Mushrooms have a certain mystique about them. They’re kind of funny looking and beautiful at the same time, and they can be very nutritious or extremely toxic. They are the centerpiece, or an essential component, of epicurean dishes spanning the globe – from chicken marsala in Italy, to beef bourguignon from France, to beef stroganoff from Russia, to Hungarian mushroom soup – and don’t forget the all-American portobello mushroom burger.

It is estimated that, while there are as many as 5,000,000 species of yeast and fungi in the world, only five percent have been identified. Along with bacteria and other organisms, mushrooms make up the “microbiome” of the earth’s soil.

Mushrooms’ health-promoting constituents

Although the urge is certainly to keep talking about food, this blog focuses on the medicinal qualities of mushrooms, particularly their benefit for immune support.* But there is more about food at the end.

Mushrooms have been used medicinally in traditional Chinese medicine (TCM) for thousands of years, but have only been cultivated for 800 years. The Compendium of Materia Medica, published in the 16th century, identified 1,892 medicinal ingredients, of which 20 were medicinal mushrooms.

And over the centuries since, more medicinal mushroom species have been identified – 850+ at last count in 2015. In addition to general immune support, mushrooms are widely studied for support of oncology patients, and well as for cardiovascular and liver health.*

Some important health-promoting constituents of mushrooms are:

Beta-glucans – specifically (1-3)(1-6)beta-D-glucans – are water-soluble polysaccharides found in fungal cell walls and are the primary immune-modulating constituents of medicinal mushrooms.* Because of this, mushroom supplements are often standardized to contain a certain amount of beta-glucans. Unlike alpha-glucans, which are starches found in very low amounts in mushroom fruiting bodies, water-soluble beta-glucans are found in significant amounts and are not digested by the enzymes in the GI tract. Instead they are absorbed by the cells of the small intestine, where they support mucosal immunity in the GI tract and systemic immunity.*1 Although beta-glucans primarily activate macrophages and dendritic cells, they also enhance the activity of natural killer (NK) cells, T-lymphocytes, and B-lymphocytes.*2 

Ergosterol is a molecule similar to cholesterol and is the most abundant plant sterol in mushrooms. Found in the cell walls of all mushrooms, it’s a precursor to vitamin D2.

Triterpenes possess strong antioxidant effects and support liver health.* Their adaptogenic properties help build resistance to invading organisms and to stress.*

Ergothioneine is a naturally-occurring amino acid found primarily in mushrooms. It’s a powerful antioxidant that accumulates in organs that are predisposed to high levels oxidative stress, such as the liver, kidneys, and eyes.*

Three of the most well-studied medicinal mushrooms for their immuno-supportive properties are reishi, shiitake, and maitake.

Reishi mushroom

Ganoderma lucidum (reishi mushroom) is probably one of the most well-known medicinal mushrooms in the world. This glossy, deep reddish-brown, saucer-shaped mushroom is called the “mushroom of immortality.” The benefits of reishi mushroom have been recognized in Chinese medicine for at least 2,000 years.

Known for its immune-supporting attributes, reishi mushroom is an excellent example of why many are asking, "What is reishi mushroom good for?" Reishi mushroom benefits are multi-faceted primarily due to its rich genetic profile.  Its DNA has been fully sequenced (12,910 genes),3 and more than 400 active constituents have been identified. Among the most important actives are the beta-glucan polysaccharides and triterpenes such as ganoderic acid, the latter being the likely source of its bitter taste.4 Studies show reishi supports immune function by increasing NK-cell activity and by supporting the activities of T- and B-lymphocytes and macrophages.*5 

The reishi mushroom benefits list extends beyond immune support; it is also utilized in medical spheres for its potential benefits to cardiovascular health and liver function.* And reishi mushroom health benefits also extend to sports performance – reishi has been shown to support resistance in athletes exposed to stressful situations.*6

Shiitake mushroom

Lentinus edodes (shiitake mushroom)  has been cultivated in China since 1000 AD and has important medicinal and culinary uses. Like other medicinal mushrooms benefits, a significant portion of shiitake’s health supportive qualities are provided by beta-glucans. A study analyzing the beta-glucan content of various parts of the shiitake mushroom found the highest levels in the stipe (stem), slightly less in the pileus (cap), and the least in the mycelium (roots).7

The most studied of the shiitake beta-glucans is lentinan, which has similar benefits to beta-glucans from other mushrooms – providing support for cells of the immune system, including T- and B-lymphocytes, NK-cells, and macrophages.*8 Shiitake’s polysaccharides and glycoproteins also benefit liver function and act as hepato-protectants against liver damage.* 

Maitake mushroom

Grifola frondosa (maitake mushroom) is important in both Japanese cuisine and Japanese traditional medicine (Kampo). Its Japanese name, maitake, means dancing mushroom, because it was said that those who found it would dance at their good fortune.

Maitake enhances NK-cell activity, macrophages, and cytotoxic T-cells.* In addition to its immuno-supportive benefits, maitake is hepato-protective against acetaminophen toxicity.* It also helps maintain healthy blood sugar levels,9 possibly due to the high molecular weight glycoprotein in its extract.*

In a study of the immuno-supportive benefits of maitake, shiitake, or both, the combination was significantly more effective than either species alone.*10

Nutritional value of mushrooms

Mushrooms provide many nutritional benefits: They are good sources of fiber and vegan protein and are very low in sodium and fat. 

One study of eight edible mushrooms, including shiitake, found fiber content ranged from 25-46 percent, with shiitake being among the top three. Protein ranged from 16-37 percent, and all mushrooms tested contained a full complement of essential amino acids.11 

Mushrooms also contain various vitamins and minerals, including B vitamins, vitamin D2, potassium, selenium, zinc, and copper. Mushrooms made the Environmental Working Group’s 2023 list of “Top 15 Cleanest” – meaning they are among the 15 items of produce with the lowest amount of pesticide residues.12

What is the best way to eat these “medicinal” mushrooms?

Shiitake mushrooms are best prepared by sautéing them lightly in butter or olive oil until tender. They can then be mixed with eggs or pasta or used as a pizza topping. You can also add them to miso soup along with sea vegetables like kelp. Or try this yummy-sounding mushroom risotto recipe.

The delicate nature of maitake mushrooms appeals to many individuals who don’t like the rubbery texture of other varieties of mushrooms. Because of their large size, they need to be gently pulled apart into smaller pieces before cooking (if you sauté them) and used in a way similar to the shiitake mushroom. However, if you want to grill them, then you can keep them whole. This FoodChannel.com recipe gives the details of pressing them into steaks, marinating them, and then grilling them. 

Reishi mushrooms are probably the most difficult to cook with. Because of their tough, bitter nature, they are usually prepared for medicinal purposes as opposed to a culinary delight. Although the young outer portions can be eaten fresh, they can sometimes cause stomach upset or skin rashes, so care should be taken to dry them prior to consumption. Because of their bitterness, they are often mixed with something else bitter, like chocolate or coffee.

Find more support for foundational nutrition with Thorne’s Daily Greens Plus, a comprehensive greens powder with 28 powerhouse ingredients – including reishi, shiitake, and maitake extracts, plus lion’s mane and chaga – to provide antioxidant support, enhanced endurance, and healthy aging properties.*

Needing to jumpstart your daily workout? Then try Thorne’s Pre-Workout Elite, a citrus berry-flavored powder featuring a PeakO2® Mushroom Blend of six adaptogenic mushrooms, including reishi and shiitake. Pre-Workout Elite is NSF Certifed for Sport® and supports optimal focus, strength, and output with naturally derived ingredients.*

References

  1. Batbayar S, Lee D, Kim H. Immunomodulation of fungal β-glucan in host defense signaling by dectin-1. Biomol Ther (Seoul). 2012;20(5):433-445. 
  2. Kim H, Hong J, Kim Y, Han S. Stimulatory effect of β-glucans on immune cells. Immune Netw 2011;11(4):191-195. 
  3. Binder M, Justo A, Riley R, et al. Phylogenetic and phylogenomic overview of the Polyporales. Mycologia 2013;105(6):1350-1373. 
  4. Wachtel-Galor S, Yuen J, Buswell J, et al. Ganoderma lucidum (lingzhi or reishi): A medicinal mushroom. In: Benzie I, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2011.
  5. Xu Z, Chen X, Zhong Z, et al. Ganoderma lucidum polysaccharides: immunomodulation and potential anti-tumor activities. Am J Chin Med 2011;39(1):15-27.
  6. Zhang Y, Lin Z, Hu Y, Wang F. Effect of Ganoderma lucidum capsules on T lymphocyte subsets in football players on "living high-training low." Br J Sports Med 2008;42(10):819-822. 
  7. Bak W, Park J, Park Y, Ka K. Determination of glucan contents in the fruiting bodies and mycelia of Lentinula edodes cultivars. Mycobiology 2014;42(3):301-304. 
  8. Wasser S. Shiitake (Lentinus edodes); In: Coates P, Blackman M, Cragg G, et al, editors. Encyclopedia of Dietary Supplements. Boca Raton, FL: CRC Press; 2004.
  9. Guo W, Deng J, Pan Y, et al. Hypoglycemic and hypolipidemic activities of Grifola frondosa polysaccharides and their relationships with the modulation of intestinal microflora in diabetic mice induced by high-fat diet and streptozotocin. Int J Biol Macromol 2020;153:1231-1240.
  10. Vetvicka V, Vetvickova J. Immune-enhancing effects of maitake (Grifola frondosa) and shiitake (Lentinula edodes) extracts. Ann Transl Med 2014;2(2):14. doi:10.3978/j.issn.2305-5839.2014.01.05
  11. Bach F, Helm C, Bellettini M, et al. Edible mushrooms: a potential source of essential amino acids, glucans, and minerals. Int J Food Sci Technol 2017;52(11):2382-2392. 
  12. EWG’s 2020 Shopper’s Guide to Pesticides in Produce. https://www.ewg.org/foodnews/summary.php [accessed July 30, 2020]