver, then liver function will also improve.

Basically, it does its job more easily, and when combined with the polysaccharide benefits to the liver, reishi mushrooms can effectively combat various liver diseases. This is what forms the basis for the theory of secondary metabolites that many researchers believe improves health overall. The theory promotes the idea that by increasing the body’s efficiency in several ways, larger functions also improve. 

So far, the evidence of this has only included mentions of the circulatory system, but there are other systems within the body that also rely on bacteria. One of the most significant of which is the digestive system. The average person has an estimated 100 trillion bacteria cells making up the microbiota in their digestive system. [22] Bacteria within the microbiota are essential in helping the body to break down and absorb vitamins, minerals, and nutrients from food. This may help to explain why reishi mushrooms are associated with digestive health as well. 

Traditional medicines have used reishi mushrooms as a treatment for both nausea and altitude sickness. [23][24] The aided digestion may be clear, but the carryover effect to digestion comes in the form of increase stamina and lowered fatigue. [25][26] 

These secondary benefits, which are also recognized in traditional medicines, may be a result of improved nutrient absorption. The logic applies that if peptidoglycans work to protect bacteria, it makes sense that they help digestive bacteria the same way they aid circulatory bacteria. They improve bacteria function indiscriminately, which allows the bacteria to work more efficiently and the whole system improves.

Basically, it’s a similar logic to a car’s higher performance just after an oil change. If everything in the body operates smoothly, whether it is the immune, circulatory, or digestive systems, then health improves overall. This is all thanks to the secondary metabolites that reishi mushrooms provide. 

Potential Risks Associated with Reishi Fungus

While reishi fungus does seem to provide many benefits, there are some potential negative side effects associated with them as well. First, considering they have the potential to lower blood pressure, reishi mushrooms may not be suitable for people who have low blood pressure or low platelet counts. Additionally, because reishi mushrooms have been shown to interact with both the liver and the pancreas, it may interfere with medications that are prescribed to treat diabetes, hepatitis, or HIV. 

It should also be stated that while reishi mushrooms can potentially help treat the above-mentioned conditions, health effects may vary, and they should not be seen as a replacement for any prescribed treatment. Depending on variables like age, medical conditions, and the specific variation of reishi fungus, there could be additional side effects as well. 

Patients should be especially wary of combining these fungi with aspirin, warfarin, heparin, or non-steroidal anti-inflammatory drugs. Finally, while it is not the case for everyone, some people may experience an allergic reaction to reishi mushrooms. [27] Typically the effects are very mild though, resulting in dryness of the eyes, nose, and throat, and occasional rashes breaking out on the skin.

Women who are pregnant or breastfeeding should also consult with their doctor prior to taking reishi mushrooms, as it is unclear what physiological effect this may have on young or developing children. With all of this in mind, though, the side effects are generally very mild, and it is unlikely that serious consequences will result from the addition of reishi mushrooms to a prescribed medicinal treatment.

References:

1. Singh, Manjit, Shwet Kamal, and Ved Parkash Sharma. “Status and trends in world mushroom production-III-World Production of different mushroom species in 21st century.” Mushroom Research 29.2 (2020).
2. Team, Market Intelligence. “Industry Report: Mushroom.” (2020).
3. Pagare, Saurabh, et al. “Secondary metabolites of plants and their role: Overview.” Current trends in biotechnology and pharmacy 9.3 (2015): 293-304.
4. Mau, Jeng-Leun, Hsiu-Ching Lin, and Chin-Chu Chen. “Non-volatile components of several medicinal mushrooms.” Food Research International 34.6 (2001): 521-526.
5. Zhou, Xuanwei, et al. “Ganodermataceae: natural products and their related pharmacological functions.” The American journal of Chinese medicine 35.04 (2007): 559-574.
6. Zhao Q, Jiang Y, Zhao Q, Patrick Manzi H, Su L, Liu D, Huang X, Long D, Tang Z, Zhang Y. The benefits of edible mushroom polysaccharides for health and their influence on gut microbiota: a review. Front Nutr. 2023 Jul 6;10:1213010. doi: 10.3389/fnut.2023.1213010. PMID: 37485384; PMCID: PMC10358859.
7. Venturella G, Ferraro V, Cirlincione F, Gargano ML. Medicinal Mushrooms: Bioactive Compounds, Use, and Clinical Trials. Int J Mol Sci. 2021 Jan 10;22(2):634. doi: 10.3390/ijms22020634. PMID: 33435246; PMCID: PMC7826851.
8. Zhou, Yueqin, Xiaotong Yang, and Qingyao Yang. “Recent advances on triterpenes from Ganoderma mushroom.” Food reviews international 22.3 (2006): 259-273.
9. Nishitoba, Tsuyoshi, et al. “New bitter C27 and C30 terpenoids from the fungus Ganoderma lucidum (Reishi).” Agricultural and biological chemistry 49.6 (1985): 1793-1798.
10. Deepalakshmi, K., and S. Mirunalini. “Therapeutic properties and current medical usage of medicinal mushroom: Ganoderma lucidum.” International Journal of Pharmaceutical Sciences and Research 2.8 (2011): 1922.
11. Jin, Xingzhong, et al. “Ganoderma lucidum (Reishi mushroom) for cancer treatment.” Cochrane Database of Systematic Reviews 6 (2012).
12. Zhang, Yiwen, et al. “Characterization and hepatoprotections of Ganoderma lucidum polysaccharides against multiple organ dysfunction syndrome in mice.” Oxidative Medicine and Cellular Longevity 2021 (2021).
13. Chen X, Liu M, Tang J, Wang N, Feng Y, Ma H. Research Progress on the Therapeutic Effect of Polysaccharides on Non-Alcoholic Fatty Liver Disease through the Regulation of the Gut-Liver Axis. Int J Mol Sci. 2022 Oct 3;23(19):11710. doi: 10.3390/ijms231911710. PMID: 36233011; PMCID: PMC9570256.
14. Nazaruk J, Borzym-Kluczyk M. The role of triterpenes in the management of diabetes mellitus and its complications. Phytochem Rev. 2015;14(4):675-690. doi: 10.1007/s11101-014-9369-x. Epub 2014 Jun 24. PMID: 26213526; PMCID: PMC4513225.
15. Rethy, Leah, et al. “Trends in hypertension-related cardiovascular mortality in the United States, 2000 to 2018.” Hypertension 76.3 (2020): e23-e25.
16. Kabir, Yearul, Shuichi Kimura, and Tsutomu Tamura. “Dietary effect of Ganoderma lucidum mushroom on blood pressure and lipid levels in spontaneously hypertensive rats (SHR).” Journal of nutritional science and vitaminology 34.4 (1988): 433-438.
17. Rahman, Mohammad Azizur, Noorlidah Abdullah, and Norhaniza Aminudin. “Evaluation of the antioxidative and hypo-cholesterolemic effects of lingzhi or reishi medicinal mushroom, Ganoderma lucidum (Agaricomycetes), in ameliorating cardiovascular disease.” International journal of medicinal mushrooms 20.10 (2018).
18. Garcia-Lafuentea, Ana, et al. “Mushrooms as a source of anti-inflammatory agents.” Anti-Inflammatory & Anti-Allergy Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry-Anti-Inflammatory and Anti-Allergy Agents) 9.2 (2010): 125-141.
19. Halpern, Georges M. “Medicinal mushrooms.” Progress in Nutrition 12.1 (2010): 29-36.
20. Cheng, Poh Guat, Teow Chong Teoh, and Mohammed Rizman-Idid. “Chemical compounds and computational prediction of their inhibitory effects on the HIV-1 gp120 receptor by lingzhi or reishi medicinal mushroom, Ganoderma lucidum (agaricomycetes), with antler-like morphology of fruiting bodies.” International journal of medicinal mushrooms 23.7 (2021).
21. Wanmuang, Harirak, et al. “Fatal fulminant hepatitis associated with Ganoderma lucidum (Lingzhi) mushroom powder.” Journal-Medical Association of Thailand 90.1 (2007): 179.
22. Zilberstein, Bruno, et al. “Digestive tract microbiota in healthy volunteers.” Clinics 62.1 (2007): 47-56.
23. Tang, Wenbo, et al. “A randomized, double-blind and placebo-controlled study of a Ganoderma lucidum polysaccharide extract in neurasthenia.” Journal of medicinal food 8.1 (2005): 53-58.
24. Sharma, Kuldeep, Kamal Jeet, and Ashish Baldi. “MANAGEMENT OF ACUTE MOUNTAIN SICKNESS: AN EXPLORATORY REVIEW ON HERBAL D RUGS.” Indian J. Nat. Prod 29.1 (2015): 5.
25. Gao, Yihuai, Eli Chan, and Shufeng Zhou. “Immunomodulating activities of Ganoderma, a mushroom with medicinal properties.” Food Reviews International 20.2 (2004): 123-161.
26. Geng, Ping, et al. “Antifatigue functions and mechanisms of edible and medicinal mushrooms.” BioMed research international 2017 (2017).
27. Bhardwaj, Neha, Priya Katyal, and Anil K Sharma. “Suppression of inflammatory and allergic responses by pharmacologically potent fungus Ganoderma lucidum.” Recent patents on inflammation & allergy drug discovery 8.2 (2014): 104-117.